Functions and Integer Triple Pointer ================================================= In this section, you are going to learn .. panels:: :container: container pb-4 :column: col-lg-12 p-2 :card: shadow What are the calling conventions of integer triple pointer ? .. panels:: :container: container pb-4 :column: col-lg-12 p-2 :card: shadow Call by Value .. panels:: :container: container pb-4 :column: col-lg-12 p-2 :card: shadow Call by Reference .. panels:: :container: container pb-4 :column: col-lg-12 p-2 :card: shadow Revisit Basics : :doc:`../../basic_ptr/basic_int_ptr/int_tp` .. panels:: :container: container pb-4 :column: col-lg-12 p-2 :card: shadow Topics in this section, * :ref:`Integer Triple Pointer : Syntax ` * :ref:`Integer Triple Pointer : FAQs ` * :ref:`Integer Triple Pointer : fun(expression) ` * :ref:`Rules for Call By Value ` * :ref:`Example : Call by Value : Pass Integer : tp[1][1][1] ` * :ref:`Example : Call by Value : Pass Integer : ***tp ` * :ref:`Rules for Call By Reference ` * :ref:`Example : Call by Reference : &tp[1][1] ` * :ref:`Example : Call by Reference : tp[1] ` * :ref:`Examples of Call by Value ` * :ref:`Example 1 : Call by Value : Pass Integer : tp[0][0][0], tp[1][0][0], tp[2][0][0] ` * :ref:`Example 2 : Call by Value : Pass Integer : \*\*\*tp, \*(\*(\*(tp + 1) + 0) + 0), \*(\*(\*(tp + 2) + 0) + 0) ` * :ref:`Examples of Call by Reference ` * :ref:`Example 3 : Call by Reference : Pass Single dimension arrays which are part of a triple pointer to a function ` * :ref:`Example 4 : Call by Reference : Pass Address of Single dimension arrays which are part of a triple pointer to a function ` * :ref:`Example 5 : Call by Reference : Pass Double dimension arrays which are part of a Triple dimension array to a function ` * :ref:`Example 6 : Call by Reference : Pass Address of Double dimension arrays which are part of a Triple dimension array to a function ` * :ref:`Example 7 : Call by Reference : Pass Address of Triple Dimension array to a function ` .. _funcs_n_ptrs_int_tp_ex_0: .. tab-set:: .. tab-item:: Integer Triple Pointer : Syntax .. panels:: :container: container pb-4 :column: col-lg-12 p-2 :card: shadow int \*\*\*tp; .. _funcs_n_ptrs_int_tp_ex_0_1: .. tab-set:: .. tab-item:: Integer Triple Pointer : FAQs Consider a integer triple pointer .. code-block:: c int ***tp; .. panels:: :container: container pb-4 :column: col-lg-12 p-2 :card: shadow Let us answer few basic questions about integer triple pointer .. _funcs_n_ptrs_int_tp_ex_6: .. tab-set:: .. tab-item:: Integer Triple Pointer : fun(expression) .. panels:: :container: container pb-4 :column: col-lg-12 p-2 :card: shadow If ``fun(x)`` is the function call, then ``fun(typeof(x))`` is the prototype / definition ========================== ================================ ========================================================================== Function Call Function Definition Observations ========================== ================================ ========================================================================== fun(tp[0][0][0]) void fun(int x) {} * Call by Value fun(tp[1][0][0]) void fun(int x) {} * Call by Value fun(tp[2][0][0]) void fun(int x) {} * Call by Value fun(&tp[0][0][0]) void fun(int \*p) {} * Call by Reference fun(&tp[1][0][0]) void fun(int \*p) {} * Call by Reference fun(&tp[2][0][0]) void fun(int \*p) {} * Call by Reference fun(tp[0][0]) void fun(int \*p) {} * Call by Reference fun(tp[1][0]) void fun(int \*p) {} * Call by Reference fun(tp[2][0]) void fun(int \*p) {} * Call by Reference fun(&tp[0][0]) void fun(int \*\*p) {} * Call by Reference fun(&tp[1][0]) void fun(int \*\*p) {} * Call by Reference fun(&tp[2][0]) void fun(int \*\*p) {} * Call by Reference fun(\*\*tp) void fun(int \*p) {} * Call by Reference fun(\*(\*(tp + 1) + 0)) void fun(int \*p) {} * Call by Reference fun(\*(\*(tp + 2) + 0)) void fun(int \*p) {} * Call by Reference fun(tp[0]) void fun(int \*\*p) {} * Call by Reference fun(tp[1]) void fun(int \*\*p) {} * Call by Reference fun(tp[2]) void fun(int \*\*p) {} * Call by Reference fun(&tp[0]) void fun(int \*\*\*p) {} * Call by Reference fun(\*tp) void fun(int \*\*p) {} * Call by Reference fun(\*(tp + 1)) void fun(int \*\*p) {} * Call by Reference fun(\*(tp + 2)) void fun(int \*\*p) {} * Call by Reference fun(tp) void fun(int \*\*\*p) {} * Call by Reference fun(&tp) void fun(int \*\*\*\*p) {} * Call by Reference ========================== ================================ ========================================================================== .. panels:: :container: container pb-4 :column: col-lg-12 p-2 :card: shadow Let us understand the reason behind above prototypes ! .. _funcs_n_ptrs_int_tp_ex_8: .. tab-set:: .. tab-item:: Rules for Call By Value .. panels:: :container: container pb-4 :column: col-lg-12 p-2 :card: shadow If Declaration has THREE dereference operators, and * Expression has THREE dereference operators \* \* \*, and * Expression does not have ``&`` * then it is call by value .. panels:: :container: container pb-4 :column: col-lg-12 p-2 :card: shadow If Declaration has THREE dereference operators, and * Expression has THREE dereference operators \* \* [ ], and * Expression does not have ``&`` * then it is call by value .. panels:: :container: container pb-4 :column: col-lg-12 p-2 :card: shadow If Declaration has THREE dereference operators, and * Expression has THREE dereference operators \* [ ] [ ], and * Expression does not have ``&`` * then it is call by value .. panels:: :container: container pb-4 :column: col-lg-12 p-2 :card: shadow If Declaration has THREE dereference operators, and * Expression has THREE dereference operators [] [] [], and * Expression does not have ``&`` * then it is call by value .. panels:: :container: container pb-4 :column: col-lg-12 p-2 :card: shadow Let us look at examples .. _funcs_n_ptrs_int_tp_ex_9: .. tab-set:: .. tab-item:: Example 1 : Call by Value : Pass Integer : tp[1][1][1] * Step 1 : Consider a triple dimension array created using a integer triple pointer .. code-block:: c // Define a triple integer pointer int ***tp; // Allocate memory to create array[2][3][4] tp = malloc(2 * sizeof(int **) ); for (int i = 0; i < 2; i++) { tp[i] = malloc(3 * sizeof(int *) ); for (int j = 0; j < 3; j++) { tp[i][j] = malloc(4 * sizeof(int)); } } // Assign data int data = 99; for (int i = 0; i < 2; i++) { for (int j = 0; j < 3; j++) { for (int k = 0; k < 4; k++) { tp[i][j][k] = data++; } } } .. panels:: :container: container pb-4 :column: col-lg-12 p-2 :card: shadow Condition 1 : Declaration has THREE dereference operators [ ], [ ] and [ ] * Step 2 : Consider an expression ``tp[1][1][1]`` .. panels:: :container: container pb-4 :column: col-lg-12 p-2 :card: shadow Condition 2 : Expression has THREE dereference operators [ ], [ ] and [ ] .. panels:: :container: container pb-4 :column: col-lg-12 p-2 :card: shadow Note : ``[ ]`` and ``*`` are dereference operators .. panels:: :container: container pb-4 :column: col-lg-12 p-2 :card: shadow Condition 3 : Expression DOES NOT have ``&`` operator .. panels:: :container: container pb-4 :column: col-lg-12 p-2 :card: shadow Hence ``tp[1][1][1]`` is Call By Value .. _funcs_n_ptrs_int_tp_ex_10: .. tab-set:: .. tab-item:: Example 2 : Call by Value : Pass Integer : \*\*\*tp * Step 1 : Consider a triple dimension array created using a integer triple pointer .. code-block:: c // Define a triple integer pointer int ***tp; // Allocate memory to create array[2][3][4] tp = malloc(2 * sizeof(int **) ); for (int i = 0; i < 2; i++) { tp[i] = malloc(3 * sizeof(int *) ); for (int j = 0; j < 3; j++) { tp[i][j] = malloc(4 * sizeof(int)); } } // Assign data int data = 99; for (int i = 0; i < 2; i++) { for (int j = 0; j < 3; j++) { for (int k = 0; k < 4; k++) { tp[i][j][k] = data++; } } } .. panels:: :container: container pb-4 :column: col-lg-12 p-2 :card: shadow Condition 1 : Declaration has THREE dereference operators [ ], [ ] and [ ] * Step 2 : Consider an expression ``***tp`` .. panels:: :container: container pb-4 :column: col-lg-12 p-2 :card: shadow Condition 2 : Expression has THREE dereference operators \*, \* and \* .. panels:: :container: container pb-4 :column: col-lg-12 p-2 :card: shadow Note : ``[ ]`` and ``*`` are dereference operators .. panels:: :container: container pb-4 :column: col-lg-12 p-2 :card: shadow Condition 3 : Expression DOES NOT have ``&`` operator .. panels:: :container: container pb-4 :column: col-lg-12 p-2 :card: shadow Hence ``***tp`` is Call By Value .. _funcs_n_ptrs_int_tp_ex_11: .. tab-set:: .. tab-item:: Rules for Call By Reference .. panels:: :container: container pb-4 :column: col-lg-12 p-2 :card: shadow If Declaration has THREE dereference operators, and * Expression has THREE dereference operators \* \* \* OR \* \* [] OR \* [] [] OR [] [] [] and * Expression has & * then it is call by reference * Example : &tp[0][0][0], &tp[1][2][3] .. panels:: :container: container pb-4 :column: col-lg-12 p-2 :card: shadow If Declaration has THREE dereference operators, and * Expression has TWO dereference operator \* \* OR [] [] OR \* [] * then it is call by reference * Example : tp[0][0] .. panels:: :container: container pb-4 :column: col-lg-12 p-2 :card: shadow If Declaration has THREE dereference operators, and * Expression has ONE dereference operators, \* OR [ ] * then it is call by reference * Example : tp[0] .. panels:: :container: container pb-4 :column: col-lg-12 p-2 :card: shadow If Declaration has THREE dereference operators, and * Expression has ZERO dereference operators * then it is call by reference * Example : tp .. _funcs_n_ptrs_int_tp_ex_12: .. tab-set:: .. tab-item:: Example 1 : Call by Reference : &tp[1][1][1] * Step 1 : Consider a triple dimension array created using a integer triple pointer .. code-block:: c // Define a triple integer pointer int ***tp; // Allocate memory to create array[2][3][4] tp = malloc(2 * sizeof(int **) ); for (int i = 0; i < 2; i++) { tp[i] = malloc(3 * sizeof(int *) ); for (int j = 0; j < 3; j++) { tp[i][j] = malloc(4 * sizeof(int)); } } // Assign data int data = 99; for (int i = 0; i < 2; i++) { for (int j = 0; j < 3; j++) { for (int k = 0; k < 4; k++) { tp[i][j][k] = data++; } } } .. panels:: :container: container pb-4 :column: col-lg-12 p-2 :card: shadow Condition 1 : Declaration has THREE dereference operators [ ] [ ] and [ ] * Step 2 : Consider an expression ``&tp[1][1][1]`` .. panels:: :container: container pb-4 :column: col-lg-12 p-2 :card: shadow Condition 2 : Expression has THREE dereference operators [ ] [ ] and [ ] .. panels:: :container: container pb-4 :column: col-lg-12 p-2 :card: shadow Note : ``[ ]`` and ``*`` are dereference operators .. panels:: :container: container pb-4 :column: col-lg-12 p-2 :card: shadow Condition 3 : Expression has ``&`` operator .. panels:: :container: container pb-4 :column: col-lg-12 p-2 :card: shadow Hence ``&tp[1][1][1]`` is Call By Reference .. _funcs_n_ptrs_int_tp_ex_13: .. tab-set:: .. tab-item:: Example 2 : Call by Reference : tp[1] * Step 1 : Consider a triple dimension array created using a integer triple pointer .. code-block:: c // Define a triple integer pointer int ***tp; // Allocate memory to create array[2][3][4] tp = malloc(2 * sizeof(int **) ); for (int i = 0; i < 2; i++) { tp[i] = malloc(3 * sizeof(int *) ); for (int j = 0; j < 3; j++) { tp[i][j] = malloc(4 * sizeof(int)); } } // Assign data int data = 99; for (int i = 0; i < 2; i++) { for (int j = 0; j < 3; j++) { for (int k = 0; k < 4; k++) { tp[i][j][k] = data++; } } } .. panels:: :container: container pb-4 :column: col-lg-12 p-2 :card: shadow Condition 1 : Declaration has THREE dereference operators [ ] [ ] and [ ] * Step 2 : Consider an expression ``tp[1]`` .. panels:: :container: container pb-4 :column: col-lg-12 p-2 :card: shadow Condition 2 : Expression has ONE dereference operator .. panels:: :container: container pb-4 :column: col-lg-12 p-2 :card: shadow Note : ``[ ]`` and ``*`` are dereference operators .. panels:: :container: container pb-4 :column: col-lg-12 p-2 :card: shadow Condition 3 : Expression DOES NOT have ``&`` operator .. panels:: :container: container pb-4 :column: col-lg-12 p-2 :card: shadow Hence ``tp[1]`` is Call By Reference .. _funcs_n_ptrs_int_tp_examples_call_by_value: .. tab-set:: .. tab-item:: Examples of Call by Value .. panels:: :container: container pb-4 :column: col-lg-12 p-2 :card: shadow Let us look at examples of Call by Value .. _funcs_n_ptrs_int_tp_ex_15: .. tab-set:: .. tab-item:: Example 1 : Call by Value : Pass Integer : tp[0][0][0], tp[1][0][0] * Step 1 : Consider a triple dimension array created using a integer triple pointer .. code-block:: c // Define a triple integer pointer int ***tp; // Allocate memory to create array[2][3][4] tp = malloc(2 * sizeof(int **) ); for (int i = 0; i < 2; i++) { tp[i] = malloc(3 * sizeof(int *) ); for (int j = 0; j < 3; j++) { tp[i][j] = malloc(4 * sizeof(int)); } } // Assign data int data = 99; for (int i = 0; i < 2; i++) { for (int j = 0; j < 3; j++) { for (int k = 0; k < 4; k++) { tp[i][j][k] = data++; } } } * Step 2 : Pass tp[0][0][0], tp[1][0][0] to a function ``fun`` .. code-block:: c fun(tp[0][0][0]); fun(tp[1][0][0]); * Step 3 : Define function ``fun`` .. code-block:: c void fun(int c) { c = 999; } * Step 4 : Note that it is call by Value for below reason .. panels:: :container: container pb-4 :column: col-lg-12 p-2 :card: shadow Condition 1 : Declaration has THREE dereference operators [ ] [ ] and [ ] .. panels:: :container: container pb-4 :column: col-lg-12 p-2 :card: shadow Condition 2 : Expression has THREE dereference operators [ ] [ ] and [ ] .. panels:: :container: container pb-4 :column: col-lg-12 p-2 :card: shadow Condition 3 : Expression DOES NOT have ``&`` operator .. panels:: :container: container pb-4 :column: col-lg-12 p-2 :card: shadow Means changing value of integer inside function DOES NOT affect value of integer in Caller ! * Step 5 : Free memory after use .. code-block:: c for (int i = 0; i < 2; i++) { for (int j = 0; j < 3; j++) { free( tp[i][j] ); } free( tp[i] ); } free(tp); * See full program below .. code-block:: c #include #include void fun(int c) { c = 999; } int main(void) { // Define a triple integer pointer int ***tp; // Allocate memory to create array[2][3][4] tp = malloc(2 * sizeof(int **) ); for (int i = 0; i < 2; i++) { tp[i] = malloc(3 * sizeof(int *) ); for (int j = 0; j < 3; j++) { tp[i][j] = malloc(4 * sizeof(int)); } } // Assign data int data = 99; for (int i = 0; i < 2; i++) { for (int j = 0; j < 3; j++) { for (int k = 0; k < 4; k++) { tp[i][j][k] = data++; } } } printf("----- Before Call By Value -----\n"); printf("tp[0][0][0] = %d\n", tp[0][0][0]); printf("tp[1][0][0] = %d\n", tp[1][0][0]); fun(tp[0][0][0]); fun(tp[1][0][0]); printf("----- After Call By Value -----\n"); printf("tp[0][0][0] = %d\n", tp[0][0][0]); printf("tp[1][0][0] = %d\n", tp[1][0][0]); for (int i = 0; i < 2; i++) { for (int j = 0; j < 3; j++) { free( tp[i][j] ); } free( tp[i] ); } free(tp); return 0; } * Output is as below .. code-block:: c ----- Before Call By Value ----- tp[0][0][0] = 99 tp[1][0][0] = 111 ----- After Call By Value ----- tp[0][0][0] = 99 tp[1][0][0] = 111 .. _funcs_n_ptrs_int_tp_ex_16: .. tab-set:: .. tab-item:: Example 2 : Call by Value : Pass Integer : \*\*\*tp, \*(\*(\*(tp + 1) + 0) + 0) * Step 1 : Consider a triple dimension array created using a integer triple pointer .. code-block:: c // Define a triple integer pointer int ***tp; // Allocate memory to create array[2][3][4] tp = malloc(2 * sizeof(int **) ); for (int i = 0; i < 2; i++) { tp[i] = malloc(3 * sizeof(int *) ); for (int j = 0; j < 3; j++) { tp[i][j] = malloc(4 * sizeof(int)); } } // Assign data int data = 99; for (int i = 0; i < 2; i++) { for (int j = 0; j < 3; j++) { for (int k = 0; k < 4; k++) { tp[i][j][k] = data++; } } } * Step 2 : Pass \*\*\*tp, \*(\*(\*(tp + 1) + 0) + 0) to a function ``fun`` .. code-block:: c fun( ***tp ); fun( *(*(*(tp + 1) + 0) + 0) ); * Step 3 : Define function ``fun`` .. code-block:: c void fun(int c) { c = 999; } * Step 4 : Note that it is call by Value for below reason .. panels:: :container: container pb-4 :column: col-lg-12 p-2 :card: shadow Condition 1 : Declaration has THREE dereference operators [ ] [ ] and [ ] .. panels:: :container: container pb-4 :column: col-lg-12 p-2 :card: shadow Condition 2 : Expression has THREE dereference operators \* \* and \* .. panels:: :container: container pb-4 :column: col-lg-12 p-2 :card: shadow Condition 3 : Expression DOES NOT have ``&`` operator .. panels:: :container: container pb-4 :column: col-lg-12 p-2 :card: shadow Means changing value of integer inside function DOES NOT affect value of integer in Caller ! * Step 5 : Free memory after use .. code-block:: c for (int i = 0; i < 2; i++) { for (int j = 0; j < 3; j++) { free( tp[i][j] ); } free( tp[i] ); } free(tp); * See full program below .. code-block:: c #include #include void fun(int c) { c = 999; } int main(void) { // Define a triple integer pointer int ***tp; // Allocate memory to create array[2][3][4] tp = malloc(2 * sizeof(int **) ); for (int i = 0; i < 2; i++) { tp[i] = malloc(3 * sizeof(int *) ); for (int j = 0; j < 3; j++) { tp[i][j] = malloc(4 * sizeof(int)); } } // Assign data int data = 99; for (int i = 0; i < 2; i++) { for (int j = 0; j < 3; j++) { for (int k = 0; k < 4; k++) { tp[i][j][k] = data++; } } } printf("----- Before Call By Value -----\n"); printf(" ***tp = %d\n", ***tp ); printf(" *(*(*(tp + 1) + 0) + 0) = %d\n", *(*(*(tp + 1) + 0) + 0) ); fun( ***tp ); fun( *(*(*(tp + 1) + 0) + 0) ); printf("----- After Call By Value -----\n"); printf(" ***tp = %d\n", ***tp ); printf(" *(*(*(tp + 1) + 0) + 0) = %d\n", *(*(*(tp + 1) + 0) + 0) ); for (int i = 0; i < 2; i++) { for (int j = 0; j < 3; j++) { free( tp[i][j] ); } free( tp[i] ); } free(tp); return 0; } * Output is as below .. code-block:: c ----- Before Call By Value ----- ***tp = 99 *(*(*(tp + 1) + 0) + 0) = 111 ----- After Call By Value ----- ***tp = 99 *(*(*(tp + 1) + 0) + 0) = 111 .. _funcs_n_ptrs_int_tp_examples_call_by_reference: .. tab-set:: .. tab-item:: Examples of Call by Value .. panels:: :container: container pb-4 :column: col-lg-12 p-2 :card: shadow Let us look at examples of Call by Reference .. _funcs_n_ptrs_int_tp_ex_17: .. tab-set:: .. tab-item:: Example 3 : Call by Reference : Pass Single dimension arrays which are part of a triple pointer to a function * Step 1 : Consider a triple dimension array created using a integer triple pointer .. code-block:: c // Define a triple integer pointer int ***tp; // Allocate memory to create array[2][3][4] tp = malloc(2 * sizeof(int **) ); for (int i = 0; i < 2; i++) { tp[i] = malloc(3 * sizeof(int *) ); for (int j = 0; j < 3; j++) { tp[i][j] = malloc(4 * sizeof(int)); } } // Assign data int data = 99; for (int i = 0; i < 2; i++) { for (int j = 0; j < 3; j++) { for (int k = 0; k < 4; k++) { tp[i][j][k] = data++; } } } .. panels:: :container: container pb-4 :column: col-lg-12 p-2 :card: shadow There are 6 single dimension arrays in ``int \*\*\*tp`` with respect to above allocation tp[0][0] tp[0][1] tp[0][2] tp[1][0] tp[1][1] tp[1][2] * Step 2.1 : Method 1 : Pass tp[0][0], tp[1][0] to a function ``fun`` .. code-block:: c fun( tp[0][0] ); fun( tp[1][0] ); * Step 2.2 : Method 2 : Pass &tp[0][0][0], &tp[1][0][0] to a function ``fun`` .. code-block:: c fun( &tp[0][0][0] ); fun( &tp[1][0][0] ); * Step 2.3 : Method 3 : Pass \*\*tp, \*(\*(tp + 1) + 0) to a function ``fun`` .. code-block:: c fun( **tp ); fun( *(*(tp + 1) + 0) ); * Step 3.1 : Define function ``fun`` .. code-block:: c void fun(int *ptr) { } * Step 4 : Note that it is call by Reference. Means contents of single dimension array can be changed inside function ``fun`` .. code-block:: c void fun(int *ptr) { } * Step 5 : Free memory after use .. code-block:: c for (int i = 0; i < 2; i++) { for (int j = 0; j < 3; j++) { free( tp[i][j] ); } free( tp[i] ); } free(tp); * See full program below .. code-block:: c #include #include void fun(int *ptr) { ptr[0] = 666; ptr[1] = 777; ptr[2] = 888; ptr[3] = 999; } int main(void) { // Define a triple integer pointer int ***tp; // Allocate memory to create array[2][3][4] tp = malloc(2 * sizeof(int **) ); for (int i = 0; i < 2; i++) { tp[i] = malloc(3 * sizeof(int *) ); for (int j = 0; j < 3; j++) { tp[i][j] = malloc(4 * sizeof(int)); } } // Assign data int data = 99; for (int i = 0; i < 2; i++) { for (int j = 0; j < 3; j++) { for (int k = 0; k < 4; k++) { tp[i][j][k] = data++; } } } printf("----- Before Call By Reference -----\n"); for (int i = 0; i < 2; i++) { for (int j = 0; j < 3; j++) { for (int k = 0; k < 4; k++) { printf("tp[%d][%d][%d] = %d ", i, j, k, tp[i][j][k]); } printf("\n"); } printf("\n"); } // Method 1 : Access Single dimension arrays fun( tp[0][0] ); fun( tp[1][0] ); // Method 2 : Access Single dimension arrays fun( &tp[0][0][0] ); fun( &tp[1][0][0] ); // Method 3 : Access Single dimension arrays fun( **tp ); fun( *(*(tp + 1) + 0) ); printf("----- After Call By Reference -----\n"); for (int i = 0; i < 2; i++) { for (int j = 0; j < 3; j++) { for (int k = 0; k < 4; k++) { printf("tp[%d][%d][%d] = %d ", i, j, k, tp[i][j][k]); } printf("\n"); } printf("\n"); } for (int i = 0; i < 2; i++) { for (int j = 0; j < 3; j++) { free( tp[i][j] ); } free( tp[i] ); } free(tp); return 0; } * Output is as below .. code-block:: c ----- Before Call By Reference ----- tp[0][0][0] = 99 tp[0][0][1] = 100 tp[0][0][2] = 101 tp[0][0][3] = 102 tp[0][1][0] = 103 tp[0][1][1] = 104 tp[0][1][2] = 105 tp[0][1][3] = 106 tp[0][2][0] = 107 tp[0][2][1] = 108 tp[0][2][2] = 109 tp[0][2][3] = 110 tp[1][0][0] = 111 tp[1][0][1] = 112 tp[1][0][2] = 113 tp[1][0][3] = 114 tp[1][1][0] = 115 tp[1][1][1] = 116 tp[1][1][2] = 117 tp[1][1][3] = 118 tp[1][2][0] = 119 tp[1][2][1] = 120 tp[1][2][2] = 121 tp[1][2][3] = 122 ----- After Call By Reference ----- tp[0][0][0] = 666 tp[0][0][1] = 777 tp[0][0][2] = 888 tp[0][0][3] = 999 tp[0][1][0] = 103 tp[0][1][1] = 104 tp[0][1][2] = 105 tp[0][1][3] = 106 tp[0][2][0] = 107 tp[0][2][1] = 108 tp[0][2][2] = 109 tp[0][2][3] = 110 tp[1][0][0] = 666 tp[1][0][1] = 777 tp[1][0][2] = 888 tp[1][0][3] = 999 tp[1][1][0] = 115 tp[1][1][1] = 116 tp[1][1][2] = 117 tp[1][1][3] = 118 tp[1][2][0] = 119 tp[1][2][1] = 120 tp[1][2][2] = 121 tp[1][2][3] = 122 .. _funcs_n_ptrs_int_tp_ex_18: .. tab-set:: .. tab-item:: Example 4 : Call by Reference : Pass Address of Single dimension arrays which are part of a triple pointer to a function * Step 1 : Consider a triple dimension array created using a integer triple pointer .. code-block:: c // Define a triple integer pointer int ***tp; // Allocate memory to create array[2][3][4] tp = malloc(2 * sizeof(int **) ); for (int i = 0; i < 2; i++) { tp[i] = malloc(3 * sizeof(int *) ); for (int j = 0; j < 3; j++) { tp[i][j] = malloc(4 * sizeof(int)); } } // Assign data int data = 99; for (int i = 0; i < 2; i++) { for (int j = 0; j < 3; j++) { for (int k = 0; k < 4; k++) { tp[i][j][k] = data++; } } } .. panels:: :container: container pb-4 :column: col-lg-12 p-2 :card: shadow There are 6 single dimension arrays in tp[0][0] tp[0][1] tp[0][2] tp[1][0] tp[1][1] tp[1][2] .. panels:: :container: container pb-4 :column: col-lg-12 p-2 :card: shadow Address of single dimension arrays is simply &tp[0][0] &tp[0][1] &tp[0][2] &tp[1][0] &tp[1][1] &tp[1][2] * Step 2.1 : Method 1 : Pass address of single dimension arrays to a function ``fun`` .. code-block:: c fun( &tp[0][0] ); fun( &tp[1][0] ); * Step 2.2 : Method 2 : Pass address of single dimension arrays to a function ``fun`` .. code-block:: c fun( tp[0] ); fun( tp[1] ); * Step 2.3 : Method 2 : Pass address of single dimension arrays to a function ``fun`` .. code-block:: c fun( *tp ); fun( *(tp + 1) ); * Step 3.1 : Define the function ``fun`` .. code-block:: c void fun(int **ptr ) { } * Step 3.3 : Define the function ``fun`` to change the contents of single dimension array integer by integer .. code-block:: c void fun(int **ptr) { (*ptr)[0] = 666; (*ptr)[1] = 777; (*ptr)[2] = 888; (*ptr)[3] = 999; } * Step 4 : Free memory after use .. code-block:: c for (int i = 0; i < 2; i++) { for (int j = 0; j < 3; j++) { free( tp[i][j] ); } free( tp[i] ); } free(tp); * See full program below .. code-block:: c #include #include void fun(int **ptr ) { (*ptr)[0] = 666; (*ptr)[1] = 777; (*ptr)[2] = 888; (*ptr)[3] = 999; } int main(void) { // Define a triple integer pointer int ***tp; // Allocate memory to create array[2][3][4] tp = malloc(2 * sizeof(int **) ); for (int i = 0; i < 2; i++) { tp[i] = malloc(3 * sizeof(int *) ); for (int j = 0; j < 3; j++) { tp[i][j] = malloc(4 * sizeof(int)); } } // Assign data int data = 99; for (int i = 0; i < 2; i++) { for (int j = 0; j < 3; j++) { for (int k = 0; k < 4; k++) { tp[i][j][k] = data++; } } } printf("----- Before Call By Reference -----\n"); for (int i = 0; i < 2; i++) { for (int j = 0; j < 3; j++) { for (int k = 0; k < 4; k++) { printf("tp[%d][%d][%d] = %d ", i, j, k, tp[i][j][k]); } printf("\n"); } printf("\n"); } // Method 1 : Access Single dimension arrays fun( &tp[0][0] ); fun( &tp[1][0] ); // Method 2 : Access Single dimension arrays fun( tp[0] ); fun( tp[1] ); // Method 3 : Access Single dimension arrays fun( *tp ); fun( *(tp + 1) ); printf("----- After Call By Reference -----\n"); for (int i = 0; i < 2; i++) { for (int j = 0; j < 3; j++) { for (int k = 0; k < 4; k++) { printf("tp[%d][%d][%d] = %d ", i, j, k, tp[i][j][k]); } printf("\n"); } printf("\n"); } for (int i = 0; i < 2; i++) { for (int j = 0; j < 3; j++) { free( tp[i][j] ); } free( tp[i] ); } free(tp); return 0; } * Output is as below .. code-block:: c ----- Before Call By Reference ----- tp[0][0][0] = 99 tp[0][0][1] = 100 tp[0][0][2] = 101 tp[0][0][3] = 102 tp[0][1][0] = 103 tp[0][1][1] = 104 tp[0][1][2] = 105 tp[0][1][3] = 106 tp[0][2][0] = 107 tp[0][2][1] = 108 tp[0][2][2] = 109 tp[0][2][3] = 110 tp[1][0][0] = 111 tp[1][0][1] = 112 tp[1][0][2] = 113 tp[1][0][3] = 114 tp[1][1][0] = 115 tp[1][1][1] = 116 tp[1][1][2] = 117 tp[1][1][3] = 118 tp[1][2][0] = 119 tp[1][2][1] = 120 tp[1][2][2] = 121 tp[1][2][3] = 122 ----- After Call By Reference ----- tp[0][0][0] = 666 tp[0][0][1] = 777 tp[0][0][2] = 888 tp[0][0][3] = 999 tp[0][1][0] = 103 tp[0][1][1] = 104 tp[0][1][2] = 105 tp[0][1][3] = 106 tp[0][2][0] = 107 tp[0][2][1] = 108 tp[0][2][2] = 109 tp[0][2][3] = 110 tp[1][0][0] = 666 tp[1][0][1] = 777 tp[1][0][2] = 888 tp[1][0][3] = 999 tp[1][1][0] = 115 tp[1][1][1] = 116 tp[1][1][2] = 117 tp[1][1][3] = 118 tp[1][2][0] = 119 tp[1][2][1] = 120 tp[1][2][2] = 121 tp[1][2][3] = 122 .. _funcs_n_ptrs_int_tp_ex_19: .. tab-set:: .. tab-item:: Example 5 : Call by Reference : Pass Double dimension arrays which are part of a Triple dimension array to a function * Step 1 : Consider a triple dimension array created using a integer triple pointer .. code-block:: c // Define a triple integer pointer int ***tp; // Allocate memory to create array[2][3][4] tp = malloc(2 * sizeof(int **) ); for (int i = 0; i < 2; i++) { tp[i] = malloc(3 * sizeof(int *) ); for (int j = 0; j < 3; j++) { tp[i][j] = malloc(4 * sizeof(int)); } } // Assign data int data = 99; for (int i = 0; i < 2; i++) { for (int j = 0; j < 3; j++) { for (int k = 0; k < 4; k++) { tp[i][j][k] = data++; } } } * Step 2 : Pass Double dimension array to function ``fun`` .. code-block:: c fun(tp[1]); * Step 3.1 : Define function ``fun`` .. code-block:: c void fun(int **ptr) { // Access Integers and Change for(int i = 0; i < 3; i++) { for(int j = 0; j < 4; j++) { ptr[i][j] = 999; } } } * Step 3.2 : Access and Change integers inside function ``fun`` .. code-block:: c * Step 4 : Free memory after use .. code-block:: c for (int i = 0; i < 2; i++) { for (int j = 0; j < 3; j++) { free( tp[i][j] ); } free( tp[i] ); } free(tp); * Step 5 : See the full program below .. code-block:: c #include #include void fun(int **ptr) { // Access Integers and Change for(int i = 0; i < 3; i++) { for(int j = 0; j < 4; j++) { ptr[i][j] = 999; } } } int main(void) { // Define a triple integer pointer int ***tp; // Allocate memory to create array[2][3][4] tp = malloc(2 * sizeof(int **) ); for (int i = 0; i < 2; i++) { tp[i] = malloc(3 * sizeof(int *) ); for (int j = 0; j < 3; j++) { tp[i][j] = malloc(4 * sizeof(int)); } } // Assign data int data = 99; for (int i = 0; i < 2; i++) { for (int j = 0; j < 3; j++) { for (int k = 0; k < 4; k++) { tp[i][j][k] = data++; } } } printf("----- Before Call By Reference -----\n"); for (int i = 0; i < 2; i++) { for (int j = 0; j < 3; j++) { for (int k = 0; k < 4; k++) { printf("tp[%d][%d][%d] = %d ", i, j, k, tp[i][j][k]); } printf("\n"); } printf("\n"); } fun(tp[1]); printf("----- After Call By Reference -----\n"); for (int i = 0; i < 2; i++) { for (int j = 0; j < 3; j++) { for (int k = 0; k < 4; k++) { printf("tp[%d][%d][%d] = %d ", i, j, k, tp[i][j][k]); } printf("\n"); } printf("\n"); } for (int i = 0; i < 2; i++) { for (int j = 0; j < 3; j++) { free( tp[i][j] ); } free( tp[i] ); } free(tp); return 0; } * Step 5 : Output is as below .. code-block:: c ----- Before Call By Reference ----- tp[0][0][0] = 99 tp[0][0][1] = 100 tp[0][0][2] = 101 tp[0][0][3] = 102 tp[0][1][0] = 103 tp[0][1][1] = 104 tp[0][1][2] = 105 tp[0][1][3] = 106 tp[0][2][0] = 107 tp[0][2][1] = 108 tp[0][2][2] = 109 tp[0][2][3] = 110 tp[1][0][0] = 111 tp[1][0][1] = 112 tp[1][0][2] = 113 tp[1][0][3] = 114 tp[1][1][0] = 115 tp[1][1][1] = 116 tp[1][1][2] = 117 tp[1][1][3] = 118 tp[1][2][0] = 119 tp[1][2][1] = 120 tp[1][2][2] = 121 tp[1][2][3] = 122 ----- After Call By Reference ----- tp[0][0][0] = 99 tp[0][0][1] = 100 tp[0][0][2] = 101 tp[0][0][3] = 102 tp[0][1][0] = 103 tp[0][1][1] = 104 tp[0][1][2] = 105 tp[0][1][3] = 106 tp[0][2][0] = 107 tp[0][2][1] = 108 tp[0][2][2] = 109 tp[0][2][3] = 110 tp[1][0][0] = 999 tp[1][0][1] = 999 tp[1][0][2] = 999 tp[1][0][3] = 999 tp[1][1][0] = 999 tp[1][1][1] = 999 tp[1][1][2] = 999 tp[1][1][3] = 999 tp[1][2][0] = 999 tp[1][2][1] = 999 tp[1][2][2] = 999 tp[1][2][3] = 999 .. _funcs_n_ptrs_int_tp_ex_20: .. tab-set:: .. tab-item:: Example 6 : Call by Reference : Pass address of Double dimension arrays which are part of a Triple dimension array to a function * Step 1 : Consider a triple dimension array created using a integer triple pointer .. code-block:: c // Define a triple integer pointer int ***tp; // Allocate memory to create array[2][3][4] tp = malloc(2 * sizeof(int **) ); for (int i = 0; i < 2; i++) { tp[i] = malloc(3 * sizeof(int *) ); for (int j = 0; j < 3; j++) { tp[i][j] = malloc(4 * sizeof(int)); } } // Assign data int data = 99; for (int i = 0; i < 2; i++) { for (int j = 0; j < 3; j++) { for (int k = 0; k < 4; k++) { tp[i][j][k] = data++; } } } * Step 2 : Pass Address of Double dimension array to function ``fun`` .. code-block:: c fun(&tp[1]); * Step 3.1 : Define function ``fun`` .. code-block:: c void fun(int ***ptr) { } * Step 3.2 : Access and Change integers inside function ``fun`` .. code-block:: c void fun(int ***ptr) { for(int i = 0; i < 3; i++) { for(int j = 0; j < 4; j++) { (*ptr)[i][j] = 999; } } } * Step 4 : Free memory after use .. code-block:: c for (int i = 0; i < 2; i++) { for (int j = 0; j < 3; j++) { free( tp[i][j] ); } free( tp[i] ); } free(tp); * Step 5 : See the full program below .. code-block:: c #include #include void fun(int ***ptr) { // Access Integers and Change for(int i = 0; i < 3; i++) { for(int j = 0; j < 4; j++) { (*ptr)[i][j] = 999; } } } int main(void) { // Define a triple integer pointer int ***tp; // Allocate memory to create array[2][3][4] tp = malloc(2 * sizeof(int **) ); for (int i = 0; i < 2; i++) { tp[i] = malloc(3 * sizeof(int *) ); for (int j = 0; j < 3; j++) { tp[i][j] = malloc(4 * sizeof(int)); } } // Assign data int data = 99; for (int i = 0; i < 2; i++) { for (int j = 0; j < 3; j++) { for (int k = 0; k < 4; k++) { tp[i][j][k] = data++; } } } printf("----- Before Call By Reference -----\n"); for (int i = 0; i < 2; i++) { for (int j = 0; j < 3; j++) { for (int k = 0; k < 4; k++) { printf("tp[%d][%d][%d] = %d ", i, j, k, tp[i][j][k]); } printf("\n"); } printf("\n"); } fun(&tp[1]); printf("----- After Call By Reference -----\n"); for (int i = 0; i < 2; i++) { for (int j = 0; j < 3; j++) { for (int k = 0; k < 4; k++) { printf("tp[%d][%d][%d] = %d ", i, j, k, tp[i][j][k]); } printf("\n"); } printf("\n"); } for (int i = 0; i < 2; i++) { for (int j = 0; j < 3; j++) { free( tp[i][j] ); } free( tp[i] ); } free(tp); return 0; } * Step 5 : Output is as below .. code-block:: c ----- Before Call By Reference ----- tp[0][0][0] = 99 tp[0][0][1] = 100 tp[0][0][2] = 101 tp[0][0][3] = 102 tp[0][1][0] = 103 tp[0][1][1] = 104 tp[0][1][2] = 105 tp[0][1][3] = 106 tp[0][2][0] = 107 tp[0][2][1] = 108 tp[0][2][2] = 109 tp[0][2][3] = 110 tp[1][0][0] = 111 tp[1][0][1] = 112 tp[1][0][2] = 113 tp[1][0][3] = 114 tp[1][1][0] = 115 tp[1][1][1] = 116 tp[1][1][2] = 117 tp[1][1][3] = 118 tp[1][2][0] = 119 tp[1][2][1] = 120 tp[1][2][2] = 121 tp[1][2][3] = 122 ----- After Call By Reference ----- tp[0][0][0] = 99 tp[0][0][1] = 100 tp[0][0][2] = 101 tp[0][0][3] = 102 tp[0][1][0] = 103 tp[0][1][1] = 104 tp[0][1][2] = 105 tp[0][1][3] = 106 tp[0][2][0] = 107 tp[0][2][1] = 108 tp[0][2][2] = 109 tp[0][2][3] = 110 tp[1][0][0] = 999 tp[1][0][1] = 999 tp[1][0][2] = 999 tp[1][0][3] = 999 tp[1][1][0] = 999 tp[1][1][1] = 999 tp[1][1][2] = 999 tp[1][1][3] = 999 tp[1][2][0] = 999 tp[1][2][1] = 999 tp[1][2][2] = 999 tp[1][2][3] = 999 .. _funcs_n_ptrs_int_tp_ex_21: .. tab-set:: .. tab-item:: Example 7 : Call by Reference : Pass Address of Triple Dimension array to a function * Step 1 : Consider a triple dimension array created using a integer triple pointer .. code-block:: c // Define a triple integer pointer int ***tp; // Allocate memory to create array[2][3][4] tp = malloc(2 * sizeof(int **) ); for (int i = 0; i < 2; i++) { tp[i] = malloc(3 * sizeof(int *) ); for (int j = 0; j < 3; j++) { tp[i][j] = malloc(4 * sizeof(int)); } } // Assign data int data = 99; for (int i = 0; i < 2; i++) { for (int j = 0; j < 3; j++) { for (int k = 0; k < 4; k++) { tp[i][j][k] = data++; } } } * Step 2 : Pass Address of Triple Dimension array to a function .. code-block:: c fun(&tp); * Step 3.1 : Define function ``fun`` .. code-block:: c void fun(int ****ptr ) { } * Step 3.2 : Access and change individual integers inside function ``fun`` .. code-block:: c for(int i = 0; i < 2; i++) { for(int j = 0; j < 3; j++) { for(int k = 0; k < 4; k++) { (*ptr)[i][j][k] = 999; } } } * Step 4 : Free memory after use .. code-block:: c for (int i = 0; i < 2; i++) { for (int j = 0; j < 3; j++) { free( tp[i][j] ); } free( tp[i] ); } free(tp); * See full program below .. code-block:: c #include #include void fun(int ****ptr) { //Access and change individual integers for(int i = 0; i < 2; i++) { for(int j = 0; j < 3; j++) { for(int k = 0; k < 4; k++) { (*ptr)[i][j][k] = 999; } } } } int main(void) { // Define a triple integer pointer int ***tp; // Allocate memory to create array[2][3][4] tp = malloc(2 * sizeof(int **) ); for (int i = 0; i < 2; i++) { tp[i] = malloc(3 * sizeof(int *) ); for (int j = 0; j < 3; j++) { tp[i][j] = malloc(4 * sizeof(int)); } } // Assign data int data = 99; for (int i = 0; i < 2; i++) { for (int j = 0; j < 3; j++) { for (int k = 0; k < 4; k++) { tp[i][j][k] = data++; } } } printf("----- Before Call By Reference -----\n"); for (int i = 0; i < 2; i++) { for (int j = 0; j < 3; j++) { for (int k = 0; k < 4; k++) { printf("tp[%d][%d][%d] = %d ", i, j, k, tp[i][j][k]); } printf("\n"); } printf("\n"); } fun(&tp); printf("----- After Call By Reference -----\n"); for (int i = 0; i < 2; i++) { for (int j = 0; j < 3; j++) { for (int k = 0; k < 4; k++) { printf("tp[%d][%d][%d] = %d ", i, j, k, tp[i][j][k]); } printf("\n"); } printf("\n"); } for (int i = 0; i < 2; i++) { for (int j = 0; j < 3; j++) { free( tp[i][j] ); } free( tp[i] ); } free(tp); return 0; } * Output is as below .. code-block:: c ----- Before Call By Reference ----- tp[0][0][0] = 99 tp[0][0][1] = 100 tp[0][0][2] = 101 tp[0][0][3] = 102 tp[0][1][0] = 103 tp[0][1][1] = 104 tp[0][1][2] = 105 tp[0][1][3] = 106 tp[0][2][0] = 107 tp[0][2][1] = 108 tp[0][2][2] = 109 tp[0][2][3] = 110 tp[1][0][0] = 111 tp[1][0][1] = 112 tp[1][0][2] = 113 tp[1][0][3] = 114 tp[1][1][0] = 115 tp[1][1][1] = 116 tp[1][1][2] = 117 tp[1][1][3] = 118 tp[1][2][0] = 119 tp[1][2][1] = 120 tp[1][2][2] = 121 tp[1][2][3] = 122 ----- After Call By Reference ----- tp[0][0][0] = 999 tp[0][0][1] = 999 tp[0][0][2] = 999 tp[0][0][3] = 999 tp[0][1][0] = 999 tp[0][1][1] = 999 tp[0][1][2] = 999 tp[0][1][3] = 999 tp[0][2][0] = 999 tp[0][2][1] = 999 tp[0][2][2] = 999 tp[0][2][3] = 999 tp[1][0][0] = 999 tp[1][0][1] = 999 tp[1][0][2] = 999 tp[1][0][3] = 999 tp[1][1][0] = 999 tp[1][1][1] = 999 tp[1][1][2] = 999 tp[1][1][3] = 999 tp[1][2][0] = 999 tp[1][2][1] = 999 tp[1][2][2] = 999 tp[1][2][3] = 999 .. card:: See Also * Other topics of integer and functions * :doc:`./int` * :doc:`./int_sd_array` * :doc:`./int_dd_array` * :doc:`./int_td_array` * :doc:`./int_sp` * :doc:`./int_dp` * :doc:`./int_tp` * Current Module * :doc:`../funcs_n_ptrs` * Previous Module * :doc:`../../typecasting_n_ptr/typecasting_n_ptr` * Next Module * :doc:`../../memcpy_ptr/memcpy_ptr` * Other Modules * :doc:`../../variable_and_ptr/variable_and_ptr` * :doc:`../../array_n_ptrs/array_n_ptrs` * :doc:`../../malloc_ptr/malloc_ptr` * :doc:`../../const_ptr/const_ptr` * :doc:`../../void_ptr/void_ptr` * :doc:`../../array_of_ptr/array_of_ptr` * :doc:`../../ptr_to_array/ptr_to_array` * :doc:`../../function_ptr/function_ptr` * :doc:`../../pre_incr_ptr/pre_incr_ptr` * :doc:`../../post_incr_ptr/post_incr_ptr` * :doc:`../../pre_decr_ptr/pre_decr_ptr` * :doc:`../../post_decr_ptr/post_decr_ptr`