Basics of Structure Single Dimension Array

In this section, you are going to learn

What are the basic properties of a structure single dimension array ?

What are the different expressions of single dimension array ?

What are synonymous expresions of single dimension array ?

How to find sizeof() of expressions of single dimenstion array ?

Topics in this section,

• Structure Single Dimension Array : Syntax

• Structure Single Dimension Array : FAQs

• Structure Single Dimension Array : Basic Examples

  • Structure Single Dimension Array : Basic Example 1

• Structure Single Dimension Array : Basic Properties

• Structure Single Dimension Array : Basic Expressions

• Structure Single Dimension Array : Synonym Expressions

• Structure Single Dimension Array : typeof(expression)

• Structure Single Dimension Array : sizeof(expression)

• Structure Single Dimension Array : fun(expression)

• Structure Single Dimension Array : All Examples of Function Calls

Structure Single Dimension Array : Syntax

struct XYZ array_name[Column];

Structure Single Dimension Array : FAQs

Consider a Structure Single Dimension Array

struct XYZ {
        int x;
        int y;
        int z;
};

struct XYZ a[4];

Let us answer few basic questions in this array

How many structures can be stored in this array ?

See Answer

Number of Structures = 4

How many bytes are there in this array ?

See Answer

Number of Bytes = 4 * sizeof(struct XYZ) = 4 * 12 = 48 Bytes

What is the sizeof the array ?

See Answer

sizeof(a) = Number of Bytes = 4 * sizeof(struct XYZ) = 4 * 12 = 48 Bytes

How many bits can be stored in this array ?

See Answer

Number of Bits = sizeof(a) * 8 = 48 * 8 = 384 bits

How do you initialise single dimension array during declaration ?

See Answer

struct XYZ a[4] = {
        {.x = 11, .y = 22, .z = 33},
        {.x = 44, .y = 55, .z = 66},
        {.x = 77, .y = 88, .z = 99},
        {.x = 12, .y = 34, .z = 56}
};

Structure Single Dimension Array : Basic Examples

Let us now explore basic examples of single dimension array !

Structure Single Dimension Array : Basic Example 1

• Step 1 : Define a Single Dimension Array

struct XYZ {
        int x;
        int y;
        int z;
};

struct XYZ a[4] = {
        {.x = 11, .y = 22, .z = 33},
        {.x = 44, .y = 55, .z = 66},
        {.x = 77, .y = 88, .z = 99},
        {.x = 12, .y = 34, .z = 56},
};

• Step 2 : Access and Print individual structures

for (int i = 0; i < sizeof(a) / sizeof(a[0]); i++)
{
        printf("a[%d].x = %d ", i, a[i].x);
        printf("a[%d].y = %d ", i, a[i].y);
        printf("a[%d].z = %d ", i, a[i].z);
        printf("\n");
}

• Step 3 : See the full program below

#include <stdio.h>

struct XYZ {
        int x;
        int y;
        int z;
};

int main(void)
{
        struct XYZ a[4] = {
                {.x = 11, .y = 22, .z = 33},
                {.x = 44, .y = 55, .z = 66},
                {.x = 77, .y = 88, .z = 99},
                {.x = 12, .y = 34, .z = 56},
        };

        for (int i = 0; i < sizeof(a) / sizeof(a[0]); i++)
        {
                printf("a[%d].x = %d ", i, a[i].x);
                printf("a[%d].y = %d ", i, a[i].y);
                printf("a[%d].z = %d ", i, a[i].z);
                printf("\n");
        }

        return 0;
}

• Step 4 : Output is as below

a[0].x = 11 a[0].y = 22 a[0].z = 33

a[1].x = 44 a[1].y = 55 a[1].z = 66

a[2].x = 77 a[2].y = 88 a[2].z = 99

a[3].x = 12 a[3].y = 34 a[3].z = 56

Structure Single Dimension Array : Basic Properties

Let us now explore Double Dimension Array in depth !

Consider a structure single dimension array

struct XYZ a[10];

Then below are the properties

• Expressions

• Synonyms

• typeof(expression)

• sizeof(expression)

• fun(expression)

Structure Single Dimension Array : Basic Expressions

Know what are the possible expressions and how to properly call them !

Expression	Description
a[0]	a[0] is first structure in the array
a[1]	a[1] is second structure in the array
a[9]	a[9] is tenth structure in the array
&a[0]	&a[0] is address of first structure
&a[1]	&a[1] is address of second structure
&a[9]	&a[9] is address of tenth structure
*a	*a is first structure in the array
*(a + 1)	*(a + 1) is second structure in the array
*(a + 9)	*(a + 9) is tenth structure in the array
a	a is address of first structure a is an array of ten structures
a + 1	a + 1 is address of second structure a is an array of nine structures
a + 9	a + 9 is address of tenth structure a + 9 is an array of one structure
&a	&a is the address of array of structures

Structure Single Dimension Array : Synonym Expressions

Synonyms : Which can be used interchangeably !

Programmatically few expressions are one and the same ! Let us learn them

Expression	Synonyms
a[0]	*a
a[1]	*(a + 1)
a[9]	*(a + 9)
&a[0]	a + 0 a
&a[1]	a + 1
&a[9]	a + 9
*a	a[0]
*(a + 1)	a[1]
*(a + 9)	a[9]
a	&a[0]
a + 1	&a[1]
a + 9	&a[9]
&a	&a

Structure Single Dimension Array : typeof(expression)

Finding the type of an expression is easy. See below

Expression	Type	Description
a[0]	struct XYZ	a[0] is a structure Hence type is struct XYZ
a[1]	struct XYZ	a[1] is a structure Hence type is struct XYZ
a[9]	struct XYZ	a[9] is a structure Hence type is struct XYZ
&a[0]	struct XYZ *	a[0] is a structure typeof(a[0]) is struct XYZ Hence typeof(&a[0]) is struct XYZ *
&a[1]	struct XYZ *	a[1] is a structure typeof(a[1]) is struct XYZ Hence typeof(&a[1]) is struct XYZ *
&a[9]	struct XYZ *	a[9] is a structure typeof(a[9]) is struct XYZ Hence typeof(&a[9]) is struct XYZ *
*a	struct XYZ	*a is a structure Hence type is struct XYZ
*(a + 1)	struct XYZ	*(a + 1) is a structure Hence type is struct XYZ
*(a + 9)	struct XYZ	*(a + 9) is a structure Hence type is struct XYZ
a	struct XYZ *	a is equal to &a[0] Hence typeof(a) is struct XYZ *
a + 1	struct XYZ *	a + 1 is equal to &a[1] Hence typeof(a + 1) is struct XYZ *
a + 9	struct XYZ *	a + 9 is equal to &a[9] Hence typeof(a + 9) is struct XYZ *
&a	struct XYZ (* )[10]	&a is address of complete array

Structure Single Dimension Array : sizeof(expression)

sizeof(expression)	size	Description
sizeof(a[0])	12 Bytes	a[0] is a structure
sizeof(a[1])	12 Bytes	a[1] is a structure
sizeof(a[9])	12 Bytes	a[9] is a struct XYZcter
sizeof(&a[0])	8 Bytes	&a[0] is address / pointer
sizeof(&a[1])	8 Bytes	&a[1] is address / pointer
sizeof(&a[9])	8 Bytes	&a[9] is address / pointer
sizeof(*a)	12 Bytes	*a is a structure
sizeof(*(a + 1) )	12 Bytes	*(a + 1) is a structure
sizeof(*(a + 9) )	12 Bytes	*(a + 9) is a structure
sizeof(a)	120 Bytes	a is an array of 10 structures
sizeof(a + 1)	8 Bytes	a + 1 is address / pointer
sizeof(a + 9)	8 Bytes	a + 9 is address / pointer
sizeof(&a)	8 Bytes	&a is address / pointer

• See the full program below

#include <stdio.h>

struct XYZ {
        int x;
        int y;
        int z;
};

int main(void)
{
        struct XYZ a[10];

        printf("sizeof(a[0])            = %d\t\n", (int) sizeof(a[0]) );
        printf("sizeof(a[1])            = %d\t\n", (int) sizeof(a[1]) );
        printf("sizeof(a[9])            = %d\t\n", (int) sizeof(a[9]) );
        printf("sizeof(&a[0])           = %d\t\n", (int) sizeof(&a[0]) );
        printf("sizeof(&a[1])           = %d\t\n", (int) sizeof(&a[1]) );
        printf("sizeof(&a[9])           = %d\t\n", (int) sizeof(&a[9]) );
        printf("sizeof(*a)              = %d\t\n", (int) sizeof(*a) );
        printf("sizeof( *(a + 1) )      = %d\t\n", (int) sizeof( *(a + 1) ) );
        printf("sizeof( *(a + 9) )      = %d\t\n", (int) sizeof( *(a + 9) ) );
        printf("sizeof(a)               = %d\t\n", (int) sizeof(a) );
        printf("sizeof(a + 1)           = %d\t\n", (int) sizeof(a + 1) );
        printf("sizeof(a + 9)           = %d\t\n", (int) sizeof(a + 9) );
        printf("sizeof(&a)              = %d\t\n", (int) sizeof(&a) );

        return 0;
}

• Output is as below on 64 bit OS

sizeof(a[0])            = 12
sizeof(a[1])            = 12
sizeof(a[9])            = 12
sizeof(&a[0])           = 8
sizeof(&a[1])           = 8
sizeof(&a[9])           = 8
sizeof(*a)              = 12
sizeof( *(a + 1) )      = 12
sizeof( *(a + 9) )      = 12
sizeof(a)               = 120
sizeof(a + 1)           = 8
sizeof(a + 9)           = 8
sizeof(&a)              = 8

Structure Single Dimension Array : fun(expression)

If fun(x) is the function call, then fun(typeof(x)) is the prototype / definition

Function Call	Function Definition	Observations
fun(a[0])	void fun(struct XYZ x) { }	Call by Value
fun(a[1])	void fun(struct XYZ x) { }	Call by Value
fun(a[9])	void fun(struct XYZ x) { }	Call by Value
fun(&a[0])	void fun(struct XYZ *p) { }	Call by Reference
fun(&a[1])	void fun(struct XYZ *p) { }	Call by Reference
fun(&a[9])	void fun(struct XYZ *p) { }	Call by Reference
fun(*a)	void fun(struct XYZ x) { }	Call by Value
fun(*(a + 1))	void fun(struct XYZ x) { }	Call by Value
fun(*(a + 9))	void fun(struct XYZ x) { }	Call by Value
fun(a)	void fun(struct XYZ *p) { }	Call by Reference
fun(a + 1)	void fun(struct XYZ *p) { }	Call by Reference
fun(a + 9)	void fun(struct XYZ *p) { }	Call by Reference
fun(&a)	void fun(struct XYZ (*p) [10] ) { }	Call by Reference

Structure Single Dimension Array : All Examples of Function Calls

Read more about function calls and conventions of Functions and Structure Single Dimension Array

See Also

• Other topics of character and functions

  • Basics of Structure Single Dimension Array

  • Basics of Structure Double Dimension Array

  • Basics of Structure Triple Dimension Array

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