Basics of Integer Single Dimension Array

In this section, you are going to learn

What are the basic properties of a integer 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,

int array_name[Column];

Consider a Integer Single Dimension Array

int a[10];

Let us answer few basic questions in this array

How many integers can be stored in this array ?

See Answer

Number of Integers = 10

How many bytes are there in this array ?

See Answer

Number of Bytes = 10 * sizeof(int) = 10 * 4 = 40 Bytes

What is the sizeof the array ?

See Answer

sizeof(a) = Number of Bytes = 10 * sizeof(int) = 10 * 4 = 40 Bytes

How many bits can be stored in this array ?

See Answer

Number of Bits = sizeof(a) * 8 = 40 * 8 = 320 bits

Let us now explore basic examples of single dimension array !

  • Step 1 : Define a Single Dimension Array

int a[10] = { 0, 1, 2, 3, 4, 5, 6, 7, 8, 9 };

  • Step 2 : Access and Print individual integers

for (int i = 0; i < sizeof(a) / sizeof(a[0]); i++)
{
        printf("%d ", a[i]);
}

  • Step 4 : See the full program below

#include <stdio.h>
#include <string.h>

int main(void)
{
        int a[10] = { 0, 1, 2, 3, 4, 5, 6, 7, 8, 9 };

        // Print individual integers
        printf("---------- Access and Print Individual Integers --------------\n");
        for (int i = 0; i < sizeof(a) / sizeof(a[0]); i++)
        {
                printf("%d ", a[i]);
        }
        printf("\n");

        return 0;
}

  • Step 5 : Output is as below

---------- Access and Print Individual Integers --------------
0 1 2 3 4 5 6 7 8 9

Let us now explore Double Dimension Array in depth !

Consider a integer single dimension array

int a[10];

Then below are the properties

  • Expressions

  • Synonyms

  • typeof(expression)

  • sizeof(expression)

  • fun(expression)

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

Expression

Description

a[0]

  • a[0] is first integer in the array

a[1]

  • a[1] is second integer in the array

a[9]

  • a[9] is tenth integer in the array

&a[0]

  • &a[0] is address of first integer

&a[1]

  • &a[1] is address of second integer

&a[9]

  • &a[9] is address of tenth integer

*a

  • *a is first integer in the array

*(a + 1)

  • *(a + 1) is second integer in the array

*(a + 9)

  • *(a + 9) is tenth integer in the array

a

  • a is address of first integer

  • a is an array of ten integers

a + 1

  • a + 1 is address of second integer

  • a is an array of nine integers

a + 9

  • a + 9 is address of tenth integer

  • a + 9 is an array of one integer

&a

  • &a is the address of array of integers

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

Finding the type of an expression is easy. See below

Expression

Type

Description

a[0]

int

  • a[0] is a integer

  • Hence type is int

a[1]

int

  • a[1] is a integer

  • Hence type is int

a[9]

int

  • a[9] is a integer

  • Hence type is int

&a[0]

int *

  • a[0] is a integer

  • typeof(a[0]) is int

  • Hence typeof(&a[0]) is int *

&a[1]

int *

  • a[1] is a integer

  • typeof(a[1]) is int

  • Hence typeof(&a[1]) is int *

&a[9]

int *

  • a[9] is a integer

  • typeof(a[9]) is int

  • Hence typeof(&a[9]) is int *

*a

int

  • *a is a integer

  • Hence type is int

*(a + 1)

int

  • *(a + 1) is a integer

  • Hence type is int

*(a + 9)

int

  • *(a + 9) is a integer

  • Hence type is int

a

int *

  • a is equal to &a[0]

  • Hence typeof(a) is int *

a + 1

int *

  • a + 1 is equal to &a[1]

  • Hence typeof(a + 1) is int *

a + 9

int *

  • a + 9 is equal to &a[9]

  • Hence typeof(a + 9) is int *

&a

int (* )[10]

  • &a is address of complete array

sizeof(expression)

size

Description

sizeof(a[0])

4 Bytes

a[0] is a integer

sizeof(a[1])

4 Bytes

a[1] is a integer

sizeof(a[9])

4 Bytes

a[9] is a integer

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)

4 Bytes

*a is a integer

sizeof(*(a + 1) )

4 Bytes

*(a + 1) is a integer

sizeof(*(a + 9) )

4 Bytes

*(a + 9) is a integer

sizeof(a)

40 Bytes

a is an array of 10 integers

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>

int main(void)
{
        int 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])            = 4
sizeof(a[1])            = 4
sizeof(a[9])            = 4
sizeof(&a[0])           = 8
sizeof(&a[1])           = 8
sizeof(&a[9])           = 8
sizeof(*a)              = 4
sizeof( *(a + 1) )      = 4
sizeof( *(a + 9) )      = 4
sizeof(a)               = 10
sizeof(a + 1)           = 8
sizeof(a + 9)           = 8
sizeof(&a)              = 8

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(int x) { }

  • Call by Value

fun(a[1])

void fun(int x) { }

  • Call by Value

fun(a[9])

void fun(int x) { }

  • Call by Value

fun(&a[0])

void fun(int *p) { }

  • Call by Reference

fun(&a[1])

void fun(int *p) { }

  • Call by Reference

fun(&a[9])

void fun(int *p) { }

  • Call by Reference

fun(*a)

void fun(int x) { }

  • Call by Value

fun(*(a + 1))

void fun(int x) { }

  • Call by Value

fun(*(a + 9))

void fun(int x) { }

  • Call by Value

fun(a)

void fun(int *p) { }

  • Call by Reference

fun(a + 1)

void fun(int *p) { }

  • Call by Reference

fun(a + 9)

void fun(int *p) { }

  • Call by Reference

fun(&a)

void fun(int (*p) [10] ) { }

  • Call by Reference

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

See Also