Array v/s String in C

March 18, 2025

Array v/s String

Array is defined as a contiguous block of memory in which similar type of data is stored. Array indexing starts with size 0 and ends with size -1. String is defined as a sequence of character which terminates with a null character.

Array v/s String in C

Array v/s String Declaration in C:

Array Declaration

  [arr_size]={value 1, value 2, value 3,…,value n-1};

String Declaration

char str[] = "string_name";

Difference between Array and String

ArrayString
Array is a collection of elements of similar data type.Strings are a sequence of character of a single data type.
Array can store a set of integer, character, float etc.String can store a set of characters only.
Array has a fixed size and it cannot be changed after declaration.String has fixed size but it can be changed using char pointer.

Arrays don’t need to end with the null character.

String ends with the null character.
Array can be one dimensional, two dimensional and multidimensional.String are always two dimensional.

Arrays in C

1 Dimensional Array in C

 2 Dimensional Array in C

Strings in C

Functions in C

Array: Example 1

Run
#include <stdio.h>
int main() {
    int values[6] = {2,4,6,8,4,9};
    printf("Displaying integers: ");
    for(int i = 0; i < 6; ++i) {
        printf("%d ", values[i]);
    }
    return 0;
}

Output

Displaying integers: 2 4 6 8 4 9

Array: Example 2

Run

#include<stdio.h>
int main ()
{
    int i, j, temp;
    int a[15] = { 15, 33, 67, 43, 89, 11, 99, 56, 55, 46, 78, 93, 22, 44, 66 };
    for (i = 0; i < 15; i++)
        {
            for (j = i + 1; j < 15; j++)
        {
            if (a[j] > a[i])
                {
                    temp = a[i];
                    a[i] = a[j];
                    a[j] = temp;
                }
        }
        }
    printf ("Sorted Elements are = \n");
    for (i = 0; i < 15; i++)
        {
            printf ("%d ", a[i]);
        }
    return 0;
}

Output

Sorted Elements are =
99 93 89 78 67 66 56 55 46 44 43 33 22 15 11

Array: Example 3

Run 
#include<stdio.h>
int main ()
{
    int i, largest, sec_largest;
    int arr[10] = { 2, 1, 5, 4, 87, 76, 89, 99, 80, 10 };
    largest = arr[0];
    sec_largest = arr[1];
    for (i = 0; i < 10; i++) 
    { 
        if (arr[i] > largest)
        {
            sec_largest = largest;
            largest = arr[i];
        }
            else if (arr[i] > sec_largest && arr[i] != largest)
        {
            sec_largest = arr[i];
        }
    }
    printf ("largest = %d\nSecond largest = %d", largest, sec_largest);
    return 0;
}

Output

largest = 99
Second largest = 89

String: Example 1

Run 
#include<stdio.h>
int main ()
{
    char s[10] = "PrepInsta";
    int i = 0;
    int count = 0;
    while (i < 10)
        {
           if (s[i] == 'a' || s[i] == 'e' || s[i] == 'i' || s[i] == 'u'
|| s[i] == 'o' || s[i]== 'A' || s[i] == 'E' || s[i] == 'I' || s[i] == 'O' || s[i] == 'U')
        {
            count++;
        }
            i++;
        }
    printf ("The number of vowels = %d", count);
    return 0;
}

Output

The number of vowels = 3

String: Example 2

Run

#include<stdio.h>
int main ()
{
    char s[9] = "atsnIperP"; // declaration of string
    printf ("The reverse string is :");
    for (int i = 8; i >= 0; i--)
        {
            printf ("%c", s[i]);
        }
    return 0;
}

Output

The reverse string is :PrepInsta

String: Example 3

Run
#include <stdio.h>
int main ()
{
    char s[10] = "PrepInsta";
    int i = 0;
    int count = 0;
    while (i < 10)
        {
            if (s[i] == 'a' || s[i] == 'e' || s[i] == 'i' || s[i] == 'u'
|| s[i] == 'o' || s[i] == 'A' || s[i] == 'E' || s[i] == 'I'
|| s[i] == 'O' || s[i] == 'U')
        {
            printf ("The first vowel in the string : %c", s[i]);
            return 0;
        }
            i++;
        }
    printf ("There is no vowel in the string");
    return 0;
}

Output

The first vowel in the string : e