C Program to Print the Length of a String using Pointers

Prerequisite: Pointer in C

This article demonstrates the program to find the length of the string using pointers in C.

Examples:

Input : given_string = “geeksforgeeks”
Output : length of the string = 13

Input : given_string = “coding”
Output : length of the string = 6

Approach: In this program, we make use of the (*) dereference operator. The  (*) dereference operator is used to access or modify the value of the memory location pointed by the pointer.

In the below program, in the string_length function, we check if we reach the end of the string by checking for a null represented by ‘\0’.

C

// C program to find length of string
// using pointer arithmetic
#include <stdio.h>

// function to find the length
// of the string through pointers
int string_length(char* given_string)
{
    // variable to store the
    // length of the string
    int length = 0;
    while (*given_string != '\0') {
        length++;
        given_string++;
    }

    return length;
}

// Driver function
int main()
{
    // array to store the string
    char given_string[] = "GeeksforGeeks";

    printf("Length of the String: %d",
           string_length(given_string));
    return 0;
}

Output

Length of the String: 13

Time Complexity: O(N)
Auxiliary Space: O(1)

where N is the length of the string.