C Exercises: Find the length of a string without using the library function

Last update on July 31 2025 05:46:39 (UTC/GMT +8 hours)

58. Find String Length Without Library Function

Write a C program to find the length of a string without using the library function.

This C program takes a string as input and iterates through each character until it encounters the null terminator '\0', incrementing a counter variable for each character. After iterating through the entire string, it prints the count of characters as the length of the string.

Visual Presentation:

Sample Solution:

C Code:

#include <stdio.h>   // Include the standard input/output header file. 
#include <string.h>
void main()
{
    // Variable declarations
char str1[50];
int i, l = 0;
    // Prompting user for input
printf("\n\nFind the length of a string:\n ");
printf("-------------------------------------\n");
    // Getting user input
printf("Input a string : ");
scanf("%s", str1);
    // Loop to count characters in the string
for (i = 0; str1[i] != '\0'; i++)
    {
l++;
    }
    // Printing the length of the string
printf("The string contains %d number of characters. \n", l);
printf("So, the length of the string %s is : %d\n\n", str1, l);
}

Output:

Find the length of a string:                                                                                  
 -------------------------------------                                                                        
Input a string : welcome                                                                                      
The string contains 7  number of characters.                                                                  
So, the length of the string welcome is : 7

Flowchart:

For more Practice: Solve these Related Problems:

Write a C program to calculate the length of a string using pointer arithmetic without using strlen().
Write a C program to find the length of a string recursively without any loop constructs.
Write a C program to compute the length of a string by traversing each character without standard library functions.
Write a C program to determine the length of a string and then compare it with a user-provided value.

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