Length of a String without Using the strlen Function in C - Coding

A string in C is an array that stores a sequence of characters terminated by a NULL character. In this article, we will learn how to calculate the length of a string without using the inbuilt strlen method in C.

For Example,

Input: str= "Hello, world!"

Output: Length of string is 13

Find the Length of String without strlen in C

To find the length of a string, we generally use the strlen() function provided in the <string.h> header. But we can also find the length of the string simply by using a loop to iterate through a given string and keep counting the characters until the null terminator(‘\0’) is encountered.

Note: The NULL character ‘\0’ is not counted in the string length.

C Program to Find Length of String without strlen Function

C

// C Program to Calculate the Length of a String without 
// strlen function 
#include <stdio.h> 
  
// Function to calculate the length of a string 
int string_length(char* str) 
{ 
    int len = 0; 
  
    // Iterate through the string until the null terminator 
    // is reached 
    while (*str != '\0') { 
        len++; 
        str++; 
    } 
  
    return len; 
} 
  
int main() 
{ 
    // Declare and initialize a character array 
    char str[] = "Hello, world!"; 
    int length; 
  
    // Calculate the length of the string using the function 
    length = string_length(str); 
  
    // Print the length of the string 
    printf("The length of the string is: %d", length); 
  
    return 0; 
}

Output

The length of the string is: 13

Time Complexity: O(N), where N is the number of character in the string excluding NULL character.
Auxiliary Space: O(1)

Reffered: https://www.geeksforgeeks.org

C Language

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