C Exercises: Calculate the length of the string

Last update on October 16 2025 11:44:03 (UTC/GMT +8 hours)

10. String Length Using Pointer

Write a program in C to calculate the length of a string using a pointer.

Visual Presentation:

Sample Solution:

C Code:

#include <stdio.h>

// Function to calculate the length of the string
int calculateLength(char*); // Function prototype

int main() 
{
   char str1[25];
   int l;

   printf("\n\n Pointer : Calculate the length of the string :\n"); 
   printf("---------------------------------------------------\n");

   printf(" Input a string : ");
   fgets(str1, sizeof str1, stdin); // Input the string from the user

   l = calculateLength(str1); // Get the length of the input string
   printf(" The length of the given string %s is : %d ", str1, l-1); // Display the length of the string
   printf("\n\n");
}

// Function to calculate the length of the string
int calculateLength(char* ch) // Takes a pointer to the first character of the string
{
   int ctr = 0;

   while (*ch != '\0') // Loop until the null character '\0' is found
   {
      ctr++; // Increment the counter for each character encountered
      ch++; // Move to the next character in the string
   }

   return ctr; // Return the total count of characters (excluding the null character)
}

Sample Output:

 Pointer : Calculate the length of the string :                                                               
---------------------------------------------------                                                           
 Input a string : w3resource                                                                                  
 The length of the given string w3resource                                                                    
 is : 10

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 determine the length of a string recursively by advancing a pointer.
• Write a C program to compute the length of a string and then compare it with a user-specified value.
• Write a C program to find the string length and then reverse the string using pointer manipulation.

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