C Program to find Length of a String using Pointer

In this article, we have explained the approach to find the length of a string using Pointer in C Programming Language.

Table of contents:

1. Approach
2. C Program to find Length of a String using Pointer

Understand:

• Understand Pointers in C in depth

Approach

In C programming language, a string is an array of characters that is a character pointer. A string in C is as follows:

char* string

One can get the current character as "*p". This refers to the first character. On incrementing p (p++), *p is the second character and so on.

The last character of a string is always a Null Character that is \0.

So, the approach to find Length of a String using Pointer is as follows:

• Get the string as a character array
• Compare the current character at current pointer with \0
• Increment pointer to get to next character
• If current character is not null, increment counter else current counter is the length of string.

We can traverse an array by just incrementing its pointer:

while (true) {
  p++;
}

The current needs to be compared with null character:

*p = '\0';

If p is a pointer, then the data at the pointer location is accessed using *p.

In C, this approach can be implemented as follows as a function:

int getLength(char* p) {
   int count = 0;
   while (*p != '\0') {
      count++;
      p++;
   }
   return count;
}

C Program to find Length of a String using Pointer

Following is the complete C Program to find Length of a String using Pointer:

// Part of iq.opengenus.org
#include<stdio.h>
int getLength(char*p) {
   int count = 0;
   while (*p != '\0') {
      count++;
      p++;
   }
   return count;
}
int main() {
   char str[20] = "OpenGenus";
   int length = 0;
   length = getLength(str);
   printf("The length of the string \"%s\" is %d", str, length);
   return 0;
}

Output:

The length of the string "OpenGenus" is 9

With this article at OpenGenus, you must have the complete idea of how to find implement a C Program to find Length of a String using Pointer.