String length in C

#include <stdio.h>
#include <string.h>

int main()
{
  char a[100];
  int length;

  printf("Enter a string to calculate its length\n");
  gets(a);

  length = strlen(a);

  printf("Length of the string = %d\n", length);

  return 0;
}

Output of program:

String length in C without strlen

You can also find string length without strlen function. We create our function to find it. We scan all the characters in the string if the character isn't a null character then increment the counter by one. Once the null character is found the counter equals the length of the string.

#include <stdio.h>

int main()
{
  char s[1000];
  int c = 0;

  printf("Input a string\n");
  gets(s);

  while (s[c] != '\0')
    c++;

  printf("Length of the string: %d\n", c);

  return 0;
}

Function to find string length:

int string_length(char s[]) {
   int c = 0;

   while (s[c] != '\0')
      c++;

   return c;
}

C program to find length of a string using recursion

#include <stdio.h>

int string_length(char [], int);

int main()
{
  char s[100];
  int l = 0; // Length is initialized to zero

  gets(s);

  printf("Length = %d\n", string_length(s, l));

  return 0;
}

int string_length(char s[], int l) {
  if (s[l] == '\0') // Base condition
    return l;

  l++;
  return (string_length(s, l));
}

Function to find string length using pointers

int string_length(char *s) {
   int c = 0;
 
   while(*s[c] != '\0')
      c++;
   
   return c;
}