C String Functions - C strlen

Returns the length of a string.

Computes the length of the string str up to but not including the terminating null character.

Returns the number of characters in the string.

Prototype

size_t strlen(const char *str );

Parameter

This function has the following parameter.

str: C string.

Return

The length of string.

Example


#include <stdio.h>
#include <string.h>
/*from  w ww .j a  v a 2  s . c om*/
int main (){
  char szInput[256];
  printf ("Enter a sentence: ");
  gets (szInput);
  printf ("%u characters long.\n",(unsigned)strlen(szInput));
  return 0;
}

The code above generates the following result.

Example 2

strlen() function gives the length of a string in characters.


#include <stdio.h> 
#include <string.h>      /* provides strlen() prototype */ 
#define PRAISE "You are an extraordinary being." 
int main(void) { 
    char name[40]; 
 /*  www .  j a v a2 s  . c  o m*/
    printf("What's your name? "); 
    scanf("%s", name); 
    printf("Hello, %s. %s\n", name, PRAISE); 
    printf("Your name of %zd letters occupies %zd memory cells.\n", strlen(name), sizeof name); 
    printf("%zd letters ", strlen(PRAISE)); 
    printf("occupies %zd cells.\n", sizeof PRAISE); 
 
    return 0; 
}

The code above generates the following result.

Example 3


#include <string.h>
#include <stdio.h>
 /* ww w .java2s  .  c  o  m*/
int main(void){
    const char str[] = "this is a test";
 
    printf("without null character: %zu\n", strlen(str));
    printf("with null character:    %zu\n", sizeof str);
 
    printf("without null character: %zu\n", strnlen_s(str, sizeof str));

}

The code above generates the following result.