strlen C Library Function

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The function size_t strlen(const char *str);calculates the length of a string. The length of a C string is the number of character before terminating null character(‘\0’).

Function prototype of strlen

size_t strlen(const char *str);
  • str : This is the string whose length is to be found.

Return value of strlen

This function returns the length of string.

C program using strlen function

The following program shows the use of strlen function to find the length of string.

strlen C Library Function

#include <stdio.h>
#include <string.h>
#include <conio.h>
 
int main()
{
   char string[100];
   int length;
    
   printf("Enter a string\n");
   scanf("%s", &string);
    
   length = strlen(string);
 
   printf("Length of %s is %d", string, length);
    
   getch();
   return(0);
}

Output

Enter a string
TechCrashCourse
Length of TechCrashCourse is 15