String length in C

strlen() :

• Find the length of string.
• Return  +ve integer value (size_t)
• size_t is a datatype represents  “unsigned”

• Prototype is
  • size_t  strlen(char s[]);

#include<stdio.h>
#include<string.h>
int main()
{
	char str[20];
	size_t len;
	
	printf("Enter string : ");
	gets(str);
	
	len = strlen(str);
	printf("Length is : %u \n", len);
	return 0;
}

Finding the length without using pre-defined function:

#include<stdio.h>
int main()
{
	char str[20];
	size_t len=0, i=0;
	
	printf("Enter string : ");
	gets(str);
	
	while(str[i] != '\0')
	{
		len++;
		i++;
	}
	
	printf("Length is : %u \n", len);
	return 0;
}

Finding the length with user function:

#include<stdio.h>
size_t Length(char[]);
int main()
{
	char str[20];
	size_t len=0;
	
	printf("Enter string : ");
	gets(str);
	
	len = Length(str);
	printf("Length is : %u \n", len);
}
size_t Length(char s[])
{	
	size_t i=0;
	while(s[i] != '\0')
	{
		i++;
	}
	return i;
}