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C program to calculate length of the string without using strlen()

In this program, we will calculate length of the string without using strlen() function, strlen() is a library function of string.h that returns length of the string.

Here, we will count the total number of characters available in a string and will not use strlen().

Logic

Read a string
Create a function and pass string within it
Take a counter as length (that will store the length of the string), initialize with 0
Run a loop until NULL character is not found
Increase the counter (length)
As NULL founds return the length

C example to calculate string length

#include <stdio.h>

/*function to return length of the string*/
int stringLength(char*);

int main()
{
	char str[100]={0};
	int length;

	printf("Enter any string: ");
	scanf("%s",str);
	
	/*call the function*/
	length=stringLength(str);
	
	printf("String length is : %d\n",length);

	return 0;
}

/*function definition...*/
int stringLength(char* txt)
{
	int i=0,count=0;
	
	while(txt[i++]!='\0'){
		count+=1;
	}
	
	return count;
}

Output

Enter any string: IncludeHelp 
String length is : 11