Find the length of a string without using any loops and string.h in C. Your program is supposed to behave in following way: 

Enter a string: ProgrammingShark (Say user enters ProgrammingShark)
Entered string is: ProgrammingShark
Length is: 13

You may assume that the length of entered string is always less than 100.
The following is the solution. 

C

#include 
int main()
{
	
	// entered string
	char ch[50] = "ProgrammingShark";

	// printing entered string
	printf("Entered String is:");

	// returns length of string
	// along printing string
	int len
		= printf("%s\n", ch);

	printf("Length is:");

	// printing length
	printf("%d", len - 1);
}

Output

Entered String is:ProgrammingShark
Length is:13

The idea is to use return values of printf(). 
printf() returns the number of characters successfully written on output.
In the above program we just use the property of printf() as it returns the number of characters entered in the array string. 

Another way of finding the length of a string without using string.h or loops is Recursion. 
The following program does the work of finding a length of a string using recursion. 

// C program for the above approach
#include 

void LengthofString(int n,char *string)
{
	if(string[n] == '\0')
	{
		printf("%i",n);
		return;
	}
	
	LengthofString(n+1,string);
	//printf("%c",string[n]);
}

int main()
{
	char string[100];
	printf("Give a string : \n");
	scanf("%s",string);
	printf("Entered string is:%s\n", string);
	LengthofString(0,string);
	
	return 0;
}

Output

Give a string : 
Entered string is:0
1

The Function LengthofString calls itself until the character of string is’nt a null character it calls itself, when it calls itself it increases the value of the variable ‘n’ which stores number of times the function has been called and when it encounters the null character the function prints the value of ‘n’ and returns back in the same direction in which it was executed.