Using - C
  
 Source Code
  

    
      #include<stdio.h>
      
void main() {
	char str[1024];
	int i=0, length=0;
	printf("Enter the String:  ");
	gets(str);
	while(str[i] != '\0') {
		length++;
		i++;
	}
	
	printf("Length of the given string:  %d",length);
}
    

Enter the String:  programmer OP!
Length of the given string:  14

        
Using - C++
        
 Source Code
        

        
          #include<iostream>
using namespace std;

int main() {
	string str;
	int i=0, length=0;
	cout<< "Enter the String:  ";
	getline(cin,str);
	
	while(str[i] != '\0') {
		length++;
		i++;
	}
	
	cout<< "Length of the given string:  "<< length;
		
	return 0;
}
      

Enter the String:  welcome to GCCxCSD
Length of the given string:  18