09_basic_calculator.cpp

/*
    Problem: Write a program that works as a simple calculator.
                1.It reads a character (ch)
                2.If ch is among '+', '-', '*', '/' or '%' it furthur takes two numbers (N1 and N2 as input). It then performs appropriate appropriate operation between numbers and print the number.
                3.If ch is 'X' or 'x', the program terminates.
                4.If ch is any other character, the program should print 'Invalid operation. Try again.' and seek inputs again (starting from character).
             Write code to achieve above functionality.

    Constraints:  0 <= Input integers <= 100000000
                  (It is assured that the second integer provided for division and modulo operations will not be 0.)
    
    Output Format: Output a single integer output for the operations in a new line each.

    Sample Input:   * 
                    1 
                    2 
                    / 
                    4 
                    2 
                    + 
                    3 
                    2 
                    ; 
                    X
    
    Sample Output:  2 
                    2 
                    5 
                    Invalid operation. Try again.

    Explanation:   Maybe use a do-while.

*/

#include<iostream>
using namespace std;

int main() {
	char ch;
	cin>>ch;

	int num1, num2;
	while(ch!='x' and ch!='X'){
		if(ch=='+'){
			cin>>num1>>num2;
			cout<<num1+num2<<endl;
		}else if(ch=='-'){
			cin>>num1>>num2;
			cout<<num1-num2<<endl;
		}else if(ch=='*'){
			cin>>num1>>num2;
			cout<<num1*num2<<endl;
		}else if(ch=='/'){
			cin>>num1>>num2;
			cout<<num1/num2<<endl;
		}else if(ch=='%'){
			cin>>num1>>num2;
			cout<<num1%num2<<endl;
		}else{
			cout<<"Invalid operation. Try again."<<endl;
		}
		cin>>ch;
	}
	return 0;
}

/*
    Simply Put a loop and take input operator and then take input of two digits and then perform the operation till the user inputs 'x' or 'X'.
*/