Calculator H.E.L.P.

program crashes when i try to enter the first operation. any help is great. Here's the code:

#include <iostream>
using namespace std; // so we dont have to use std

int main () // start function
{
double num1; // first number
double num2; // second number
double answer; // answer
char op1; // first operation
char op2; // second operation
char quit; // quit option
char op;

do // start do loop
{
cout << " welcome to my calculator\n"; // welcom screen

cout << " enter first number\n"; // user enters first number

cin >> num1; // input users answer

cout << "enter an operation ( + - * or / ) \n";

cin >> op1;

do // second loop
{

switch (op) // start of switch
{

cout << "enter another number\n";
cin >> num2;

case '+' : (answer = num1 + num2);
cout << "total is "; cout << answer;
cout << "enter another operation ( + - * / or =) \n";
cin >> op2;
if (op2 != '=') (answer=num1);
break;

case '-' : (answer = num1 - num2);
cout << "total is "; cout << answer;
cout << "enter another operation ( + - * / or =) \n";
cin >> op2;
if (op2 == '=')
break;

case '*' : (answer = num1 * num2);
cout << "total is "; cout << answer;
cout << "enter another operation ( + - * / or =) \n";
cin >> op2;
if (op2 != '=') (answer=num1);
break;

case '/' : (answer = num1 / num2);
cout << "total is "; cout << answer;
cout << "enter another operation ( + - * / or =) \n";
cin >> op2;
if (op2 != '=') (answer=num1);
break;
}
} while (op2 != '=');

cout << "your answer is "; cout << answer; cout << endl;
cout << "Quit? (Y or N) ";
cin >> quit;

} while (quit != 'N');

return 0;
}

cppmatt (37)

You are switching on op, but op is never initialized or set.

anonymouscoder6 (42)

Have you even tried compling your code? Looks like you haven't.

Whats this??
if (op2 != '=') (answer=num1);

cppmatt (37)

anonymouscoder6,

I believe this line is o.k., since op2 is supposed to be a char. The user could enter '=' at the command prompt. If all of the variables were initialized and/or set, I believe the code will compile and run as is.

anonymouscoder6 (42)

CPPMATT,
I was not talking about the '=', I was referring to the statement after condition check. Isn't answer=num1 supposed to be in curly braces rather than ()?

cppmatt (37)

anonymouscoder6,

No, this need not be in curly braces. An IF statement can execute without curly braces, just like this:

1
2

 if (num>x)
     num-=1;

Now the compiler doesn't care if we instead write:

1
2

if (num>x)
   (num-=1);

And since the compiler ignores white space, this is equivalent to:

if (num>x) (num-=1);

I agree that it is bad style and makes the code hard to read.

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Calculator H.E.L.P.