What's wrong in this code?

**CNewProg** · 08-30-2016

Edit: The code is working now.

Hi all,

This is my first post here. I'm learning C++ by myself, and I'm using the free version of Visual Studio. I have the following code taken from a tutorial, but it gives me an error. I'm not sure why? It says that '*' operand must be a pointer. What does that mean? The code is

Code:

// Using the define directive

#include<iostream>


using namespace std;


#define PI 3.14 // it was #define PI 3.14;


int main()
{
    double radius = 5.0;
    double circle;


    circle = 2 * PI * radius; //The error is here


    cout << circle;


    cin.get();


    return 0;
}

Any help will be appreciated.

Thanks

**jimblumberg** · 08-30-2016

In a C++ program you really should avoid using macros (#define) whenever possible. In this case use a const qualified variable instead.

Jim

**CNewProg** · 08-30-2016

Originally Posted by jimblumberg

In a C++ program you really should avoid using macros (#define) whenever possible. In this case use a const qualified variable instead.

Jim

Why? and how and where to define const qualified variable? Thanks

**Salem** · 08-30-2016

Something like

const double PI = 3.14159;

**jimblumberg** · 08-31-2016

Why?

The biggest reason is that const qualified variables are type safe and macros are not. In C++ macros are usually considered a bad practice because there are usually other ways of implementing the macro that are safer and easier to understand. Also IMO the compiler error messages involved in malformed macros are usually harder to understand.

and where to define const qualified variable?

In this case you could use the const qualified variable in the same location that you used the define, in the global scope. However unlike the macro you can also use this const defined variable inside your function eliminating the use of the global variable altogether.

Jim

**CNewProg** · 08-31-2016

OK, good to know. Thanks all for the replies.

Thread: What's wrong in this code?

Thread Tools

Search Thread

Display

What's wrong in this code?

Similar Threads

What's wrong with this code!!!

What is wrong with my code?

What's wrong with this code...?

What is wrong with this code??? Can U help??

What is wrong with the code??

Tags for this Thread