Whats wrong with my C++ syntax here

while input != 0
    { 
        if input == "r";
        cout << "Please input a floating point value for the height, and then a floating point value for the width, seperated by a comma.开发者_C百科" << endl;
        cin  >> height >> width;
    }

I am trying to write a basic program that takes the dimensions of basic shapes and outputs the area. This is what I am starting with, but I am not sure what is wrong with this syntax. Could someone help?

The condition must be in parentheses. Here's your formatted code:

while (input != 0)
    { 
        if (input == "r")
        {
            cout << "Please input a floating point value for the height, and then a floating point value for the width, seperated by a comma." << endl;
            cin  >> height >> width;
        }
    }

You need to have your conditions surrounded by brackets and if needs to have code to execute if the condition is true its not a function call, so :

while (input != 0)
{ 
    if (input == "r"){
        cout << "Please input a floating point value for the height, and then a floating point value for the width, seperated by a comma." << endl;
        cin  >> height >> width;
    }
}

It also looks like your cin statement is wrong as well but without the rest of the code I don't know.

C++ parser/compiler isn't intelligent enough yet to understand what do you mean when you try to say

if input == "r"
when input != 0    

compiler will get confused and won't be able to semantically understand your program. So you need to put parenthesis as mentioned in above answers.