C/C++ How do I get main to print out an error from a function?

[firekid123]

I'm having trouble with printing out an error with cerr in the main function when there's an error in another function.


Example:

int main (){
//body
//statements

function (//parameters);
cerr<<"there's a problem"<<endl;
}
int function (//parameters){
if a < b
return -1;
else
return 0;
}

How would I get main to print out the error of the function?

 

[diazona]

If the return value of the function is what indicates that there was an error, you need to check the return value in an if statement.

if (/*error value*/ == function(/*parameters*/)) {
  // ...
}

 

[firekid123]

Thanks, that worked.

 

[AlephZero]

For a more general way where you don't have to remember to check the return value from every function call, find out about exception handling and the throw and catch statements.

 

[LudusRex]

There are a few ways to get main to print out an error from a function. One way is to use the return value of the function to indicate whether an error occurred. For example, in the function provided in the question, you can use the return value of -1 to indicate an error and 0 to indicate no error. Then in the main function, you can check the return value of the function and print out an error message using cerr if the value is -1.

Another way is to use an exception handling mechanism, such as try-catch blocks. This allows you to catch any errors that occur in the function and handle them in the main function. For example, you can use a try block in the main function and catch any exceptions thrown by the function, then print out the error message using cerr in the catch block.

You can also pass a reference to a variable in the main function to the function and modify its value in the function if an error occurs. Then in the main function, you can check the value of the variable and print out an error message using cerr if it indicates an error.

Overall, the best approach will depend on the specific needs and structure of your code. It's important to handle errors in a way that is clear and easily readable for other programmers who may need to work with your code.