declaring a variable in if statement-CodePudding

Please condiser the following snippet

//foo is just a random function which returns error code
if(int err = foo() == 0){
    //err should contain the error code
    ...
}

The problem with that is err contains the result of foo() == 0, and what I want to evalute is int err = foo(); then if(err == 0) but inside the if statement.

I have already tried if((int err = foo()) == 0) and it doesn't work.
Also, I don't want to do int err; if((err = foo) != 0)).

Is this possible ?

CodePudding user response：

For C 17 and onwards you can use if statements with initializers:

if (int err = foo(); err == 0) {
   ...
}