Question

I have read a rule somewhere to:

Follow the single-entry/single-exit rule. Never write multiple return statements in the same function.

Is this statement true? If that so, could you please give more detail as to why we should follow this rule?

Answer 1

I’m personally not opposed to early-exit, but I’ll propose a third alternative to SingerOfTheFall for consideration.

Advantages:

• normal code flow (i.e. non-error) flows cleanly through the top of
  the code
• no chance of failing one “something” and passing another
  “something” inadvertently executing a block of code
• you can enforce scope on code blocks; including clean-up on exit of scope for things used in sub-blocks of code

Disadvantage:

• indentations can add up (although this can be mitigated by breaking
  into sub-functions)
• without brace-matching in your editor it can be difficult to match error with failed condition

int foo()
{
    int errorCode = 0;
    if(!something) {
        //100 lines of code
        if(!something) {
            //100 lines of code
            if(!something) {
                //100 lines of code
            }
            else {
                errorCode = -1;
            }
        }
        else {
            errorCode = 11;
       }
    }
    else {
        errorCode = 1;
    }
    return errorCode;
}