If you get into the habit of early returns, you start producing bugs. It also means for messy hard-to-read code.
Code: Show/Hide void Func ()
{ if (!(file = fopen(...))) return; if (!(mem = malloc(...))) return; // <-- bug if (something) { // blah blah return; // <--- bug } if (something else) { // blah blah fclose(file); // <-- wasted code, messy free(mem); return; } // blah blah fclose(file); free(mem); } |
I never use a return in the middle of a function, ever. I would write the above like this...
Code: Show/Hide void Func ()
{ file = 0; mem= 0; if (file = fopen(...)) { if (mem = malloc(...)) { if (something) { // blah blah goto Exit; } if (something else) { // blah blah goto Exit; } // blah blah } } Exit: if (file) fclose(file); if (mem) free(mem); } |
All the cleanup in a single place.
CypherJF - Sun Jul 04, 2004 4:44 pm
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But if you didn't fopen and/or want to allocate memory; more or less if the function pre conditions fail, can't you without issue do a premature return?
ie:
int blah(int x) { if (x == 0) return; return 1/x; }
Jackmn - Sun Jul 04, 2004 5:31 pm
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Better:
return x ? 1/x : 0;
( Probably with a comment stating what it does, since that is a little ugly )
Anonymous - Sun Jul 04, 2004 6:16 pm
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@Cyan~Fire
A goto is a jump and an in most cases an if statement is a subtraction and a conditional jump (ok it's less code, but do you want better readability?).
@50% Packetloss
If you think an early return increases file size because of the stack cleanup, I would imagine a sensible compiler would jump to the end of the subroutine so the cleanup code is shared (may depend on compile flags and the length of the jump).
@Mr Ekted
Why use 'goto Exit' over 'else if'? Should goto be avoided where ever possible (porting to another language could be awkward)?
Cyan~Fire - Sun Jul 04, 2004 6:24 pm
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Alright, I see your point.
And why would you ever want to port a C++ program?
Mr Ekted - Sun Jul 04, 2004 6:24 pm
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If you use early return in functions where they are ok, you will end up coming back later and adding code to break them. It's just a bad habit. Even though I am in favor of people using their own coding styles for their own files, I refuse to allow early returns for any project that I am in charge of.
If-else works only in very simple cases. My example above uses "blah blah" to show were much more code could break if-else possibilities. There are always cases where you have to use goto, or some crazy crap like while loops with special exit conditions (or breaks), which makes the code even more unreadable.
If you write your stuff in C to begin with, then porting to another language is never an issue, since you started with the most sensible one.
Anonymous - Sun Jul 04, 2004 6:50 pm
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I know a couple of bytecode languages that don't support goto, I guess that fits in with 'I am in favor of people using their own coding styles for their own files' as people have preferred languages and target platforms too.
CypherJF - Mon Jul 05, 2004 8:20 am
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Reading the Goto; and return things on MSDN, they said to use break, return, and all other jump statements before using a goto... :/
http://msdn.microsoft.com/library/default.asp?url=/library/en-us/vccelng/htm/statem_19.asp
I think if I read that right...
Jackmn - Mon Jul 05, 2004 8:54 am
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It's far better to use a goto when cleanup needs to be done prior to the return, which is true for almost everything except small utility functions.
Mr Ekted - Mon Jul 05, 2004 2:14 pm
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