CocoaDev

Does anybody know, by any chance, how to define and implement a General/VarArg method in Objective-C? Thanks!

Exactly the same as you do in C. For those (like me until a few moments ago) who don’t know:

void varArgsCTest(General/NSString *a,…) { General/NSString *currentString; va_list argPtr;

va_start(argPtr, a);
currentString=a;

do
{
    General/NSLog(@"C Test: %@",currentString);
    currentString=va_arg(argPtr,General/NSString *);
} while(currentString!=nil);

va_end(argPtr); }

• (void)varArgsObjCTest:(General/NSString *)a, … { General/NSString *currentString; va_list argPtr;

  va_start(argPtr, a); currentString=a;

  do { General/NSLog(@”Obj-C Test: %@”,currentString); currentString=va_arg(argPtr,General/NSString *); } while(currentString!=nil);

  va_end(argPtr); }

Calling these with:

varArgsCTest(@”1”,@”2”,@”3”,@”4”,nil);

[self varArgsObjCTest:@”1”,@”2”,@”3”,@”4”,nil];

Gives the expected output:

C Test: 1 C Test: 2 C Test: 3 C Test: 4 Obj-C Test: 1 Obj-C Test: 2 Obj-C Test: 3 Obj-C Test: 4

General/SamTaylor

A perhaps preferable model is to use a while() loop:

while(temp = va_arg(argPtr, id)) {
... }

This has the benefit of mirroring common use of General/NSEnumerator fairly nicely.

– General/RobRix

It does, but you have to treat the first item (‘a’ in this case) specially, as it isn’t returned by va_arg.

True, but that’s not necessarily a bad thing; General/NSLog would almost certainly want to, for instance. – General/RobRix

A for loop will sort you out, too, assuming ‘a’ isn’t NULL:

for ( currentString = a; currentString; currentString = va_arg(argPtr, id) ) { … }