Re: "x ? y : z" notation

[Old_Gray_Bear]

It's called the 'conditional' or 'ternary' operator.

<condition> ? <do if condition was true> : <do if it wasn't>

An example:

$x == 1 ? print "x was '1'" : print "x was something else";

[davido]

$x == 1 ? print "x was '1'" : print "x was something else";

While that's technically correct it doesn't take advantage of the fact that the ternary operator has a return value; whatever expression is evaluate after the ?.

See another adaptation that takes advantage of this feature.

print( "x was " . $x == 1 ? "'1'" : "someting else" );

[rovf]

take advantage of the fact that the ternary operator has a return value

How true; Perl is a bit unorthogonal in this respect, in that there is (at least) one case where you can achieve this effect with a plain 'if':

sub lessthan {
  if($_[0] < $_[1]) {1} else {0}
}

Some languages (old examples: Algol60 and Algol68) are more regular in this respect...

BTW, does someone know by chance which was the first language which used ?: to represent "ternary if"? Of course you had this already in LISP or BCPL, but with a different syntax. The earliest occurance of ?: I know of, is in C, but I wouldn't be surprised if it was used in even older languages already.

[poolpi]

Answer seems to be C


Wikipedia says BCPL (1966 different syntax).


Update:
Ternary_operation ( 1958, ALGOL different syntax too)


hth,
PooLpi

[apok]

Thanks for the explanation! I thought it might be something like that.