From: lalawawa <usenet@...>
Date: 2010-01-18T10:00:05+09:00
Subject: basic question: passing a modifiable argument to a routine

Arguments to subroutines seem to be passed by value in ruby

$ irb
irb(main):001:0> def woof(a)
irb(main):002:1>   a += 2
irb(main):003:1> end
=> nil
irb(main):004:0> b = 5
=> 5
irb(main):005:0> woof(b)
=> 7
irb(main):006:0> b
=> 5
irb(main):007:0>

so how do I pass a variable to a routine if I want the routine to
modify the variable.  In C I would say:

void woof(int *a) {
    *a += 2;
}
int b = 5;
woof(&b);
printf("%d\n", b);

would output 7.