[Tutor] Re: Why x+=y instead of x=x+y?

[lumbricus@gmx.net]

> > | It comes from C which was initially implemented on a 
> > | computer which had a different set of assembler instructions 
> > | for generic addition and 'self addition' )
> > 
> > I think it is also related to the complexity of the compiler.  I
> > expect that any modern compiler will turn "x+=1" into INC X.  
> 
> If optimisation is turned off I sincerely hope it doesn't!

Why not?

$ gcc --version
egcs-2.91.66
$ uname
Linux
$ cat inc.c
#include <stdio.h>
int main (void) {
        int i=0;
        i++;
        i+=1;
        i=i+1;
        return 0;
}

$ cc -S inc.c
$ cat inc.s
	[ snip ]
        incl -4(%ebp)
        incl -4(%ebp)
        incl -4(%ebp)
	[ snip ]
$ 

HAND and Greetings, J"o!

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