goto statement

[fixmybug]

Hello Experts,

I am not a programming savvy. I need a help from you guys

can someone help me to understand the negative implications of goto statement. what is bad about it.

any help is greatly appreciated

[PanGalactic]

Google "goto considered harmful".

[firedraco]

Here is an example of how it can be used badly:

int main() {
    int a = 0, b = 0, c = 0;
    cin >> a >> b >> c; //assume error checking etc
start:
    if(a > 6) goto a;
    else if(b < 2) goto b;
    goto 5;
l1:
    goto start;
b:p:
    if(c == 5) goto z;
a:
    if(a < 6 && b > 1) goto aa;
    else goto p;
z:aa:
    goto g;
g:
    cout<<(a+b+c)%5<<endl;
    return 0;
}

[helios]

I believe labels have to be identifiers.

[Duthomhas]

Can of worms.

Here's some more reading for you.
http://www.cplusplus.com/forum/beginner/2287/


[edit] In C and C++, yes, they have to be identifiers. In Pascal, they can be numbers.

[chrisname]

You can also goto pointers (I think that's because in asm, you can jump to addresses (actually, all jumps to identifiers are precomputed to memory addresses IIRC); e.g. jmp 0x1000 (near jump) or jmp 8:0x1000 (far jump)).

Quote from K&R:

Pointers have also been lumped with goto to make impossible to understand programs.

(something like that, anyway).

[helios]

That's a GCC extension.

[Null]

Are you talking about this? http://www.cplusplus.com/forum/general/13637/

[chrisname]

Yes.