while vs for loop

[vipul mehta]

can u give an example where a for loop cannot replace while loop?

[helios]

THERES NONE

[xabnu]

when in doubt refer up to helios; the reason is

while( expression ){}

is exact equivalent of

for( ; expression ; ){},

which is perfectly legal.

[int main]

Just to make sure I get this straight:

int bla;

for (int i; bla = 1;i++);
{
cin<< i;
};

This would be legal. I mean, after thinking about it, there is no reason why it should not work. But the thought simply never occured to me.

int main

[jsmith]

Syntactically it is correct in non-strict mode (this is because i is not declared where you cin it because you have a stray semicolon after the for()). The loop will never terminate (bla = 1 is an assignment expression that, when converted to bool, will always be true since false == 0 and true == not false). Also, the semicolon at the end of the for() means that what you intended to be the loop body -- the cin << i -- is not actually part of the loop.

But yes, the three expressions inside the for() need not refer to the same variables.

[flyersender]

just another detail...

cin must be used like that:

cin >> i ;

to display on screen, use cout:

cout << i;

[int main]

I'm sorry, I mixed up the veriables.

int bla;

for (int i; bla = 1;i++);
{
cin>> bla;
}

The input should change the expression that controls the for-loop.
int main

[helios]

There's still that semicolon at the end of the for, making it an empty loop.