while loop

[manaila]

hi,
Can anyone tell me what this loop does, i'm new to C++:

while(a)
{
    //some statements
}

i'm interested in "while(a)", i mean I am used to things like while(a == 1), that is some condition. So what does the while(a) thing do?

cheers

[mailkamlesh]

While(a)
{
}

is infinite loop , provided a has a definate value

[Athar]

Integral values can be implicitly converted to bool. So that's equivalent to while(a!=0)

[manaila]

Thank you for the explanations! Another thing that I forgot is a statement like this:

while ((char *obj = next()))
{
    //some statements;
}

Well, the way I interpreted it was that the condition is always true since char *obj = next() is an assignment, leading to an infinite loop, but the way it was used was like there would be a time when the condition would be false. Any comments!!

cheers.

[Athar]

Well, that is not standard C++ - you can't declare a variable inside an expression like that.
But assuming this code:

char* obj;
while (obj=next())
{
    //some statements;
}

The loop continues as long as obj doesn't equal zero (i.e. as long next() doesn't return zero).
Conversion to bool works for pointers as well.

[manaila]

Hmm....! Thank you very much!