if (x) means???

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General C++ Programming
if (x) means???

Jul 31, 2013 at 6:13pm

#include<iostream.h>
int main()
{
int x=0,y=0,z=0;
if (x)
{
x--;
y=x+2;
cout<<x--<<endl;
cout<<y;
}
else cout<<x++;
return 0;
}

what does if(x) mean here?

Jul 31, 2013 at 6:15pm

closed account (Dy7SLyTq)

c style version of bool ie false is < 1 and true > 0

Jul 31, 2013 at 6:20pm

vlad from moscow (6539)

if ( x )

is equivalent to

if ( x != 0 )

Jul 31, 2013 at 8:19pm

htirwin (1208)

Vlad is correct and DTSCode is not correct.

In C and C++, zero is false, and non-zero values are true.

Last edited on Jul 31, 2013 at 8:24pm

Jul 31, 2013 at 9:14pm

closed account (Dy7SLyTq)

actually no im correct. my compiler accepts <= 0 as false

Jul 31, 2013 at 9:28pm

htirwin (1208)

actually no im correct. my compiler accepts <= 0 as false

Then it must not be a C or C++ compiler.

Jul 31, 2013 at 9:29pm

vlad from moscow (6539)

@DTSCode

actually no im correct. my compiler accepts <= 0 as false

I am sure you are wrong.

Jul 31, 2013 at 9:32pm

closed account (Dy7SLyTq)

im sure im right

Jul 31, 2013 at 9:36pm

Zhuge (4664)

Certainty notwithstanding, you are wrong.

Jul 31, 2013 at 9:37pm

vlad from moscow (6539)

@DTSCode

Boy read books on C/C++ for beginners. It will be useful for you.

Last edited on Jul 31, 2013 at 9:38pm

Jul 31, 2013 at 9:41pm

closed account (Dy7SLyTq)

i have. my compiler lets me use negative ints as false. but vlad, you just like to say im wrong so im going to stop talking to you now

Jul 31, 2013 at 9:44pm

Zhuge (4664)

Then, as has been said, your compiler does not conform to the C or C++ standards and I would recommend getting one that does.

Jul 31, 2013 at 9:46pm

vlad from moscow (6539)

@DTSCode

i have. my compiler lets me use negative ints as false. but vlad, you just like to say im wrong so im going to stop talking to you now

No problem.:) I only do not know what you are doing here with your personal compiler and giving others wrong advices because others have no and never will have your compiler.:)

Jul 31, 2013 at 10:36pm

closed account (z05DSL3A)

DTSCode wrote:
actually no im correct. my compiler accepts <= 0 as false

Now there's a lesson to never trust your compiler. Compilers are not always correct or compliant. What compiler is it?

edit: the OPs code is also non-standard.

Last edited on Jul 31, 2013 at 10:43pm

Aug 1, 2013 at 12:11am

naraku9333 (2163)

@DTSCode
See http://en.cppreference.com/w/cpp/language/implicit_cast scroll down to boolean conversions.

Aug 1, 2013 at 6:08am

cire (8284)

le standard wrote:
4.12 Boolean conversions [conv.bool] A prvalue of arithmetic, unscoped enumeration, pointer, or pointer to member type can be converted to a prvalue of type `bool`. A zero value, null pointer value, or null member pointer value is converted to `false;` any other value is converted to `true`. A prvalue of type `std::nullptr_t` can be converted to a prvalue of type `bool`; the resulting value is `false`.

le standard wrote:

4.12 Boolean conversions [conv.bool]

A prvalue of arithmetic, unscoped enumeration, pointer, or pointer to member type can be converted to a prvalue of type bool. A zero value, null pointer value, or null member pointer value is converted to false; any other value is converted to true. A prvalue of type std::nullptr_t can be converted to a prvalue of type bool; the resulting value is false.

Aug 1, 2013 at 8:22am

abhishekm71 (820)

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