What is the value of relational expression

[Sunner Sun]

Hi!

In some compiler, the relational expression's value is 1 for true or 0 for
false. Is this a stardard? Or is there any other compilers which use 0 and
other Non-zero value?

Thank you!
Sunner Sun

[Joona I Palaste]

Sunner Sun <su********@163.com> scribbled the following:

Hi! In some compiler, the relational expression's value is 1 for true or 0 for
false. Is this a stardard? Or is there any other compilers which use 0 and
other Non-zero value?

All comparison operators ==, !=, <, >, <= and >= are guaranteed to
return 1 for true and 0 for false. However, any non-zero value can be
used for true in conditional statements.
For example:
int a = 2==2; /* a is guaranteed to be 1 */
if (2) {
printf("This is guaranteed to be executed\n");
}

--
/-- Joona Palaste (pa*****@cc.helsinki.fi) ------------- Finland --------\
\-- http://www.helsinki.fi/~palaste --------------------- rules! --------/
"Bad things only happen to scoundrels."
- Moominmamma

[Ben Pfaff]

"Sunner Sun" <su********@163.com> writes:

In some compiler, the relational expression's value is 1 for true or 0 for
false. Is this a stardard?
Yes.
Or is there any other compilers which use 0 and other Non-zero
value?

Not C compilers.
--
"This is a wonderful answer.
It's off-topic, it's incorrect, and it doesn't answer the question."
--Richard Heathfield

[Jack Klein]

On Thu, 1 Apr 2004 14:31:01 +0800, "Sunner Sun" <su********@163.com>
wrote in comp.lang.c:

Hi!

In some compiler, the relational expression's value is 1 for true or 0 for
false. Is this a stardard? Or is there any other compilers which use 0 and
other Non-zero value?

Thank you!
Sunner Sun

The C standard specifies that all relational operators produce a value
of 1 for a true condition, and 0 for a false one. That is absolutely
standard, and no C compiler in existence is likely to get this wrong.

That said, the "as-if" rule allows a compiler to skip producing that
value unless it is actually used as a value, as long as it correctly
recognizes the truth or falsehood of the expression.

--
Jack Klein
Home: http://JK-Technology.Com
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[Dan Pop]

In <c4**********@news.yaako.com> "Sunner Sun" <su********@163.com> writes:

In some compiler, the relational expression's value is 1 for true or 0 for
false. Is this a stardard? Or is there any other compilers which use 0 and
other Non-zero value?

How about reading the FAQ *before* posting?

Dan
--
Dan Pop
DESY Zeuthen, RZ group
Email: Da*****@ifh.de