Thread: what' value relational operators returned

See, following code

if (a = 5 > 4)
;

we know 5 > 4 is True, but True's value is What? Is that 1 ?

Can't you simply print out the result?

Code:

printf("5 > 4  = %d\n",5 > 4 );

To be fair to the OP, he cannot rely on his compiler's output in this case to know what (if anything) is guaranteed by the standard.

After all:

Code:

#include <stdio.h>
#include <ctype.h>
int main(void)
{
  printf("%d\n", isupper('A'));
}

When run on OpenBSD, this prints out 1. Therefore the is* functions return 1 for true, right? Well no, because when I run this on Linux/glibc, I get 256.

It's true that the relational operators all return 1 for true, but testing on one compiler (or multiple compilers, for that matter) cannot prove that.

C : The type of the result is int and has the values 1 if the specified relationship is true, and 0 if false. C++: The type of the result is bool and has the values true or false.

http://publib.boulder.ibm.com/infoce...e/ref/rele.htm

isspace() and so on are different story. Read the doc.

The values returned are non-zero if the character c falls into the
tested class, and a zero value if not.

MORE

Originally Posted by cas

It's true that the relational operators all return 1 for true, but testing on one compiler (or multiple compilers, for that matter) cannot prove that.

Then ask google!

Originally Posted by Bayint Naung

Can't you simply print out the result?

Code:

printf("5 > 4  = %d\n",5 > 4 );

Of corse, but I want a more detailed explanation.

I know 0 is equivalent True, !0 is False. !0 is what value in relational operators
compared, which is confuse me indeed.

Of corse, but I want a more detailed explanation.

I know !0 is equivalent True, 0 is False. !0 is what value in relational operators
compared, which is confuse me indeed

hehe,