simple program, strange result

[andthen]

Here is the code:

#include <stdio.h>

int main() {
double a = 3.01;
int b = (int)(a * 100.0);
printf("%d",b);
return 0;
}

I believe that the output should be "301", however I am getting output of
"300" when I compile this program on borland's compiler (bcc32) and run it.
I also tried a compiler I got from the internet called lcc, which also leads
to output of "300". I tried Microsoft's compiler and it gave me "301". Does
anyone know what the explanation is for these strange results? Also I do not
have access to gcc right now, but I would be interested to know which output
it gives.

 

[Hans-Christian Egtvedt]

Here is the code:

#include <stdio.h>

int main() {
double a = 3.01;
int b = (int)(a * 100.0);
printf("%d",b);

modified to:
printf("%d\n",b);

return 0;
}

I believe that the output should be "301", however I am getting output of
"300" when I compile this program on borland's compiler (bcc32) and run it.
I also tried a compiler I got from the internet called lcc, which also leads
to output of "300". I tried Microsoft's compiler and it gave me "301". Does
anyone know what the explanation is for these strange results? Also I do not
have access to gcc right now, but I would be interested to know which output
it gives.

Made a quick file called test.c

~ > gcc -Wall -o test test.c
~ > ./test
300

~ > gcc -Wall -O2 -o test test.c
~ > ./test
301

 

[dandelion]

<snip>
Does anyone know what the explanation is for these strange results?

Yes. In fact this question is asked so frequently that the answer is in a
Frequently Asked Questions section.

http://www.eskimo.com/~scs/C-faq/q14.1.html

 

[andthen]

Thanks, that makes sense.

 

[CBFalconer]

Thanks, that makes sense.

No it doesn't. There is nothing for 'that' to refer to.