Re: Problem compiling simple C program
- From: "Joost Witteveen" <joosteto@xxxxxxxxx>
- Date: Wed, 16 Apr 2008 16:54:49 +0200
On 16/04/2008, John Salmon <salmonjj@xxxxxxxxxxx> wrote:
Sven Joachim <svenjoac@xxxxxx> wrote in news:aiYRm-2Tc-23@xxxxxxxxxxxxxxxx:
> On 2008-04-15 20:39 +0200, John Salmon wrote:
>
>> I'm running Debian Etch on a PC. When I try to compile the following
>> (called test.c);
>>
>> #include <math.h>
>> #include <stdio.h>
>>
>> int main()
>> {
>> double
>> val = 1.55;
>>
>> printf("sine: %g\n", sin(val));
>>
>> return 0;
>> }
>>
>> using the command line
>>
>> gcc -Wall -o test test.c
>>
>> I get
>>
>> /tmp/cciDV02m.o: In function `main':
>> test.c:(.text+0x21): undefined reference to `sin'
>> collect2: ld returned 1 exit status
>
> You need to link to the math library by specifying -lm _at the end_ of
> the gcc command line, otherwise the linker does not know about the sin()
> function.
>
>> When I compile the equivalent C++ program using the apropriate C++
>> parameters, everything goes great. Have I neglected to load a Debian
>> package? Any help will be appreciated.
>
> That is to be expected, because C++ programs are automatically linked
> against the math library. In C you have to tell the linker to use it
> with -lm.
>
> Sven
>
>
That solved the linking problem. Now, after a successful compilation, when
I run 'test' I gen no output. ???
"test" is a bash-builtin, and is a executable in /usr/bin/test, so
that is what you were running.
You can run your "test" command by typing
./test
or rename it to something else.
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