c standard

[Florian Hengstberger]

Following is possible with gcc and g++:

#include <math.h>

double sin(double)
{
 return 1;
}

int main()
{
 sin(1);
 return 1;
}

Why I don't get any warnings like:

sin prevously defined in math.h ...

when I compile with -Wall -pedantic -ansi.

Why is it possible to overwrite the definition of sin,
is this part of the standard?

Secondly the definition (not declaration) of double sin(double)
misses a variable!
Is this ok, when the variable is not referenced in the code?

Thanks in advance,
Florian

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Linux/BSD: The daemons are not longer just in my head!
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Florian Hengstberger
e0025265 at student.tuwien.ac.at
http://stud3.tuwien.ac.at/~e0025265
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