I am interested in editing the sqrt function from math.h so that it does not allow negative numbers to be passed to it. I am also interested in how these math functions work in C.
Is there somewhere in the compiler files that has the actual function definition and the code that does all of the computation of the square roots?
Is this actually written in C or in another language?
Well you can get the source code for the GNU libc implementation
http://www.gnu.org/software/libc/
If you have some $$$ compiler, then getting the source code usually involves more $$$.
> Is this actually written in C or in another language?
Mostly C, with minor bits of ASM seems usual.
If you dance barefoot on the broken glass of undefined behaviour, you've got to expect the occasional cut.
If at first you don't succeed, try writing your phone number on the exam paper.
THanks
I am just using Dev C++ because it is easy and free
Don't ever change the standard librairy.Originally Posted by hammer1234
Also, sqrt() already does not allow negitive numbers to be passed to it. It return 0 if you try, and prints an error to stderr.
If that's all you're trying to do, use this:I am interested in editing the sqrt function from math.h so that it does not allow negative numbers to be passed to it.
Then just call sqrt() as usual.Code:#define sqrt(x) (x < 0 ? sqrt(-x) : sqrt(x))
That's what the OP is trying to fix!Also, sqrt() already does not allow negitive numbers to be passed to it. It return 0 if you try, and prints an error to stderr.
dwk
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Using dev c++ sqrt definately doesn't return 0 when negative values are passed. I notived in the gnu lib that i was told to download above that the sqrt function already had checks for negative values.
> Using dev c++ sqrt definately doesn't return 0 when negative values are passed.
Rewriting standard functions to do what you want will only confuse you and other readers later on.
If you want your own mysqrt(), then write that as a short function
Simple, easy. Nobody gets confused and nobody has to faff about with customised libc implementations.Code:double mysqrt ( double x ) { if ( x < 0.0 ) return 0.0; else return sqrt(x); }
If you dance barefoot on the broken glass of undefined behaviour, you've got to expect the occasional cut.
If at first you don't succeed, try writing your phone number on the exam paper.
Thanks God of C. I was really more interested in just seeing how it all worked.
Thanks for your help
