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Old 05-30-2013, 09:01 AM   #1
islam_assi
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error (undefined reference to `pow') while compiling a C code in terminal


Hello
I'm trying to compile a C code in terminal ,but I got this error

/tmp/ccoJICUV.o: In function `main':
exo2_main.c.text+0x76): undefined reference to `pow'
collect2: error: ld returned 1 exit status

although I wrote (#include "math.h") in the main
 
Old 05-30-2013, 09:12 AM   #2
jpollard
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It should be in the math library. Add "-lm" to the command used to compile it.
 
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Old 05-30-2013, 09:34 AM   #3
johnsfine
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Quote:
Originally Posted by jpollard View Post
It should be in the math library. Add "-lm" to the command used to compile it.
I agree. The rest of what I have to say only explains that answer. It doesn't replace that answer.

Quote:
Originally Posted by islam_assi View Post
although I wrote (#include "math.h") in the main
Both the declaration and the definition of the function are required.

math.h provides the declaration of the function at compile time in a way that requires the definition to be provided at link time.

The -lm provides access to the definition at link time.

We assume a single gcc command was used to both compile and link, so the -lm could be added to that command. If separate commands were used for compile and link, the -lm belongs on the link command.

Last edited by johnsfine; 05-30-2013 at 09:37 AM.
 
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Old 05-30-2013, 09:38 AM   #4
islam_assi
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how can I add (-lm) to the command ??
the command which I used to compile is (gcc -o exo2 exo2.c exo2_main.c)

Last edited by islam_assi; 05-30-2013 at 09:41 AM.
 
Old 05-30-2013, 09:40 AM   #5
jpollard
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What part of "add it to the command" did you miss? gcc -o exo2 exo2.c exo2_main.c -lm
 
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Old 05-30-2013, 09:43 AM   #6
islam_assi
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the problem solved ,,,, thank you guys
 
  


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