问题
Reading the documentation for math.h, it seems like all I should have to do is include math.h, and use the math functions included, such as sqrt. The problem is I get the following error when trying to use sqrt in my program. I tried math.sqrt, but that did not work, either. Any idea what I am doing wrong?
undefined reference to `sqrt'
...
#include <stdio.h>
#include <math.h>
int main (int argc, char *argv[])
{
int a, b;
a = 1;
b = 5;
if (a < sqrt (b))
printf("1 < sqrt(5)");
return 0;
}
回答1:
You need to explicitely link with the math library as sqrt depends on it. Retry with appending -lm to your compilation line :
gcc you_file.c -o my_sqrt -lm
来源：https://stackoverflow.com/questions/16576920/using-math-h-sqrt-function-in-c