为什么我会收到"未定义的引用开方"错误即使我包括math.h中头? [英] Why am I getting "undefined reference to sqrt" error even though I include math.h header?
问题描述
我很新的C和我有这个code:
I'm very new to C and I have this code:
#include <stdio.h>
#include <math.h>
int main(void)
{
double x = 0.5;
double result = sqrt(x);
printf("The square root of %lf is %lf\n", x, result);
return 0;
}
但是,当我编译这个用:
But when I compile this with:
gcc test.c -o test
我得到这样一个错误:
I get an error like this:
/tmp/cc58XvyX.o: In function `main':
test.c:(.text+0x2f): undefined reference to `sqrt'
collect2: ld returned 1 exit status
为什么会出现这种情况?为的sqrt()
不在文件math.h
头文件?我得到 COSH
等三角函数同样的错误。为什么呢?
Why does this happen? Is sqrt()
not in the math.h
header file? I get the same error with cosh
and other trigonometric functions. Why?
推荐答案
数学库必须在构建可执行文件时的链接。如何做到这一点由环境而异,但在的Linux / Unix,只需添加 -lm
来的命令:
The math library must be linked in when building the executable. How to do this varies by environment, but in Linux/Unix, just add -lm
to the command:
gcc test.c -o test -lm
数学库被命名为 libm.so
和 -l </ code>命令选项假定
LIB
preFIX和 .A
或的.so
后缀。
The math library is named libm.so
, and the -l
command option assumes a lib
prefix and .a
or .so
suffix.
这篇关于为什么我会收到&QUOT;未定义的引用开方&QUOT;错误即使我包括math.h中头?的文章就介绍到这了,希望我们推荐的答案对大家有所帮助,也希望大家多多支持IT屋!