C中变量的对数 [英] logarithm of a variable in C

问题描述

嘿，我的代码有问题：


#include< stdio.h>

#include< math .h>


int main（）{

int x;

x = 10;

printf（"％。2f \ n"，log（x））;

}


当我尝试在GCC中编译它时会显示一条错误消息：

函数`main''：

logarithm.c :( .text + 0x19）：未定义引用`log''


如何修复它？


Thans James

Hey, I have a problem with following code:


#include <stdio.h>
#include <math.h>

int main() {
int x;
x = 10;
printf("%.2f\n", log(x));
}

when I try to compile it in GCC it shows an error message:
In function `main'':
logarithm.c:(.text+0x19): undefined reference to `log''

how can I fix it?

Thans James

推荐答案

它为我编译（使用MinGW），这表明编译器命令行或缺少标准库或库错误的路径存在问题。

It compiles for me (using MinGW) which suggests a problem either with your compiler command line or with missing standard libraries or with the path to the libraries being wrong.

您使用的是C还是C ++？

更改 x 的定义，使其为双倍。


C ++支持三个名为 log 的不同函数。它使用magic来根据参数的类型确定三个中的哪一个使用。如果您正在使用C ++，那么可能通过 int 参数欺骗了魔法，寻找不存在的第四版 log 。

Are you using C or C++?
Change the definition of x so that it is a double.

C++ supports three different functions all named log. It uses magic to determine which of the three to use based on the type of the argument. If you''re using C++ then perhaps passing an int argument fooled the magic into looking for a nonexistent fourth version of log.

C ++会自动将int转换为浮点数，因此我怀疑Banfa是正确的，并且库已被排除在构建之外。

C++ would automatically convert the int to a float so I suspect Banfa is correct and a library has been left out of the build.

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