新人求助QAQ

[wcx998]

#include <stdio.h>
#include<math.h>
#define area(a,b,n) (a*b*sqrt(n))/2
#define s
int main()
{
int N,i=1;
double a,b,c,m,n;
scanf("%d",&N);
while(i<=N)
{
scanf("%lf%lf%lf",&a,&b,&c);
m=(a*a+b*b+c*c)/2*a*b;
n=1-m*m;
printf("%lf",area(a,b,n));
}
return 0;
}
这是代码，也没有错误啊，但是编译的时候会有
duplicate symbol _main in:
/Users/anetinetta/Library/Developer/Xcode/DerivedData/lasr-fwtvgxvysmiglgewhsahmbtjwuim/Build/Intermediates/lasr.build/Debug/lasr.build/Objects-normal/x86_64/main.o
/Users/anetinetta/Library/Developer/Xcode/DerivedData/lasr-fwtvgxvysmiglgewhsahmbtjwuim/Build/Intermediates/lasr.build/Debug/lasr.build/Objects-normal/x86_64/cc.o
ld: 1 duplicate symbol for architecture x86_64
clang: error: linker command failed with exit code 1 (use -v to see invocation)
整个是一长串
Ld /Users/anetinetta/Library/Developer/Xcode/DerivedData/lasr-fwtvgxvysmiglgewhsahmbtjwuim/Build/Products/Debug/lasr normal x86_64
cd "/Users/anetinetta/Library/Mobile Documents/com~apple~CloudDocs/lasr"
export MACOSX_DEPLOYMENT_TARGET=10.11
/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/clang -arch x86_64 -isysroot /Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX10.12.sdk -L/Users/anetinetta/Library/Developer/Xcode/DerivedData/lasr-fwtvgxvysmiglgewhsahmbtjwuim/Build/Products/Debug -F/Users/anetinetta/Library/Developer/Xcode/DerivedData/lasr-fwtvgxvysmiglgewhsahmbtjwuim/Build/Products/Debug -filelist /Users/anetinetta/Library/Developer/Xcode/DerivedData/lasr-fwtvgxvysmiglgewhsahmbtjwuim/Build/Intermediates/lasr.build/Debug/lasr.build/Objects-normal/x86_64/lasr.LinkFileList -mmacosx-version-min=10.11 -Xlinker -object_path_lto -Xlinker /Users/anetinetta/Library/Developer/Xcode/DerivedData/lasr-fwtvgxvysmiglgewhsahmbtjwuim/Build/Intermediates/lasr.build/Debug/lasr.build/Objects-normal/x86_64/lasr_lto.o -Xlinker -export_dynamic -Xlinker -no_deduplicate -fobjc-arc -fobjc-link-runtime -Xlinker -dependency_info -Xlinker /Users/anetinetta/Library/Developer/Xcode/DerivedData/lasr-fwtvgxvysmiglgewhsahmbtjwuim/Build/Intermediates/lasr.build/Debug/lasr.build/Objects-normal/x86_64/lasr_dependency_info.dat -o /Users/anetinetta/Library/Developer/Xcode/DerivedData/lasr-fwtvgxvysmiglgewhsahmbtjwuim/Build/Products/Debug/lasr

duplicate symbol _main in:
/Users/anetinetta/Library/Developer/Xcode/DerivedData/lasr-fwtvgxvysmiglgewhsahmbtjwuim/Build/Intermediates/lasr.build/Debug/lasr.build/Objects-normal/x86_64/main.o
/Users/anetinetta/Library/Developer/Xcode/DerivedData/lasr-fwtvgxvysmiglgewhsahmbtjwuim/Build/Intermediates/lasr.build/Debug/lasr.build/Objects-normal/x86_64/cc.o
ld: 1 duplicate symbol for architecture x86_64
clang: error: linker command failed with exit code 1 (use -v to see invocation)
这些，我有在百度上查过，方法也用了很多种，但是都没有用QAQ，有没有大佬来帮帮我

[ooolinux]

#define area(a,b,n) (a*b*sqrt(n))/2 没有特殊理由，不要定义宏，用函数试试。

[赵4老师]

重新新建console空项目。

[ooolinux]

你这个宏的公式我没去理解，不过a和b都少了括号，因为它们代入的时候可能是一个加法表达式。

[wcx998]

谢谢楼上的各位大佬！ 我按照如上所说，将代码改过后仍然不能编译，但是似乎是头文件的问题。因为如果引用了除<stdio.h>以外的头文件，都会报错 ndefined symbols for architecture x86_64: "_itoa", referenced from: _main in main.o ld: symbol(s) not found for architecture x86_64 clang: error: linker command failed with exit code 1 (use -v to see invocation) 我也把代码发给同学试过了，她在windows下的codeblock是可以正常编译的，但是……但是我不知道如何来解决这个问题。

[Rocker的创意工坊]

没有链接数学库？

[gaozeng851998821]

#define s 宏后面没有定义字符串，你添加上一个字符串试试

[wcx998]

嗯……链接数学库是指#include<math.h>

[wcx998]

哎呀，不小心发出去了…… 链接数学库是指在一开始加上#include<math.h>吗？ 这个我已经加上了。

[wcx998]

谢谢楼上诸位，问题终于被解决啦！