C中关于#include<windows.h>的问题

题目：输入两个整数，输出两者中的大者；要求在主函数中输入两个整数，用一个函数max求出其中的大者，并在主函数中输出此值。
标准答案：
#include<stdio.h>
void main()
{
int max(int x,int y);
int a,b,c;
printf("please input two number:");
scanf("%d,%d",&a,&b);
c=max(a,b);
printf("max is %d\n",c);
}
int max(int x,int y)
{
int z;
if(x>y)
z=x;
else
z=y;
return(z);
}
我为解决在非C界面运行程序时闪退的问题，在#include<stdio.h>后加个#include<windows.h>，并在printf()后加上system("pause");
但是我加上他们后，系统提示我：
Compiling...
d.cpp
C:\Program Files\Microsoft Visual Studio\COMMON\MSDev98\Bin\d.cpp(5) : error C2146: syntax error : missing ')' before identifier 'x'
C:\Program Files\Microsoft Visual Studio\COMMON\MSDev98\Bin\d.cpp(5) : error C2065: 'x' : undeclared identifier
C:\Program Files\Microsoft Visual Studio\COMMON\MSDev98\Bin\d.cpp(5) : error C2146: syntax error : missing ')' before identifier 'y'
C:\Program Files\Microsoft Visual Studio\COMMON\MSDev98\Bin\d.cpp(5) : error C2065: 'y' : undeclared identifier
C:\Program Files\Microsoft Visual Studio\COMMON\MSDev98\Bin\d.cpp(5) : error C2059: syntax error : ')'
C:\Program Files\Microsoft Visual Studio\COMMON\MSDev98\Bin\d.cpp(5) : error C2146: syntax error : missing ')' before identifier 'x'
C:\Program Files\Microsoft Visual Studio\COMMON\MSDev98\Bin\d.cpp(5) : error C2059: syntax error : ')'
C:\Program Files\Microsoft Visual Studio\COMMON\MSDev98\Bin\d.cpp(5) : error C2146: syntax error : missing ')' before identifier 'y'
C:\Program Files\Microsoft Visual Studio\COMMON\MSDev98\Bin\d.cpp(5) : error C2059: syntax error : ')'
C:\Program Files\Microsoft Visual Studio\COMMON\MSDev98\Bin\d.cpp(5) : error C2059: syntax error : ')'
C:\Program Files\Microsoft Visual Studio\COMMON\MSDev98\Bin\d.cpp(13) : error C2199: syntax error : found 'int (' at global scope (was a declaration intended?)
C:\Program Files\Microsoft Visual Studio\COMMON\MSDev98\Bin\d.cpp(13) : error C2062: type 'int' unexpected
C:\Program Files\Microsoft Visual Studio\COMMON\MSDev98\Bin\d.cpp(13) : error C2059: syntax error : ')'
C:\Program Files\Microsoft Visual Studio\COMMON\MSDev98\Bin\d.cpp(13) : error C2143: syntax error : missing ';' before '{'
C:\Program Files\Microsoft Visual Studio\COMMON\MSDev98\Bin\d.cpp(13) : error C2447: missing function header (old-style formal list?)
执行 cl.exe 时出错.
d.obj - 1 error(s), 0 warning(s)

这是为什么啊，求解！！！

---

//因为windows.h里有max函数，冲册旁仔突了，
//所州汪以以下的启闹max全部更名为max11就解决了
#include<stdio.h>
#include<windows.h>
void main()
{
int max11(int x,int y);
int a,b,c;
printf("please input two number:");
scanf("%d,%d",&a,&b);
c=max11(a,b);
printf("max is %d\n",c);
system("pause");

}
int max11(int x,int y)
{
int z;
if(x>y)
z=x;
else
z=y;
return(z);
}

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