#include<iostream>
using namespace std;

template<class numtype>
class Compare
{
public:
    Compare(numtype,numtype);
    numtype min();
    numtype max();
private:
    numtype a;
    numtype b;
};

Compare::Compare(numtype a1,numtype b1):a(a1),b(b1){};

numtype Compare::max()
{
    return a>b?a:b;
}

numtype Compare::min()
{
    return a<b?a:b;
}

int main()
{
    Compare<int> cmp(3,5);
    cout<<"max="<<cmp.max()<<endl;
    Compare<float> cmp1(6.6,8.8);
    cout<<"min="<<cmp1.min()<<endl;
}

//这个程序错在哪儿！ 求大神修改~

一下是编译信息：

Compiling...
Cpp1.cpp
C:\Users\123\Desktop\practice 5\Cpp1.cpp(16) : error C2955: 'Compare' : use of class template requires template argument list
        C:\Users\123\Desktop\practice 5\Cpp1.cpp(14) : see declaration of 'Compare'
C:\Users\123\Desktop\practice 5\Cpp1.cpp(16) : error C2955: 'Compare' : use of class template requires template argument list
        C:\Users\123\Desktop\practice 5\Cpp1.cpp(14) : see declaration of 'Compare'
C:\Users\123\Desktop\practice 5\Cpp1.cpp(16) : error C2065: 'numtype' : undeclared identifier
C:\Users\123\Desktop\practice 5\Cpp1.cpp(16) : error C2146: syntax error : missing ')' before identifier 'a1'
C:\Users\123\Desktop\practice 5\Cpp1.cpp(16) : error C2350: 'Compare::Compare<numtype>::Compare<numtype>' is not a static member
C:\Users\123\Desktop\practice 5\Cpp1.cpp(16) : error C2059: syntax error : ')'
C:\Users\123\Desktop\practice 5\Cpp1.cpp(16) : error C2065: 'a1' : undeclared identifier
C:\Users\123\Desktop\practice 5\Cpp1.cpp(16) : error C2501: 'a' : missing storage-class or type specifiers
C:\Users\123\Desktop\practice 5\Cpp1.cpp(16) : error C2065: 'b1' : undeclared identifier
C:\Users\123\Desktop\practice 5\Cpp1.cpp(16) : error C2448: '<Unknown>' : function-style initializer appears to be a function definition
C:\Users\123\Desktop\practice 5\Cpp1.cpp(18) : error C2955: 'Compare' : use of class template requires template argument list
        C:\Users\123\Desktop\practice 5\Cpp1.cpp(14) : see declaration of 'Compare'
C:\Users\123\Desktop\practice 5\Cpp1.cpp(18) : error C2955: 'Compare' : use of class template requires template argument list
        C:\Users\123\Desktop\practice 5\Cpp1.cpp(14) : see declaration of 'Compare'
C:\Users\123\Desktop\practice 5\Cpp1.cpp(18) : error C2143: syntax error : missing ';' before 'tag::id'
C:\Users\123\Desktop\practice 5\Cpp1.cpp(18) : error C2501: 'numtype' : missing storage-class or type specifiers
C:\Users\123\Desktop\practice 5\Cpp1.cpp(18) : fatal error C1004: unexpected end of file found
执行 cl.exe 时出错.

Cpp1.obj - 1 error(s), 0 warning(s)

下面函数定义也要加上模板，就是你类定义上面的那一行

去C++问吧