C++重载的时候会优先匹配非模块函数

发现当重载函数足够多的时候,

出现可以符合非模块函数,及模块函数都可匹配的时候,

GCC好像会优先匹配非模块函数.

见下面代码

#include <iostream>
#include <vector>
#include <string>
#include <limits>

using namespace std;


int max(const int n1, const int n2)
{
    return n1 > n2 ? n1 : n2;
}
float max( const float f1, const float f2)
{
    return f1 > f2 ? f1 : f2;
}
string max(const string str1, const  string str2)
{
    return str1 > str2 ? str1 : str2;
}




#if 0
int max(const vector<int>& vec)
{

    return *max_element(vec.begin(), vec.end());
}

float max(const vector<float>& vec)
{
    return *max_element(vec.begin(), vec.end());
}

string max(const vector<string>& vec)
{
    return *max_element(vec.begin(), vec.end());
}

int max(const int* array, int size)
{
    int int_max = numeric_limits<int>::min();
    for(int i = 0; i < size; ++i) {
        int_max = max(int_max, array[i]);
    }
    return int_max;
}

float max(const float* array, int size)
{
    float float_max = numeric_limits<float>::min();
    for(int i = 0; i < size; ++i) {
        float_max = max(float_max, array[i]);
    }
    return float_max;
}

string max(const string* array, int size)
{
    return *max_element(array, array + size);
}
#endif

template <typename T>
T max(const vector<T>& vec) 
{
    cout << "invoke" <<endl;
    return *max_element(vec.begin(), vec.end());
}

template <typename T>
T max(const T* array, int size)
{
    return *max_element(array, array + size);
}


int main(int argc, const char *argv[])
{
    cout << "test overload max" << endl;
    

    int n1 = 3;
    int n2 = 9;

    float f1 = 3.14;
    float f2 = 98.44;

    string str1 = "s1";
    string str2 = "abc";


    cout << "max int (" << n1 << " " << n2 << " )" << max(n1, n2) << endl
        << " max float (" << f1  << " " << f2 << " ) " <<  max(f1, f2) 
        << endl
        << "max string ( " << str1 <<  " " << str2 << " ) " << max(str1, str2)
        << endl;


    int int_array[] = {33,444,5,322,124,55,3436};
    vector<int> int_vec (int_array, int_array + sizeof(int_array)/ sizeof(int));
    cout << " the max number of the int vector is : " << max(int_vec) << endl;


    float f_array[] = {34.24, 4324.43, 9999.43, 556.34};
    vector<float> f_vec (f_array, f_array + sizeof(f_array) / sizeof(float));
    cout << " the max number of the float vector is : " << max(f_vec) << endl;

    string str_array[] = {"boog", "gogod", "zero", "loe", "abcdasdfas",
    "asfdksdljjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjj"};
    vector<string> str_vec (str_array, str_array + sizeof(str_array) / sizeof(string));
    cout << " the max number of the string vector is : " << max(str_vec) << endl;

#if 1
    cout << "the max number of the int array is :" 
        << max( int_array, sizeof(int_array)/ sizeof(int)) <<endl;

    cout << "the max number of the flaot array is :" 
        << max( f_array, sizeof(f_array)/ sizeof(float)) <<endl;

    cout << "the max number of the string array is :" 
        << max( str_array, sizeof(str_array)/ sizeof(str_array[0])) 
        << " sizes = " << sizeof(str_array)/ sizeof(str_array[0])
               << " sizes of str_array " << sizeof(str_array )
               << " sizes of str_array[0] " << sizeof(str_array[0] )
        << endl;
#endif
    return 0;
}

output 

test overload max
max int (3 9 )9
max float (3.14 98.44 ) 98.44
max string ( s1 abc ) s1
invoke
the max number of the int vector is : 3436
invoke
the max number of the float vector is : 9999.43
invoke
the max number of the string vector is : zero
the max number of the int array is :3436
the max number of the flaot array is :9999.43
the max number of the string array is :zero sizes = 6 sizes of str_array 24 sizes of str_array[0] 4

如果把#if 0 打开,,那么就不会出现invoke证明调用的是非模块函数