重载的“ min（int&amp ;, int&）”的调用不明确 [英] call of overloaded 'min(int&, int&)' is ambiguous

问题描述

我在模板上遇到问题。此代码在vc6下通过，但在g ++下失败。
有人能告诉我原因吗？

I got some problem on template.This code passed under vc6 but failed under g++. Is there anybody could tell me the reason? thanks.

#include<iostream>
using namespace std;

template<class T>
T min(T x, T y) {
    return (x < y ? x : y);
}

int main() {
    int i1 = 23, i2 = 15, i;
    float f1 = 23.04, f2 = 43.2, f;
    double d1 = 0.421342, d2 = 1.24342343, d;
    i = min(i1, i2);
    f = min(f1, f2);
    d = min(d1, d2);
    cout << "The smaller of " << i1 << " and " << i2 << " is " << i << endl;
    cout << "The smaller of " << f1 << " and " << f2 << " is " << f << endl;
    cout << "The smaller of " << d1 << " and " << d2 << " is " << d << endl;
}

/ usr / bin / make- f
nbproject / Makefile-Debug.mk QMAKE =
SUBPROJECTS = .build-conf
/ usr / bin / make -f
nbproject / Makefile-Debug.mk
dist / Debug / GNU-MacOSX / traincpp mkdir
-p build / Debug / GNU-MacOSX rm -f build / Debug / GNU-MacOSX / newmain.od g ++
-c -g- MMD -MP -MF build / Debug / GNU-MacOSX / newmain.od -o
build / Debug / GNU-MacOSX / newmain.o
newmain.cpp newmain.cpp：在函数
中'int main（）'：newmain.cpp：13：错误：
重载的'min（int& ;, int&）'
是模糊的newmain.cpp：5：注意：
候选者是：T min（T，T）[with T =
int]
/usr/include/c++/4.2.1/bits/stl_algobase.h:182：
注意：const _Tp&
std :: min（const _Tp& ;, const _Tp&）[with
_Tp = int] newmain.cpp：14：错误：重载的min（float& ;, float&）的调用是
不明确的newmain.cpp：5：注意：
候选者为：T min（T，T）[T =
float]
/usr/include/c++/4.2.1 /bits/stl_algobase.h:182：
注意：const _Tp&
std :: min（const _Tp& ;, const _Tp&）[with
_Tp = float] newmain.cpp：15：错误：调用了重载的min（double& ;,
double& ）'是模糊的newmain.cpp：5：
注意：候选对象是：T min（T，T）
[T = double]
/usr/include/c++/4.2.1 /bits/stl_algobase.h:182：
注意：const _Tp&
std :: min（const _Tp& ;, const _Tp&）[with
_Tp = double] make [2]： * [build / Debug / GNU-MacOSX / newmain.o]
错误1 make [1]： [.build-conf]
错误2 make：* * [.build-impl]错误
2

"/usr/bin/make" -f nbproject/Makefile-Debug.mk QMAKE= SUBPROJECTS= .build-conf "/usr/bin/make" -f nbproject/Makefile-Debug.mk dist/Debug/GNU-MacOSX/traincpp mkdir -p build/Debug/GNU-MacOSX rm -f build/Debug/GNU-MacOSX/newmain.o.d g++ -c -g -MMD -MP -MF build/Debug/GNU-MacOSX/newmain.o.d -o build/Debug/GNU-MacOSX/newmain.o newmain.cpp newmain.cpp: In function 'int main()': newmain.cpp:13: error: call of overloaded 'min(int&, int&)' is ambiguous newmain.cpp:5: note: candidates are: T min(T, T) [with T = int] /usr/include/c++/4.2.1/bits/stl_algobase.h:182: note: const _Tp& std::min(const _Tp&, const _Tp&) [with _Tp = int] newmain.cpp:14: error: call of overloaded 'min(float&, float&)' is ambiguous newmain.cpp:5: note: candidates are: T min(T, T) [with T = float] /usr/include/c++/4.2.1/bits/stl_algobase.h:182: note: const _Tp& std::min(const _Tp&, const _Tp&) [with _Tp = float] newmain.cpp:15: error: call of overloaded 'min(double&, double&)' is ambiguous newmain.cpp:5: note: candidates are: T min(T, T) [with T = double] /usr/include/c++/4.2.1/bits/stl_algobase.h:182: note: const _Tp& std::min(const _Tp&, const _Tp&) [with _Tp = double] make[2]: * [build/Debug/GNU-MacOSX/newmain.o] Error 1 make[1]: [.build-conf] Error 2 make: ** [.build-impl] Error 2

生成失败（退出值2，总计时间：623分钟）

生成 失败 (退出值 2， 总计时间： 623毫秒)

推荐答案

这是因为您已导入所有 std 名称空间，它是一个不可以。请注意，其他候选者是模板 std :: min 。删除 using名称空间std; 并导入选择符号：

It's because you've imported all of the std namespace, which is a no-no. Note the other candidates are template std::min. Remove the using namespace std; and either import select symbols:

using std::cout;
using std::endl;

或使它们合格：

std::cout << "The smaller of " << i1 << " and " << i2 << " is " << i << std::endl;

这篇关于重载的“ min（int&amp ;, int&）”的调用不明确的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！