c++函数重载相关问题

Question

用函数重载，实现两个不同类型数据的相加，包括int型，float型，double型，一维和二维数组；编写主函数对重载函数进行测试 （考虑是否可以同时用函数模板）
谢谢！

Answer 1

下面代码需要打开C++17编译选项。

#include <iostream>
#include <iomanip>

template <typename T>
void add(T &a, T b, T c)
{
    a = b + c;
}

template <typename T, int N>
void add(T (&a)[N], const T (&b)[N], const T (&c)[N])
{
    for (int i = 0; i < N; i++)
        a[i] = b[i] + c[i];
}

template <typename T, int M, int N>
void add(T (&a)[M][N], const T (&b)[M][N], const T (&c)[M][N])
{
    for (int i = 0; i < M; i++)
        for (int j = 0; j < N; j++)
            a[i][j] = b[i][j] + c[i][j];
}

template <typename T, int N>
std::enable_if_t<!std::is_same_v<std::remove_cv_t<T>, char>, std::ostream &>
operator<<(std::ostream &os, const T (&a)[N])
{
    os << '[';
    for (int i = 0; i < N; i++)
    {
        os << std::setw(2) << a[i];
        if (i < N - 1)
            os << ' ';
    }
    os << ']';
    return os;
}

template <typename T, int M, int N>
std::enable_if_t<!std::is_same_v<std::remove_cv_t<T>, char>, std::ostream &>
operator<<(std::ostream &os, const T (&a)[M][N])
{
    for (int i = 0; i < M; i++)
    {
        os << '[';
        for (int j = 0; j < N; j++)
        {
            os << std::setw(3) << a[i][j];
            if (i < N - 1)
                os << ' ';
        }
        os << "]\n";
    }
    return os;
}

#define TEST1(type, x, y)                                                                         \
    do                                                                                            \
    {                                                                                             \
        type a, b = x, c = y;                                                                     \
        add(a, b, c);                                                                             \
        std::cout << std::setw(6) << #type << ": " << b << " + " << c << " = " << a << std::endl; \
    } while (0)

#define TEST2(type, N)                                                                            \
    do                                                                                            \
    {                                                                                             \
        type a[N], b[N], c[N];                                                                    \
        for (int i = 0; i < N; i++)                                                               \
        {                                                                                         \
            b[i] = i;                                                                             \
            c[i] = i * 2;                                                                         \
        }                                                                                         \
        add(a, b, c);                                                                             \
        std::cout << std::setw(6) << #type << ": " << b << " + " << c << " = " << a << std::endl; \
    } while (0)

#define TEST3(type, M, N)                           \
    do                                              \
    {                                               \
        type a[M][N], b[M][N], c[M][N], k = 0;      \
        for (int i = 0; i < M; i++)                 \
        {                                           \
            for (int j = 0; j < N; j++)             \
            {                                       \
                b[i][j] = k++;                      \
                c[i][j] = k * 2;                    \
            }                                       \
        }                                           \
        add(a, b, c);                               \
        std::cout << std::setw(6) << #type << ":\n" \
                  << b << "+\n"                     \
                  << c << "=\n"                     \
                  << a << std::endl;                \
    } while (0)

int main()
{
    TEST1(int, 1, 2);
    TEST1(float, 1, 2);
    TEST1(double, 1, 2);
    TEST2(int, 5);
    TEST2(float, 5);
    TEST2(double, 5);
    TEST3(int, 3, 5);
    TEST3(float, 3, 5);
    TEST3(double, 3, 5);
    return 0;
}

$ g++ -Wall -std=c++17 main.cpp
$ ./a.out
   int: 1 + 2 = 3
 float: 1 + 2 = 3
double: 1 + 2 = 3
   int: [ 0  1  2  3  4] + [ 0  2  4  6  8] = [ 0  3  6  9 12]
 float: [ 0  1  2  3  4] + [ 0  2  4  6  8] = [ 0  3  6  9 12]
double: [ 0  1  2  3  4] + [ 0  2  4  6  8] = [ 0  3  6  9 12]
   int:
[  0   1   2   3   4 ]
[  5   6   7   8   9 ]
[ 10  11  12  13  14 ]
+
[  2   4   6   8  10 ]
[ 12  14  16  18  20 ]
[ 22  24  26  28  30 ]
=
[  2   5   8  11  14 ]
[ 17  20  23  26  29 ]
[ 32  35  38  41  44 ]

 float:
[  0   1   2   3   4 ]
[  5   6   7   8   9 ]
[ 10  11  12  13  14 ]
+
[  2   4   6   8  10 ]
[ 12  14  16  18  20 ]
[ 22  24  26  28  30 ]
=
[  2   5   8  11  14 ]
[ 17  20  23  26  29 ]
[ 32  35  38  41  44 ]

double:
[  0   1   2   3   4 ]
[  5   6   7   8   9 ]
[ 10  11  12  13  14 ]
+
[  2   4   6   8  10 ]
[ 12  14  16  18  20 ]
[ 22  24  26  28  30 ]
=
[  2   5   8  11  14 ]
[ 17  20  23  26  29 ]
[ 32  35  38  41  44 ]