如何从C或C++中的函数返回多个值？

新程序员通常在寻找从函数返回多个值的方法。不幸的是，C和C++不允许直接这样做。但幸运的是，通过一点巧妙的编程，我们可以轻松实现这一点。

以下是从C中的函数返回多个值的方法：

1. 通过使用指针。
2. 通过使用结构。
3. 通过使用数组。

例子： 考虑一个例子，任务是找到两个不同的数字的越来越小。我们可以编写多个函数。主要的问题是调用多个函数很麻烦，因为我们需要返回多个值，当然，还要输入更多的代码行。

1. 使用指针返回多个值： 将参数与地址一起传递，并使用指针更改其值。这样这些值就变成了原始参数。

   // Modified program using pointers #include <stdio.h> // add is the short name for address void compare( int a, int b, int * add_great, int * add_small) { if (a > b) { // a is stored in the address pointed // by the pointer variable *add_great *add_great = a; *add_small = b; } else { *add_great = b; *add_small = a; } } // Driver code int main() { int great, small, x, y; printf ( "Enter two numbers: " ); scanf ( "%d%d" , &x, &y); // The last two arguments are passed // by giving addresses of memory locations compare(x, y, &great, &small); printf ( "The greater number is %d and the" "smaller number is %d" , great, small); return 0; }

   输出：

   Enter two numbers: 
   5 8
   The greater number is 8 and the smaller number is 5
   

2. 使用结构返回多个值： 因为结构是用户定义的数据类型。其思想是定义一个包含两个整数变量的结构，并将较大和较小的值存储到这些变量中，然后使用该结构的值。

   // Modified program using structures #include <stdio.h> struct greaterSmaller { int greater, smaller; }; typedef struct greaterSmaller Struct; Struct findGreaterSmaller( int a, int b) { Struct s; if (a > b) { s.greater = a; s.smaller = b; } else { s.greater = b; s.smaller = a; } return s; } // Driver code int main() { int x, y; Struct result; printf ( "Enter two numbers: " ); scanf ( "%d%d" , &x, &y); // The last two arguments are passed // by giving addresses of memory locations result = findGreaterSmaller(x, y); printf ( "The greater number is %d and the" "smaller number is %d" , result.greater, result.smaller); return 0; }

   输出：

   Enter two numbers: 
   5 8
   The greater number is 8 and the smaller number is 5
   

3. 使用数组返回多个值（仅当返回的项目类型相同时有效）： 当数组作为参数传递时，它的基址就会传递给函数，所以无论对数组副本做了什么更改，它都会在原始数组中更改。 下面是使用数组返回多个值的程序，即在arr[0]处存储较大的值，在arr[1]处存储较小的值。

   // Modified program using array #include <stdio.h> // Store the greater element at 0th index void findGreaterSmaller( int a, int b, int arr[]) { // Store the greater element at // 0th index of the array if (a > b) { arr[0] = a; arr[1] = b; } else { arr[0] = b; arr[1] = a; } } // Driver code int main() { int x, y; int arr[2]; printf ( "Enter two numbers: " ); scanf ( "%d%d" , &x, &y); findGreaterSmaller(x, y, arr); printf ( "The greater number is %d and the" "smaller number is %d" , arr[0], arr[1]); return 0; }

   输出：

   Enter two numbers: 
   5 8
   The greater number is 8 and the smaller number is 5
   

仅用C++方法

1. 使用引用返回多个值： 我们使用 C++中的引用 存储返回的值。

   // Modified program using References in C++ #include <stdio.h> void compare( int a, int b, int &add_great, int &add_small) { if (a > b) { add_great = a; add_small = b; } else { add_great = b; add_small = a; } } // Driver code int main() { int great, small, x, y; printf ( "Enter two numbers: " ); scanf ( "%d%d" , &x, &y); // The last two arguments are passed // by giving addresses of memory locations compare(x, y, great, small); printf ( "The greater number is %d and the" "smaller number is %d" , great, small); return 0; }

   输出：

   Enter two numbers: 
   5 8
   The greater number is 8 and the smaller number is 5
   

2. 使用类和对象返回多个值： 这个想法与结构类似。我们创建一个包含两个整数变量的类，并将大小值存储到这些变量中，然后使用该结构的值。

   // Modified program using class #include <stdio.h> class GreaterSmaller { public : int greater, smaller; }; GreaterSmaller findGreaterSmaller( int a, int b) { GreaterSmaller s; if (a > b) { s.greater = a; s.smaller = b; } else { s.greater = b; s.smaller = a; } return s; } // Driver code int main() { int x, y; GreaterSmaller result; printf ( "Enter two numbers: " ); scanf ( "%d%d" , &x, &y); // The last two arguments are passed // by giving addresses of memory locations result = findGreaterSmaller(x, y); printf ( "The greater number is %d and the" "smaller number is %d" , result.greater, result.smaller); return 0; }

   输出：

   Enter two numbers: 
   5 8
   The greater number is 8 and the smaller number is 5
   

3. 使用STL元组返回多个值： 这个想法与结构类似。我们创建一个包含两个整数变量的元组并返回该元组，然后在main函数中使用tie函数为函数返回的min和max赋值。

   // Modified program using C++ STL tuple #include<iostream> #include<tuple> using namespace std; tuple < int , int > findGreaterSmaller( int a, int b) { if (a < b) { return make_tuple(a, b); } else { return make_tuple(b, a); } } // Driver code int main() { int x = 5, y= 8; int max, min; tie(min, max) = findGreaterSmaller(x, y); printf ( "The greater number is %d and the " "smaller number is %d" , max, min); return 0; } // This article is contributed by Blinkii

   输出：

   The greater number is 8 and the smaller number is 5