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函数。不幸的是，C和C++不允许直接这样做。但是幸运的是，通过一些巧妙的编程，我们可以轻松实现这一目标。

下面是从C函数中返回多个值的方法：

1. 通过使用指针。
2. 通过使用结构。
3. 通过使用数组。

示例：考虑一个示例，其中的任务是查找两个不同数字中的较大和较小值。我们可以编写多个函数。主要问题是调用多个函数的麻烦，因为我们需要返回多个值，并且当然需要键入更多的代码行。

1. 使用指针返回多个值：通过参数传递其地址，并使用指针更改其值。这样就可以将值更改为原始参数。

   // Modified program using pointers
   #include 
     
   // 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: \n");
       scanf("%d%d", &x, &y);
     
       // The last two arguments are passed
       // by giving addresses of memory locations
       compare(x, y, &great, &small);
       printf("\nThe 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：由于结构是用户定义的数据类型。这个想法是用两个整数变量定义一个结构，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 
   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: \n");
       scanf("%d%d", &x, &y);
     
       // The last two arguments are passed
       // by giving addresses of memory locations
       result = findGreaterSmaller(x, y);
       printf("\nThe 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(仅当返回的项目具有相同类型时才有效)：当将数组作为参数传递时，其基地址将传递给函数，因此，对数组副本所做的任何更改都将在原始数组。
   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]中存储较小的值。

   // Modified program using array
   #include 
     
   // 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: \n");
       scanf("%d%d", &x, &y);
     
       findGreaterSmaller(x, y, arr);
     
       printf("\nThe 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C++方法

1. 使用引用返回多个值：我们在C++中使用引用来存储返回的值。

   // Modified program using References in C++
   #include 
     
   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: \n");
       scanf("%d%d", &x, &y);
     
       // The last two arguments are passed
       // by giving addresses of memory locations
       compare(x, y, great, small);
       printf("\nThe 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Class和Object返回多个值：这个想法类似于结构。我们创建一个具有两个整数变量的类，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 class
   #include 
     
   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: \n");
       scanf("%d%d", &x, &y);
     
       // The last two arguments are passed
       // by giving addresses of memory locations
       result = findGreaterSmaller(x, y);
       printf("\nThe 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：这个想法类似于结构。我们使用两个整数变量创建一个元组并返回该元组，然后在main函数内部，我们使用tie函数将值分配给min和max，该值由该函数返回。

   // Modified program using C++ STL tuple
   #include
   #include
     
   using namespace std;
     
   tuple  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
   

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