C++ 使用元组和对从函数返回多个值

我们可能遇到过这样的情况，在工作中，我们的函数可能只有一个部分的返回类型是单一的数据类型，但我们需要返回多个数据类型。为了解决这个问题，我们正在学习使用元组和对来从函数中返回不同的值的概念。

C++中的元组和对

它是一个保存任何数据类型的单元或元素的对象。在C++编程语言中，元组数据类型类std::tuple的大小是固定的。C++中的对是

演示元组的C++代码

// Here, we are writing down the C++ programming language code to 
// demonstrate the concept of std::tuple, std::pair 

#include<iostream>
#include<tuple> 
using namespace std;
int main()
{
    // this below code snippet helps us with declaring the Tuple names jtp
    tuple <char, int, float> jtp;


// the C++ built-in function make tiple helps us with assigning the values
// to the Tuple jtp, which we have just made
    jtp = make_tuple('z', 20, 85.5);

// the below code snippets help us with printing the values of the tuple
// at the initial stage using the get() built-in function
    cout << "values of the Tuple during the initial stage are as follows: ";
    cout << get<0>(jtp) << " " << get<1>(jtp);
    cout << " " << get<2>(jtp) << endl;

// the below code snippets help us with changing the values of the tuple
// at the initial stage using the get() built-in function
    get<0>(jtp) = 'b';
    get<2>(jtp) = 20.5;

// The below code snippet helps us with printing down modified tuple values
// values of the Tuple after the modification stage are as follows: 
cout << "values of the Tuple after the modification stage are as follows: ";
    cout << get<0>(jtp) << " " << get<1>(jtp);
    cout << " " << get<2>(jtp) << endl;

    return 0;
}

输出：

values of the Tuple during the initial stage are as follows: z 20 85.5
values of the Tuple after the modification stage are as follows: b 20 20.5

C++代码演示对

// Here, we are writing down the C++ programming language code to 
// demonstrate the concept of std::pair , tie() in Pair 
#include 
using namespace std;

// the below code snippet implements the driver Code functionality for a tie()
int main()
{
// the below code snippet helps us with declaring the pair 
    pair pair_1 = { 41, 62 };
    int a, b;
    tie(a, b) = pair_1;
    cout << a << " " << b << "\n";

    pair pair_2 = { 63, 84 };
    tie(a, ignore) = pair_2;

// the below code snippet helps us with printing the previous value of b
    cout << a << " " << b << "\n";


// the below code snippet helps us illustrate the pair of multiple pair
    pair > pair_3 = { 103, { 44, 'n' } };
    int x, y;
    char z;



//if we write code as tie(x,y,z) = pair3, we can expect an compilation error
//if we write code as tie(x, tie(y,z)) = pair3, we can expect an compilation
//error, and we need to note the point that all the unique pairs have to be 
// handled with care and explicitly as well.

    x = pair_3.first;
    tie(y, z) = pair_3.second;
    cout << x << " " << y << " " << z << "\n";
}

输出：

41 62
63 62
103 44 n

使用元组和对返回多个值的C++代码

// Here, we are writing down the C++ programming language code to demonstrate
// the concept of std::tuple, std::pair 
//Returning multiple values from a function using Tuple and Pair in C++
#include
using namespace std;

// A Method that returns multiple values using
// tuple in C++.
// Below, we are writing down the code snippet which returns multiple values
// a method using the  concept of Tuples in C++
tuple foo_boo(int n1, int n2)
{
    //This code snippet below returns the tuples after packing them up!
    return make_tuple(n2, n1, 'a');         
}

// // this below code snippet returns us a pair of values with the help of 
// a pair in general.
std::pair foo1(int num1, int num2)
{
    // Packing two values to return a pair
    //the below code snippet returns us the two values after packing them 
    return std::make_pair(num2, num1);          
}

int main()
{
    int a,b;
    char cc;

    // unpacking the values by foo_boo after returning
    tie(a, b, cc) = foo_boo(15, 110);   

    // the below code snippet returns us the values in the pair
    pair p = foo1(25,32);

    cout << "The values returned by the Tuple are as follows: ";
    cout << a << " " << b << " " << cc << endl;

    cout << "The values returned by the Pair are as follows: ";
    cout << p.first << " " << p.second;
    return 0;
}

输出:

The values returned by the Tuple are as follows: 110 15 a
The values returned by the Pair are as follows: 32 25