C++ STL中的forward_list :: swap()

forward_list :: swap()是CPP STL中的内置函数，它将第一个给定的forward_list的内容与另一个forward_list交换。

句法：

swap(forward_list first, forward_list second)
               or 
forward_list1.swap(forward_list second)

参数：该函数接受两个指定如下的参数：

• 第一–第一个forward_list
• 第二–第二个forward_list

返回值：该函数不返回任何内容。它交换两个列表。

下面的程序演示了上述函数：

程序1：

// CPP program that demonstrates the
// forward_list::swap() function
// when two parameters is passed
#include 
using namespace std;
  
int main()
{
    // initialising the two forward_list
    forward_list firstlist = { 9, 8, 7, 6 };
  
    forward_list secondlist = { 10, 20, 30 };
  
    // printing elements before the swap operation
    // for firstlist and secondlist
    cout << "Before swap operation firstlist was: ";
    for (auto it = firstlist.begin(); it != firstlist.end(); ++it)
        cout << *it << " ";
  
    cout << "\nBefore swap operation secondlist was: ";
    for (auto it = secondlist.begin(); it != secondlist.end(); ++it)
        cout << *it << " ";
  
    // swap operation on two lists
    swap(firstlist, secondlist);
  
    // printing elements after the swap operation
    // for forward1 and secondlist
    cout << "\n\nAfter swap operation firstlist is: ";
  
    for (auto it = firstlist.begin(); it != firstlist.end(); ++it)
        cout << *it << " ";
    cout << "\nAfter swap operation secondlist is:";
    for (auto it = secondlist.begin(); it != secondlist.end(); ++it)
        cout << *it << " ";
    return 0;
}

输出：

Before swap operation firstlist was: 9 8 7 6 
Before swap operation secondlist was: 10 20 30 

After swap operation firstlist is: 10 20 30 
After swap operation secondlist is:9 8 7 6

程式2：

// CPP program that demonstrates the
// forward_list::swap() function
// when two parameters is passed
#include 
using namespace std;
  
int main()
{
    // initialising the two forward_list
    forward_list firstlist = { 9, 8, 7, 6 };
  
    forward_list secondlist = { 10, 20, 30 };
  
    // printing elements before the swap operation
    // for firstlist and secondlist
    cout << "Before swap operation firstlist was: ";
    for (auto it = firstlist.begin(); it != firstlist.end(); ++it)
        cout << *it << " ";
  
    cout << "\nBefore swap operation secondlist was: ";
    for (auto it = secondlist.begin(); it != secondlist.end(); ++it)
        cout << *it << " ";
  
    // swap operation on two lists
    firstlist.swap(secondlist);
  
    // printing elements after the swap operation
    // for forward1 and secondlist
    cout << "\n\nAfter swap operation firstlist is: ";
  
    for (auto it = firstlist.begin(); it != firstlist.end(); ++it)
        cout << *it << " ";
    cout << "\nAfter swap operation secondlist is:";
    for (auto it = secondlist.begin(); it != secondlist.end(); ++it)
        cout << *it << " ";
    return 0;
}

输出：

Before swap operation firstlist was: 9 8 7 6 
Before swap operation secondlist was: 10 20 30 

After swap operation firstlist is: 10 20 30 
After swap operation secondlist is:9 8 7 6

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