STL中的转发列表实现单链接列表。从C++ 11引入的前向列表在插入,删除和移动操作(如排序)方面比其他容器有用,并且允许时间常数插入和删除元素。它与列表的不同之处在于前向列表会跟踪对象的位置仅list的下一个元素同时跟踪下一个和上一个元素。
forward_list::push_front
push_front()函数用于将元素从前面推入转发列表。在当前第一个元素和容器大小增加1之前,新值将从开头插入到“转发”列表中。
用法:
forwardlistname.push_front(value) 参数: The value to be added in the front is passed as the parameter Result: Adds the value mentioned as the parameter to the front of the forward list named as forwardlistname
例子:
Input:forward_list forwardlist{1, 2, 3, 4, 5}; forwardlist.push_front(6); Output:6, 1, 2, 3, 4, 5 Input:forward_list forwardlist{5, 4, 3, 2, 1}; forwardlist.push_front(6); Output:6, 5, 4, 3, 2, 1
错误和异常
1.强大的异常保证-如果引发异常,则容器中没有任何更改。
2.如果转发列表不支持作为参数传递的值,则它将显示未定义的行为。
// CPP program to illustrate
// push_front() function
#include <forward_list>
#include <iostream>
using namespace std;
int main()
{
forward_list<int> myforwardlist{ 1, 2, 3, 4, 5 };
myforwardlist.push_front(6);
// Forward list becomes 6, 1, 2, 3, 4, 5
for (auto it = myforwardlist.begin(); it != myforwardlist.end(); ++it)
cout << ' ' << *it;
}
输出:
6 1 2 3 4 5
应用:使用push_front()函数输入具有以下编号和顺序的空的转发列表,并对给定的转发列表进行排序。
Input: 7, 89, 45, 6, 24, 58, 43 Output:6, 7, 24, 43, 45, 58, 89
// CPP program to illustrate
// application Of push_front() function
#include <forward_list>
#include <iostream>
using namespace std;
int main()
{
forward_list<int> myforwardlist{};
myforwardlist.push_front(43);
myforwardlist.push_front(58);
myforwardlist.push_front(24);
myforwardlist.push_front(6);
myforwardlist.push_front(45);
myforwardlist.push_front(89);
myforwardlist.push_front(7);
// Forward list becomes 7, 89, 45, 6, 24, 58, 43
// Sorting function
myforwardlist.sort();
for (auto it = myforwardlist.begin(); it != myforwardlist.end(); ++it)
cout << ' ' << *it;
}
输出量
6 7 24 43 45 58 89
forward_list::pop_front
pop_front()函数用于从正面弹出列表中删除元素。该值将从一开始就从列表中删除,并且容器大小减小1。
用法:
forwardlistname.pop_front() 参数: No parameter is passed as the parameter. Result: Removes the value present at the front of the given forward list named as forwardlistname
例子:
Input:forward_list forwardlist{1, 2, 3, 4, 5}; forwardlist.pop_front(); Output:2, 3, 4, 5 Input:forward_list forwardlist{5, 4, 3, 2, 1}; forwardlist.pop_front(); Output:4, 3, 2, 1
错误和异常
1. No-Throw-Guarantee-如果引发异常,则容器中没有任何更改。
2.如果列表为空,则显示未定义的行为。
// CPP program to illustrate
// pop_front() function
#include <forward_list>
#include <iostream>
using namespace std;
int main()
{
forward_list<int> myforwardlist{ 1, 2, 3, 4, 5 };
myforwardlist.pop_front();
// forward list becomes 2, 3, 4, 5
for (auto it = myforwardlist.begin(); it != myforwardlist.end(); ++it)
cout << ' ' << *it;
}
输出:
2 3 4 5
应用程序:使用push_front()函数输入具有以下编号和顺序的空前向列表,并打印列表的反面。
Input:1, 2, 3, 4, 5, 6, 7, 8 Output:8, 7, 6, 5, 4, 3, 2, 1
// CPP program to illustrate
// application Of pop_front() function
#include <forward_list>
#include <iostream>
using namespace std;
int main()
{
forward_list<int> myforwardlist{}, newforwardlist{};
myforwardlist.push_front(8);
myforwardlist.push_front(7);
myforwardlist.push_front(6);
myforwardlist.push_front(5);
myforwardlist.push_front(4);
myforwardlist.push_front(3);
myforwardlist.push_front(2);
myforwardlist.push_front(1);
// Forward list becomes 1, 2, 3, 4, 5, 6, 7, 8
while (!myforwardlist.empty()) {
newforwardlist.push_front(myforwardlist.front());
myforwardlist.pop_front();
}
for (auto it = newforwardlist.begin(); it != newforwardlist.end(); ++it)
cout << ' ' << *it;
}
输出量
8 7 6 5 4 3 2 1
相关用法
注:本文由纯净天空筛选整理自AyushSaxena大神的英文原创作品 forward_list::push_front() and forward_list::pop_front() in C++ STL。非经特殊声明,原始代码版权归原作者所有,本译文未经允许或授权,请勿转载或复制。