C++ reverse()
C++算法reverse()
C++算法 reverse()函数用于反转范围[first，last)中元素的顺序。
语法
template <class BidirectionalIterator>
void reverse (BidirectionalIterator first, BidirectionalIterator last);
注意: BidirectionalIterator是一个迭代器，用于在向前和向后方向上访问容器的任何元素。
参数
first: 一个双向迭代器，指向元素所在范围内的第一个元素的位置
last : 正向迭代器，在该元素被反转的范围内，它的位置指向比最后一个元素靠后的位置。
返回值
无
复杂度
复杂度在[first，last)范围内是线性的: 交换元素。
数据竞争
[first，last)范围内的对象被修改。
异常
如果元素被交换或迭代器上的操作抛出异常，则此函数将引发异常。
注意: 无效的参数会导致未定义的行为。
示例1
让我们看一下简单的示例来反转给定的字符串:
#include <algorithm>
#include <iostream>
#include <string>
using namespace std;
int main() {
string str = "Hello Myself Nikita";
cout << "Before Reverse : "<< str << endl;
reverse(str.begin(), str.end());
cout <<"After Reverse : " << str << endl;
return 0;
}
输出:
Before Reverse : Hello Myself Nikita
After Reverse : atikiN flesyM olleH
示例2
让我们看另一个简单的示例来反转数字范围:
#include <vector>
#include <algorithm>
#include <iostream>
using namespace std;
int main( ) {
vector <int> v1;
vector <int>::iterator Iter1;
int i;
for ( i = 0 ; i <= 9 ; i++ )
{
v1.push_back( i );
}
cout << "The original vector v1 is:\n ( " ;
for ( Iter1 = v1.begin( ) ; Iter1 != v1.end( ) ; Iter1++ )
cout << *Iter1 << " ";
cout << ")." << endl;
// Reverse the elements in the vector
reverse (v1.begin( ), v1.end( ) );
cout << "The modified vector v1 with values reversed is:\n ( " ;
for ( Iter1 = v1.begin( ) ; Iter1 != v1.end( ) ; Iter1++ )
cout << *Iter1 << " ";
cout << ")." << endl;
return 0;
}
输出:
The original vector v1 is:
( 0 1 2 3 4 5 6 7 8 9 ).
The modified vector v1 with values reversed is:
( 9 8 7 6 5 4 3 2 1 0 ).
示例3
让我们看另一个简单的示例:
#include<iostream>
#include<algorithm>
#include<vector>
using namespace std;
int main()
{
vector <int> v ;
// Inserting elements in vector
for (int i = 0; i < 8; i++)
v.push_back(i+10);
// Displaying elements of vector
vector <int> :: iterator it;
cout<<"Before: ";
for (it = v.begin(); it != v.end(); it++)
cout << (*it) << " ";
cout << "\n\nReverse only from index 5 to 7 in array:\n";
// Reversing elements from index 5 to index 7
reverse(v.begin() + 5, v.begin() + 8);
for (it = v.begin(); it != v.end(); it++)
cout << (*it) << " ";
// Reversing directly from beginning to end
cout << "\nReverse full array:\n";
int a[] = {4, 5, 6, 7};
reverse(begin(a), end(a));
// Print the array
cout << a[0] << a[1] << a[2] << a[3] << '\n';
return 0;
}
输出:
Before: 10 11 12 13 14 15 16 17
Reverse only from index 5 to 7 in array:
10 11 12 13 14 17 16 15
Reverse full array:
7654
示例4
让我们看另一个简单的示例:
#include <iostream>
#include <algorithm>
#include <vector>
#include <iomanip>
using namespace std;
void print(string a[], int N)
{
for(int i = 0; i < N; i++)
{
cout << (i + 1) << ". " << setw(5)
<< a[i] << " ";
}
cout << endl;
}
int main()
{
string s[] = {"George", "John", "Nik", "Alice", "Bob", "Watson"};
cout << "Original order : ";
print(s, 6);
cout << "\nReversing the order ... " << endl;
reverse(s, s + 6);
cout << "Reversed order : ";
print(s, 6);
}
输出:
Original order : 1. George 2. John 3. Nik 4. Alice 5. Bob 6. Watson
Reversing the order ....
Reversed order : 1. Watson 2. Bob 3. Alice 4. Nik 5. John 6. George
