C++ 数组反转

本节将讨论在C++编程语言中反转数组的不同方式。反转数组意味着改变给定数组元素的顺序。该技术将数组的最后一个元素反转为第一个元素，而第一个元素变为最后一个元素。然而，该过程会一直持续，直到数组的所有字符或元素完全反转。

例如，数组包含如下元素：’H’、’E’、’L’、’L’、’O’，当我们反转数组的所有元素时，它返回倒置的数组，即’O’、’L’、’L’、’E’、’H’。因此，通过这种方式，数组中的所有字符都被反转了。

不同的数组翻转方法

以下是在C++编程语言中获取翻转数组的各种方法。

• 使用for循环翻转数组
• 使用reverse()函数翻转数组
• 使用用户定义的函数翻转数组
• 使用指针翻转数组
• 使用递归函数翻转数组

使用for循环翻转数组的程序

让我们创建一个使用for循环翻转数组元素的程序。

Program1.cpp

#include 
using namespace std;

int main ()
{
    int arr[50], num, temp, i, j;
    cout << " Please, enter the total no. you want to enter: ";
    cin >> num;

    // use for loop to enter the numbers 
    for (i = 0; i < num; i++)
    {
        cout << " Enter the element " << i+1 << ": ";
        cin >> arr[i];
    }


    for ( i = 0, j = num - 1; i < num/2; i++, j--)
    {   
        temp = arr[i];
        arr[i] = arr[j];
        arr[j] = temp;
    }
    cout << "\n Reverse all elements of the array: " << endl;
    // use for loop to print the reverse array
    for ( i = 0; i < num; i++)
    {
        cout << arr[i] << " ";
    }
    return 0;
}

输出

Please, enter the total no. you want to enter: 6
 Enter the element 1: 78
 Enter the element 2: 12
 Enter the element 3: 54
 Enter the element 4: 24
 Enter the element 5: 7
 Enter the element 6: 90

 Reverse all elements of the array:
90 7 24 54 12 78

使用reverse ()函数反转数组的程序

让我们通过一个示例来使用C++中的reverse()函数打印一个数组的反转。

Program2.cpp

#include 
#include 
using namespace std;

// declare disp() function 
void disp(int arr1[], int num)
{
    int i;
    // use for loop to iterate the characters
    for ( i = 0; i < num; i++)
    {
        cout << arr1[i] << " ";
    }
}

// define reverse() function to reverse the array elements
void reverse(int arr1[], int num)
{
    reverse(arr1, arr1 + num); 
}

int main ()
{
    // declare and initialize an array
    int arr1[] = {34, 78, 21, 90, 5, 2};
    int num = sizeof(arr1)/sizeof(arr1[0]);

    // call reverse function and pass parameters
    reverse(arr1, num);
    disp(arr1, num); /* call disp() function to print the revrse array. */

    return 0; 
}

输出

2 5 90 21 78 34

使用用户定义的函数来反转数组的程序

让我们来考虑一个使用用户定义的函数在C++中显示数组元素反转的示例。

Program3.cpp

#include 
using namespace std;

void ArrRev ( int [], int);
int main ()
{
    int arr[50], num, i, j, temp;
    cout << " Number of elements to be entered: " << endl;
    cin >> num;

    cout << " Enter the array elements: " << endl;

    // use for loop to enter the elements
    for ( i = 0; i < num; i++)
    {
        cin >> arr[i];
    }
    cout << " Elements are: \n";
    // display entered elements in array
    for ( i = 0; i < num; i++)
    {
        cout << arr[i] << " ";
    }
    ArrRev (arr, num); // call function

    cout << " \n The reverse of the given array is: \n";
    // use for loop to print the reverse array elements
    for ( i = 0; i < num ; i++)
    {
        cout << arr[i] << " ";
    }
    cout << endl;
    return 0;
}

void ArrRev ( int ar[], int a2)
{
    int i, j, temp;
    j = a2 - 1;
    for ( i = 0; i < j; i++, j--)
    {
        temp = ar[i];
        ar[i] = ar[j];
        ar[j] = temp;
    }
}

输出

Number of elements to be entered:
7
 Enter the array elements:
45
32
89
21
78
34
65
 Elements are:
45 32 89 21 78 34 65
 The reverse of the given array is:
65 34 78 21 89 32 45

使用指针反转数组的程序

我们来看一个示例，演示在C++中使用指针反转数组元素。

Program4.cpp

#include 
using namespace std;
int main ()
{
    // declare the size of array
    int arr[50], arr2[50];
    int *ptr, i, num;
    cout <<" No. of array elements to be entered: "<< endl;
    cin >> num; 

    cout <<" Enter the elements: ";
    // use for loop to insert the array elements
    for (i = 0; i < num; i++)
    {
        cin >> arr[i];
    }
    ptr = &arr[0];
cout <<" Entered elements of the array are: \n" <

输出

No. of array elements to be entered:
6
 Enter the elements: 45
32
89
63
4
6
 Entered elements of the array are:

        45      32      89      63      4       6
 The reversed array elements are:

         6
         4
         63
         89
         32
         45

使用递归函数反转数组

让我们创建一个程序，在C++中使用递归函数来反转数组元素。

Program5.cpp

#include 
using namespace std;

// initialize array
int arr[] = { 20, 34, 5, 8, 1, 78};

// size of the array
int size = sizeof( arr) / sizeof (arr[0]);

void reverseArr ( int arr[] , int num)
{
    // check the size of array
    if ( num == size)
        return;

    // extract array elements
    int elem = arr [ num];

    // recursively calls the next element of the array
    reverseArr ( arr, num + 1);
    // assigning elements
    arr [ size - num - 1] = elem;
}

int main ()
{
    int i;
    // call recursive function (start from first elements
    cout << " Original elements of the arrays " << endl;
    for ( int i = 0; i < size; i++)
    {
        cout << arr[i] << " ";
    }

    reverseArr (arr, 0);
    cout << " \n Reverse elements of the array are: " << endl;
    // display the array elements
    for ( int i = 0; i < size; i++)
    {
        cout << arr[i] << " ";
    }
    return 0;
}

输出

Original elements of the arrays
20 34 5 8 1 78
 Reverse elements of the array are:
78 1 8 5 34 20