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Write a program to reverse an array or string in C++
Here, we are given an array or a string of characters. We will create a program to reverse the elements of an array or string.
Let’s take an example to understand the problem,
Input
array = {2, 5, 7, 1, 9}Output
{9, 1, 7, 5, 2}Input
string = “Hello!”
Output
!0lleH
To create a program, we will loop through the elements of the array/string(both work in the same way). Taking one variable for start and one of end. And swap both elements. Increment the start variable and decrement the end variable. The swapping will continue till start variable’s value is less than end variable.
The program can be created in two ways, one is iterative and the other is recursive. We will create program that will demonstrate the working of both methods.
Example
Method 1: Iterative approach
Program :
#include <iostream>
using namespace std;
void revereseArrayIt(int arr[], int start, int end){
while (start < end){
int temp = arr[start];
arr[start] = arr[end];
arr[end] = temp;
start++;
end--;
}
}
int main() {
int arr[] = {6, 9, 1, 4, 0, 5};
int n = sizeof(arr) / sizeof(arr[0]);
cout<<"Orignal Array : ";
for (int i = 0; i < n; i++)
cout<<arr[i]<<" ";
cout<<endl;
revereseArrayIt(arr, 0, n-1);
cout << "Reversed array : ";
for (int i = 0; i < n; i++)
cout<<arr[i]<<" ";
cout<<endl;
return 0;
}
Output
Orignal Array : 6 9 1 4 0 5 Reversed array : 5 0 4 1 9 6
Example
Method 2 : Recursive Approach
#include <iostream>
using namespace std;
void revereseArrayRec(int arr[], int start, int end){
if(start >= end)
return;
int temp = arr[start];
arr[start] = arr[end];
arr[end] = temp;
revereseArrayRec(arr,start+1, end-1);
}
int main() {
int arr[] = {6, 9, 1, 4, 0, 5};
int n = sizeof(arr) / sizeof(arr[0]);
cout<<"Orignal Array : ";
for (int i = 0; i < n; i++)
cout<<arr[i]<<" ";
cout<<endl;
revereseArrayRec(arr, 0, n-1);
cout << "Reversed array : ";
for (int i = 0; i < n; i++)
cout<<arr[i]<<" ";
cout<<endl;
return 0;
}Output
Orignal Array : 6 9 1 4 0 5 Reversed array : 5 0 4 1 9 6
Updated on: 20-Apr-2020
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