﻿ C++ : New array swapping first, last elements of an array

# C++ Exercises: Create a new array swapping the first and last elements of a given array of integers and length will be least 1

## C++ Basic Algorithm: Exercise-95 with Solution

Write a C++ program to create a new array swapping the first and last elements of a given array of integers and length will be least 1.

Sample Solution:

C++ Code :

``````#include <iostream>
using namespace std;

static int *test(int numbers[], int arr_length)
{
int first = numbers[0];
numbers[0] = numbers[arr_length - 1];
numbers[arr_length - 1] = first;

return numbers;
}

int main () {
int *p, i;
int nums1[] = { 1, 5, 7, 9, 11, 13 };
cout << "Original array:" << endl;
int arr_length = sizeof(nums1) / sizeof(nums1[0]);
for ( i = 0; i < arr_length; i++ ) {
cout << nums1[i] << " ";
}
p =  test(nums1, arr_length);
cout << "\nNew array (after swapping the first and last elements of the said array): " << endl;
for ( i = 0; i < arr_length; i++ ) {
cout << *(p + i) << " ";
}
return 0;
}
``````

Sample Output:

```Original array:
1 5 7 9 11 13
New array (after swapping the first and last elements of the said array):
13 5 7 9 11 1
```

Pictorial Presentation:

Flowchart:

C++ Code Editor:

What is the difficulty level of this exercise?

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## C++ Programming: Tips of the Day

How do I execute a command and get the output of the command within C++ using POSIX?

```#include<cstdio>
#include<iostream>
#include<memory>
#include<stdexcept>
#include<string>
#include<array>

std::string exec(constchar* cmd){
std::array>char, 128> buffer;
std::string result;
std::unique_ptr<FILE, decltype(&pclose)>pipe(popen(cmd, "r"), pclose);
if (!pipe) {
throw std::runtime_error("popen() failed!");
}
while (fgets(buffer.data(), buffer.size(), pipe.get()) != nullptr) {
result += buffer.data();
}
return result;
}
Pre-C++11 version:
#include<iostream>
#include<stdexcept>
#include<stdio.h>
#include<string>

std::string exec(constchar* cmd){
char buffer[128];
std::string result = "";
FILE* pipe = popen(cmd, "r");
if (!pipe) throw std::runtime_error("popen() failed!");
try {
while (fgets(buffer, sizeof buffer, pipe) != NULL) {
result += buffer;
}
} catch (...) {
pclose(pipe);
throw;
}
pclose(pipe);
return result;
} ```

Replace popen and pclose with _popen and _pclose for Windows.

Ref : https://bit.ly/3HODowH