﻿ C++ : New array of length 3 from the elements from an array

# C++ Exercises: Create a new array length 3 from a given array the elements from the middle of the array

## C++ Basic Algorithm: Exercise-96 with Solution

Write a C++ program to create a new array length 3 from a given array (length atleast 3) using the elements from the middle of the array.

Sample Solution:

C++ Code :

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

static int* test(int numbers[], int arr_length)
{
static int result[] { numbers[arr_length / 2 - 1], numbers[arr_length / 2], numbers[arr_length / 2 + 1] };
return result;
}

int main()
{
int *result, i;
int nums[] = {1, 5, 7, 9, 11, 13};
int arr_length = sizeof(nums) / sizeof(nums[0]);

cout << "Original array:" << endl;

for ( i = 0; i < arr_length; i++ )
cout << nums[i] << " ";

result = test(nums, arr_length);
cout << "\nNew array:" << endl;
arr_length = sizeof(result) / sizeof(result[0]);
for ( i = 0; i <= arr_length; i++ ) {
cout << *(result + i) << " ";
}

return 0;
}
``````

Sample Output:

```Original array:
1 5 7 9 11 13
New array:
7 9 11
```

Pictorial Presentation:

Flowchart:

C++ Code Editor:

What is the difficulty level of this exercise?

﻿

## 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