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C++ Exercises: Exchange the first and last characters in a given string and return the new string

C++ Basic Algorithm: Exercise-7 with Solution

Write a C++ program to exchange the first and last characters in a given string and return the new string.

Sample Solution:

C++ Code :

#include <iostream>
using namespace std;

string test(string str)
        {
            return str.length() > 1
                ? str.substr(str.length() - 1) + str.substr(1, str.length() - 2) + str.substr(0, 1) : str;
        }
        
int main() 
 {
  cout << test("abcd") << endl;  
  cout << test("a") << endl;  
  cout << test("xy") << endl;  
  return 0;    
}

Sample Output:

dbca
a
yx

Pictorial Presentation:

C++ Basic Algorithm Exercises: Exchange the first and last characters in a given string and return the new string.

Flowchart:

Flowchart: Exchange the first and last characters in a given string and return the new string

C++ Code Editor:

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Previous: Write a C++ program to remove the character in a given position of a given string. The given position will be in the range 0..string length -1 inclusive.
Next: Write a C++ program to create a new string which is 4 copies of the 2 front characters of a given string. If the given string length is less than 2 return the original string.

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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