Step by Step solution about How to resolve the algorithm Odd word problem step by step in the C++ programming language

The provided C++ code reads characters from the standard input and prints them in a specific order based on whether the number of characters read so far is even or odd. A detailed explanation of the code:

1. Input/Output Streams:

   • cin is used for reading characters from the standard input.
   • cout is used for printing characters to the standard output.

2. isalpha Function:

   • This function checks if a given character is an alphabetical character (a letter).

3. odd Function:

   • This function is responsible for printing characters in reverse order when the number of characters read so far is odd.
   • It uses a lambda expression prev to store a callback function that reverses the printed characters so far.
   • It reads characters one by one, checking if they are alphabetical.
   • If the character is not alphabetical (e.g., punctuation or whitespace), it calls the prev callback to print the reversed characters and then prints the current character.
   • It returns true if the character is not a period ('.') to continue reading characters; otherwise, it returns false to end the loop.

4. even Function:

   • This function is responsible for printing characters in the order they are read when the number of characters read so far is even.
   • It simply reads characters one by one and prints them without any special processing.
   • It returns true if the character is not a period ('.') to continue reading characters; otherwise, it returns false to end the loop.

5. main Function:

   • The main function is the entry point of the program.
   • It initializes a boolean variable e to false.
   • It enters an infinite loop using a while statement.
   • Inside the loop, it calls either the odd function (if e is false) or the even function (if e is true) to process and print characters.
   • After each call to odd or even, it flips the value of e to switch between odd and even processing.
   • The loop continues until the input character is a period ('.') at which point both odd and even will return false, and the loop will end.

#include <iostream>
#include <cctype>
#include <functional>

using namespace std;

bool odd()
{
  function<void ()> prev = []{};
  while(true) {
    int c = cin.get();
    if (!isalpha(c)) {
      prev();
      cout.put(c);
      return c != '.';
    }
    prev = [=] { cout.put(c); prev();  };
  }
}

bool even() 
{
  while(true) {
    int c;
    cout.put(c = cin.get());
    if (!isalpha(c)) return c != '.';
  }
}


int main()
{
  bool e = false;
  while( e ? odd() : even() ) e = !e;
  return 0;
}