Question

Please, please help!

(Programming Assignment: fork gymnastics) Write a C/C++ program (call it string-invert) that takes a string argument from the command line and outputs the string in reversed order You have two constraints: Constraint 1: Each process can output at most one character. If you want to output more than a single character, you must fork off one or more processes in order to do that, and each of the forked processes in turn outputs a single character t 2: Each process can fork-off at most one other process. After the call to program string invert with the command line argument, the output should appear, and no more processes should be running, in addition to the shell. Test your program on any UNIX/LINUX machine, and turn in the source code as part of the written assignment. (The source code should be at most a few lines long.)

Answer 1

Program Screenshot:

Sample output 1:

Sample output 2:

Code to copy:

#include<stdio.h>

#include<stdlib.h>

#include<sys/wait.h>

#include<unistd.h>

#include<string.h>

#define SIZE 200

//definition of the main function.

//takes a string argument from the command

//line and outputs the string in reversed order

int main(int argc, char *argv[])

{

     //declare a string variable

     char str[SIZE];

     //declare a pointer

     char *ptr;

     //declare pid_t

     pid_t pid;

     int temp = 0;

     //copy the command line input

     //int the string str.

     strcpy(str, (char*)argv[1]);

     //print the input string

     printf("Input string: %s", str);

     fflush(stdout);

     ptr = str;

     printf("Reverse string: ");

     for (int i = strlen(str) - 1;i >= 0;i--)

     {

           //each process can output at most one character.

           if (pid = fork() == 0)

           {

                //outputs a single character

                printf("%c", ptr[i]);

                break;

           }

           //Each process can fork-off at most one other process

           wait(&temp);

     }

     if (pid == 0)

           printf(" ");

}