Write A C program called Reverse where it will read from an inputfile in .txt fo

Question

Write A C program called Reverse where it will read from an inputfile in .txt form and write an output file in .txt form

The output file will contain the reversed word order of the input file.

The input file words are separated by one or more spaces ' ' or by horizontal tab ' '

The output file words should be separated by one space.

The input and output files, each line ends with new line character (‘ ’). Lines do not exceed 255 characters including new line character.

An example is shown below

Reverse input output

Input File

Output File

Beside an assault scenario.

When will a friendly cube?

The            precedent.

This percent abides without an arm.

The recipe           multiplies.

The provoking football.

scenario. assault an Beside

cube? friendly a will When

precedent. The

arm. an without abides percent This

multiplies. recipe The

football. provoking The

Input File

Output File

Beside an assault scenario.

When will a friendly cube?

The            precedent.

This percent abides without an arm.

The recipe           multiplies.

The provoking football.

scenario. assault an Beside

cube? friendly a will When

precedent. The

arm. an without abides percent This

multiplies. recipe The

football. provoking The

Explanation / Answer

create an input file input.txt and an output file output.txt(output file optional). Save the main file as main.c, compile in gcc and run. Give the below execution command and compilation command

Compilation command: gcc main.c

Execution command: ./a.out input

Open the output.txt file, you will get words in reverse order.

/**********************************/input.txt

Beside an assault scenario.
When will a friendly cube?
The            precedent.
This percent abides without an arm.
The recipe           multiplies.
The provoking football.

/***************************/

/*
============================================================================
Name        : FileOp.c
Author      :
Version     :
Copyright   : Your copyright notice
Description : Hello World in C, Ansi-style
============================================================================
*/

#include <stdio.h>
#include <stdlib.h>
#include <string.h>

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

   //open input file
   char str[20]={0};
   strcpy(str,argv[1]);
   strcat(str,".txt");
   FILE *ip=fopen(str,"r");

   if(ip==NULL)
   {
       printf("Input file does not exist ");
   exit(-1);
   }
   //open or create output file
   FILE *op;
   if(argv[2]!=NULL) //checking if output file exist
   {
   strcpy(str,argv[2]);
   strcat(str,".txt");
   op=fopen(str,"w");
   }
   else
   {
       op=fopen("output.txt","w");
   }

   char buffer[255]={0};
   while(fgets(buffer,sizeof(buffer),ip)) //read till end of input file
   {
       char wstr[255]={0};
       char str[255]={0};
       char *ptr=strtok(buffer," "); //tokenise read string
       while(ptr)
       {
           strcpy(str,ptr); //copy the tocken content in temporary buffer
           strcat(str," "); //pad space
           strcat(str,wstr); //concatenate the previous buffer
           strcpy(wstr,str); //update the whole buffer
           ptr=strtok(NULL," ");
       }
       strcat(wstr," ");
       fprintf(op,"%s",wstr); //print to output file

   }

   printf("Finished ");
   fclose(ip); //close ip file
   fclose(op); //close output file
   return EXIT_SUCCESS;
}

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