Question

IN C LANGUAGE

16.15 Lab 5: filter

Name this program filter.c.

• The program takes two command line arguments: the name of an input file and the name of an output file. The program should confirm the input and output files can be opened. If a file cannot be opened, print the error message Cannot open file '<filename>' where <filename> is the name of the file and return.
  • fopen() will return 0 if it fails to open a file.
• Then, the program will read the file string by string (up to 50 characters in length). If the string consists of only uppercase and lowercase characters, print it.
  • You can use isalpha(char) declared in ctype.h to check whether a character is a-z or A-Z.
  • continue and break might be useful.
• Don't forget to close your files!

Examples

./a.out example.txt output.txt

example.txt	output.txt
The Quick Brown Fox Jumps over the Lazy Old Dog. ALABAMA? Roll Tide!!! P2P 1831 (UA)	The Quick Brown Fox Jumps over the Lazy Old Roll

./a.out does_not_exist.txt output.txt
Cannot open file 'does_not_exist.txt'

Answer 1

#include <stdio.h>
#include <stdlib.h> // For exit()
#include <ctype.h>

int main(int argc,char* argv[])
{
   FILE *inputfptr, *ouputfptr;
   char c;

   // Open one file for reading
   inputfptr = fopen(argv[1], "r");
   if (inputfptr == NULL)
   {
       printf("Cannot open file %s \n", argv[1]);
       exit(0);
   }

   // Open another file for writing
   ouputfptr = fopen(argv[2], "w");
   if (ouputfptr == NULL)
   {
       printf("Cannot open file %s \n", argv[2]);
       exit(0);
   }

   // Read contents from file
   c = fgetc(inputfptr);
   int k = 0;
   while (c != EOF)
   {
   char temp[50];
   if(c!=' ')
   {
   temp[k++] = c;
   }
   else
   {
   int t = 1;
   for(int m=0;m<k;m++)
   {
   if(isalpha(temp[m])){}
   else{t=0;break;}
   }
   if(t==1)
   {
   for(int m=0;m<k;m++)
   {
       fputc(temp[m], ouputfptr);
   }
   fputc(' ', ouputfptr);
   }
   k=0;
   }
       c = fgetc(inputfptr);
   }

   printf("\nContents copied to %s", argv[2]);

   fclose(inputfptr);
   fclose(ouputfptr);
   return 0;
}

/////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////

THE SAME PROGRAMME WITHOUT COMMAND LINE ARGUMENTS

#include <stdio.h>
#include <stdlib.h> // For exit()
#include <ctype.h>

int main(int argc,char* argv[])
{
   FILE *inputfptr, *ouputfptr;
   char c;

   // Open one file for reading
   inputfptr = fopen("example.txt", "r");
   if (inputfptr == NULL)
   {
       printf("Cannot open file %s \n", "example.txt");
       exit(0);
   }

   // Open another file for writing
   ouputfptr = fopen("output.txt", "w");
   if (ouputfptr == NULL)
   {
       printf("Cannot open file %s \n", "output.txt");
       exit(0);
   }

   // Read contents from file
   c = fgetc(inputfptr);
   int k = 0;
   while (c != EOF)
   {
   char temp[50];
   if(c!=' ')
   {
   temp[k++] = c;
   }
   else
   {
   int t = 1;
   for(int m=0;m<k;m++)
   {
   if(isalpha(temp[m])){}
   else{t=0;break;}
   }
   if(t==1)
   {
   for(int m=0;m<k;m++)
   {
       fputc(temp[m], ouputfptr);
   }
   fputc(' ', ouputfptr);
   }
   k=0;
   }
       c = fgetc(inputfptr);
   }

   printf("\nContents copied to %s", "output.txt");

   fclose(inputfptr);
   fclose(ouputfptr);
   return 0;
}