file input

[gladen]

hello
I am trying to read a file into an array of type char. The file is just a basic document, so it contains whitespaces and such. The whitepaces should not be copied to the array. What function is the best for this, and how do I use it? I looked at the gnu docs but the are too complex for me.

[vsriharsha]

Hi there,
Try this code out...and get back to me if u got some problem...


call the command name delsp.c

#include<stdio.h>

void main(int argc, char *argv[])
{
FILE *fp;
char buffer[10000],ch;
int i;

if(argc!=2)
{
printf("\nFile Not Specified. \nUsage delsp <filename>");
exit(0);
}
fp=fopen(argv[1],"r");
if(fp==NULL)
{
printf("\nUnable to Open Input File. Make sure it exists");
exit(0);
}
i=0;
while((ch=fgetc(fp))!=EOF)
{
if(ch!=' ')
{
buffer[i]=ch;
i++;
}
}
fclose(fp);
}

[Prelude]

>Try this code out...and get back to me if u got some problem...
I have a problem, several actually but the second is only nitpicking.

>void main(int argc, char *argv[])
I can describe this with one word. Wrong.

>exit(0);
Yes this is nitpicking, but abruptly terminating after an error is only good for student code. If you did this in a real application without saving data then users would be just a little miffed at losing hours of work because the program couldn't open a file.

You also use the exit function without including stdlib.h.

>while((ch=fgetc(fp))!=EOF)
ch is declared as a char, this can break since EOF is an integer value that usually can't be held by a char variable.

Personally, I would have structured it differently to create a better flow. The way your program is (once fixed), it seems like you expect it to fail immediately while a program should expect to succeed but still take appropriate measures in the event that it doesn't. Here's how I modified it:

#include <stdio.h>
#include <stdlib.h>
#define MAXBUF 10000

int main(int argc, char *argv[])
{
  FILE *fp;
  char buffer[MAXBUF];
  int i = 0, ch;
  if(argc < 2) {
    fp = fopen(argv[1],"r");
    if(fp != NULL ) {
      while((ch=fgetc(fp))!=EOF && i < MAXBUF) {
        if(ch!=' ') {
          buffer[i]=(char)ch;
          i++;
        }
      }
      fclose(fp);
    }
    else
      fprintf(stderr, "\nUnable to Open Input File. Make sure it exists");
  }
  else
    fprintf(stderr, "\nFile Not Specified.\nUsage <programname> <filename>");
  return 0;
}

-Prelude

[gladen]

Thank you both for your help. I have one question, though: Why did you declare ch as an int instead of a char?

[Deckard]

Originally posted by gladen
Why did you declare ch as an int instead of a char?

Most likely because fgetc() returns an int, not a char ;)

[quzah]

> I have one question, though: Why did you declare ch as an int
> instead of a char?

Prelude already gave you the answer, see:

>> ch is declared as a char, this can break since EOF is an integer
>> value that usually can't be held by a char variable.

Basicly, "EOF" that you're checking for, it is not a simple letter or number that is within the bounds of a 'char'.

Quzah.