UNIX for Dummies Questions & Answers

/*********************************
* block.c 
* to compile:
*  gcc -o block block.c
*  or 
*  cc -o block block.c
*  
* usage:  block [filename] > outputfile  
*
**********************************/
#include <stdio.h>
#include <stdlib.h>

int main(int argc, char *argv[1])
{
    int ch=0;
    int counter=0;
    FILE *in=NULL;
    if(*argv[1])
    {
        in=fopen(argv[1],"r");	
            if(in==NULL)
        {
            perror("");
            exit(EXIT_FAILURE);
        }
    }
    else
    {
        in=stdin;	
    }
    while( (ch=fgetc(in))!=EOF)
    {
        fprintf(stdout,"%c", ch);
        counter++;
        if(counter%160 == 0)
        {
            fprintf(stdout,"\n");
        }
    }
    if(counter%160)
    {
        while(counter%160)
        {
            fprintf(stdout,"%c",' ');
            counter++;
        }
        fprintf(stdout,"\n");
    }
    return 0;
}