Thread: Easy Exercise 1

Hello guys, I'm a beginner in programming. I've just come across the problem in K&R2: Write a program to copy its input to its output, replacing each string of one or more blanks by a single blank.I also found a solution, but i have some questions about it. First: what does it mean "inspace=0 ?" what is done by this? and what does " inspace=1" mean? How does the program affect blanks?

Code:

 #include<stdio.h>
int main(void)
{
  int c;
  int inspace;

  inspace = 0;
  while((c = getchar()) != EOF)
  {
    if(c == ' ')
    {
      if(inspace == 0)
      {
        inspace = 1;
        putchar(c);
      }
    }

    /* We haven't met 'else' yet, so we have to be a little clumsy */
    if(c != ' ')
    {
      inspace = 0;
      putchar(c);
    }
  }

  return 0;
}

i have questions about the second solution. what does it mean at the end "pc=c"? for what reason is it used? and could you explain why we take "pc=EOF"? what happens with this assignment? Sorry for my easy questions, but i really could not find answers to these.

Code:

#include <stdio.h>

/* count lines in input */
int
main()
{
        int c, pc; /* c = character, pc = previous character */

        /* set pc to a value that wouldn't match any character, in case
        this program is ever modified to get rid of multiples of other
        characters */

        pc = EOF;

        while ((c = getchar()) != EOF) {
                if (c == ' ')
                        if (pc != ' ')   /* or if (pc != c) */ 
                                putchar(c);

                /* We haven't met 'else' yet, so we have to be a little clumsy */
                if (c != ' ')
                        putchar(c);
                pc = c;
        }

        return 0;
}

please help me

There is a big difference between writing a solution and finding a solution on the web.

The first one forces you to work out the problem. I suggest you try that; who knows, it might even be fun.