K&R Exercise 1-9 (C)

Question

\"Write a program to copy its input to its output, replacing each string of one or more blanks by a single blank.\"

I\'m assuming by thi

Answer 1

I am also starting out with the K&R textbook, and I came up with a solution that uses only the material which had been covered up until that point.

How it works:

First, set some counter 'blanks' to zero. This is used for counting blanks.

If a blank is found, increase the counter 'blanks' by one.

If a blank is not found, then first do a sub-test: is the counter 'blanks' equal or bigger than 1? If yes, then first, print a blank and after that, set the counter 'blanks' back to zero.

After this subtest is done, go back and putchar whatever character was not found to be a blank.

The idea is, before putcharing a non-blank character, first do a test to see, if some blank(s) were counted before. If there were blanks before, print a single blank first and then reset the counter of blanks. That way, the counter is zero again for the next round of blank(s). If the first character on the line is not a blank, the counter couldn't have increased, hence no blank is printed.

One warning, I haven't gone very far into the book, so I'm not familiar with the syntax yet, so it's possible that the {} braces might be written in different places, but my example is working fine.

#include 

/* Copy input to output, replacing each string of one or more blanks by a single blank. */

main()
{
    int c, blanks;

    blanks = 0;
    while ((c = getchar()) != EOF) {
        if (c != ' ') {
            if (blanks >= 1)
                printf(" ");
                blanks = 0;
            putchar(c); }
        if (c == ' ')
            ++blanks;
    }
}