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

Like many other people, I am studying this book as well and found this question very interesting.

I have come up with a piece of code that only uses what has been explained before the exercice (as I am not consulting any other resource but just playing with the code).

There is a while loop to parse the text and one if to compare the current character to the previous one. Are there any edge cases where this code would not work ?

#include 

main() {

    // c    current character
    // pc   previous character
    int c, pc;

    while ((c = getchar()) != EOF) {
        // A truthy evaluation implies 1 
        // (learned from chapter 1, exercice 6)
        // Avoid writing a space when 
        //  - the previous character is a space (+1)
        //  AND
        //  - the current character is a space (+1)
        // All the other combinations return an int < 2
        if ((pc == ' ') + (pc == c) < 2) {
            putchar(c);
        }
        // update previous character
        pc = c;
    }

}