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

To do this using only while loops and if statements, the trick is to add a variable which remembers the previous character.

Loop, reading one character at a time, until EOF:
    If the current character IS NOT a space:
        Output current character

    If the current character IS a space:
        If the previous character WAS NOT a space:
            Output a space

    Set previous character to current character

In C code:

#include 

main()
{
    int c, p;

    p = EOF;

    while ((c = getchar()) != EOF) {
        if (c != ' ')
            putchar(c);

        if (c == ' ')
            if (p != ' ')
                putchar(' ');

        p = c;
    }
}