exercise1-9.c

#include <stdio.h>

int main(void)
{
    int c, blanks;

    blanks = 0; // recognize whether there is a blank after a character
    while ((c = getchar()) != EOF) {
        if (c == ' ') {
            if (blanks == 0) {
                putchar(c);
                blanks = 1;
            }
        }

        if (c != ' ') {
            putchar(c);
            blanks = 0;
        }
    }

    return 0;
}


/*
int main(void)
{
    int current, previous; // current = current character, previous = previous character

    // set previous to a value that wouldn't match any character
    previous = EOF;
    while ((current = getchar()) != EOF) {
        if (current == ' ') {
            if (previous != ' ')
                putchar(current);
        }
        if (current != ' ')
            putchar(current);
        previous = current;
    }

    return 0;
}
*/

/*
int main(void)
{
    int current, previous; // current = current character, previous = previous character

    // set previous to a value that wouldn't match any character
    previous = EOF;
    while ((current = getchar()) != EOF) {
        if (!((current == ' ') && (previous == ' ')))
            putchar(current);
        previous = current;
    }

    return 0;
}
*/

/*
int main(void)
{
    int current;

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

    return 0;
}
*/