K&R Exercise 1-20: detab

gistfile1.c

#include <stdio.h>

#define MAXLINE 1000
#define TABWIDTH 4

int slurp_into(char input[]);
void output_detabbed(char input[], int length);
void output_spaces(int how_many);

int main()
{
        char input[MAXLINE];
        int length;

        length = slurp_into(input);
        output_detabbed(input, length);

        return 0;
}

int slurp_into(char input[])
{
        int i;
        int c;

        for (i = 0; i < MAXLINE-1 && (c = getchar()) != EOF; ++i) {
                input[i] = c;
        }

        return i;
}

void output_detabbed(char input[], int length)
{
        int i;
        int line_position = 0;

        for (i = 0; i < length; ++i) {
                if (input[i] == '\n') {
                        putchar(input[i]);
                        line_position = 0;
                }
                else if (input[i] == '\t') {
                        output_spaces(TABWIDTH - (line_position % TABWIDTH));
                }
                else {
                        putchar(input[i]);
                        ++line_position;
                }
        }
}

void output_spaces(int how_many)
{
        int i;

        for (i = 0; i < how_many; i++) {
                putchar(' ');
        }
}