c_ch01_ex20.c

/*Exercise 1-20. Write a program detab that
replaces tabs in the input with the proper
number of blanks to space to the next tab
stop. Assume a fixed set of tab stops, say
every n columns. Should n be a variable or
a symbolic parameter?*/
#include <stdio.h>
#define MAX     1000
char str[MAX];
int detab(int len);
int main()
{
        int len;
        while ((len = detab(MAX)) > 0)
                printf("%s\n", str);
        return 0;
}
int detab(int len) {
        int c, i, j, t, temp, remainder;
        i = t = j = remainder = 0;
        while ((c = getchar()) != EOF && c != '\n' && i < len - 1 ) {
                if (i > 8)
                        remainder= i % 8;
                if (c != '\t') {
                        if (t) {
                                if (i > 8) {
                                        while (j < (t - remainder)) {
                                                str[i++] = ' ';
                                                j++;
                                        }
                                } else {
                                        temp = i;
                                        while (j < (t - temp)) {
                                                str[i++] = ' ';
                                                j++;
                                        }
                                }
                                t = j = 0;
                        }
                        str[i++] = c;
                } else
                        t += 8;
        }
        if (t) {
                if (i > 8) {
                        while (j < (t - remainder)) {
                                str[i++] = ' ';
                                j++;
                        }
                } else {
                        temp = i;
                        while (j < (t - temp)) {
                                str[i++] = ' ';
                                j++;
                        }
                }
        }
        str[i] = '\0';
        return i;
}