entab.c - Program that replaces a string of blanks by the min # of spaces & tabs required to generate identical output

entab.c

#include <stdio.h>

#define TABSIZE 8

int main()
{
    int c, nchars, nspaces;

    //nchars = number of chars, nspaces = number of spaces
    nchars = nspaces = 0;
    while((c = getchar()) != EOF) {

        if(c == ' ') {
            ++nspaces;
        } else {
            //decide whether gap in between chars is long enough for a space
            while(nspaces >= TABSIZE - nchars) {
                putchar('\t');
                nspaces -= TABSIZE;
            }

            //insert all remaining spaces manually
            while(nspaces > 0) {
                putchar(' ');
                --nspaces;
            }

            //at this point nspaces has to be 0, update nchars = 0 as well for correct "endpoint" evaluation
            nchars = 0;

            if(c != '\t') {
                ++nchars;
            }

            putchar(c);
        }
    }

    return 0;
}

Special thanks to CodeReview users who helped me improve the code.

https://codereview.stackexchange.com/questions/187639/entab-c-program-that-replaces-string-of-blanks-by-the-min-of-spaces-tabs-t