1-21

1-21.c

#include <stdio.h>
#define MAXCHAR 100
#define TABSTOP 6

void entab();

int main(){
  int c;
  char str[MAXCHAR];
  int i, j;
  i = 0;
  while((c = getchar()) != EOF){
    str[i++] = c;
    if(c == '\n'){
      entab(str);
      for(j = 0; str[j] != '\n'; j++){
        printf("%c", str[j]);
      }
      printf("\n");
      i = 0;
    }
  }
}

void entab(char str[]){
  int i;
  int tno = 0;
  int sno = 0;
  int j = 0;

  for(i = 0; str[i] != '\n'; i++){
    if(str[i] == '\t'){
      tno += 1;
    }else if(str[i] == ' '){
      sno += 1;
    }else{
      return;
    }
  }

  tno += sno / TABSTOP;
  sno = sno % TABSTOP;
//  printf("t:%d\n", tno);
//  printf("s:%d\n", sno);
  for(;(j < tno) && j < MAXCHAR; j++){
    str[j] = '\t';
  }
  for(; (j < sno) && j < MAXCHAR; j++){
    str[j] = ' ';
  }
  str[j++] = '\n';
  for(; j < MAXCHAR; j++){
    str[j] = '\0';
  }
return;
}