Write a program to “fold” long input lines into two or more shorter lines after the last nonblank character that occurs before the n-th column of input. Make sure your program that does something intelligent with very long lines, and if there are no blanks or tabs before the specified column.

#include <stdio.h>

#define      MAXCOL    10    /*maximum column of input */
#define      TABINC     8      /* tab increment size */

char line[MAXCOL];           /*input line            */
int exptab(int pos);
int findblnk(int pos);
void newpos(int pos);
void printl(int pos);

/*fold long input lines int two or more shorter lines  */
int main(){
     int c, pos;

      pos = 0;   /* position in the line */
      while((c =getchar()) != EOF){
           line[pos] = c;    /* store current character */
           if(c == '\t')    /* expand tab character */
               pos = exptab(pos);
            else if (c =='\n'){
                 printl(pos);    /*print current input line */
                 pos = 0;
            }else if (++pos >= MAXCOL) {
                   pos =findblnk(pos);
                   printl(pos);
                   pos = newpos(pos);
             }
      }
}
/*printl: print line until pos column            */
void printl(int pos){ 
     int i;
     for(i =0; i< pos; ++i)
         putchar(line[i]);
      if(pos > 0)     /*any chars printed?   */
         putchar('\n');
}
/*exptab: expand tab into blanks   */
int exptab(int pos){
    line[pos] = ' ';     /*tab is at least one blank */
    for(++pos; pos < MAXCOL && pos % TABINC != 0; ++pos)
         line[pos] = ' ';
    if (pos < MAXCOL)   /* room left in current line   */
        return pos;
    else{
          printl(pos);
          return 0;      /*reset current position */
   }
}
/* findblnk: find blank's position */
int findblnk(int pos){
    while(pos >0 && line[pos] != ' ')
           --pos;
    if(pos == 0)   /*no blanks in the line  */
        return MAXCOL;
    else        /* at least one blank */
      return pos + 1;    /*position after blank */
        
}
/*newpos: rearrange line into new position    */
int newpos(int pos){
     int i, j;

     if (pos <= 0 || pos >= MAXCOL)
          return 0;
     else{
          i = 0;
         for(j =pos; j < MAXCOL; ++j){
             line[i] = line[j];
             ++i;
         }
           return i;     /* new position in line    */
     }
}