INF2270
		 Løsningsforslag oppgaver uke 6 2010

Oppgave 1

#define STREQ(s1,s2) (strcmp((s1),(s2))==0)


Oppgave 2

Det finnes mange løsninger, blant annet

    x = MIN(a,b) + 1;
    x = 1 - MIN(a,4);

Disse vil bli ekspandert til henholdsvis

    x = a<b ? a : b+1;
    x = 1-a<4 ? a : 4;

(Jeg har justert litt med blanke tegn for å gjøre det tydeligere
hvorledes C-kompilatoren vil oppfatte uttrykket.)


Oppgave 3

#include <ctype.h>
#include <stdio.h>

int main(int argc, char *argv[])
{
  FILE *f;
  int nc = 0, nw = 0, nl = 0, /* Antall tegn, ord, linjer */
      c, 
      in_word = 0;

  if (argc != 2) {
    printf("Usage: wc file\n");  return 1;
  }
  f = fopen(argv[1],"r");
  if (f == NULL) {
    printf("wc: %s: No such file or directory\n", argv[1]);
    return 2;
  }

  c = fgetc(f);
  while (c != EOF) {
    nc++;
    if (c == '\n') nl++;
    if (isspace(c)) {
      in_word = 0;
    } else {
      if (! in_word) nw++;
      in_word = 1;
    }
    c = fgetc(f);
  }
  fclose(f);

  printf("%8d%8d%8d %s\n", nl, nw, nc, argv[1]);
  return 0;
}


Oppgave 4

#include <stdio.h>
#include <stdlib.h>
#include <string.h>

struct line_struct {
  struct line_struct *next;
  char contents[204];
};
typedef struct line_struct line;

line *read_all_lines (void)
{
  line *first = NULL, *last = NULL, *cur;
  char cur_line[204];
  
  while (fgets(cur_line,200,stdin) != NULL) {
    cur = malloc(sizeof(line));
    strcpy(cur->contents, cur_line);

    /* Insert this line last in the list: */
    if (first == NULL) {
      first = cur;  last = cur;
    } else {
      last->next = cur;  last = cur;
    }
    last->next = NULL;
  }
  return first;
}

void print_all_lines (line *lp)
{
  while (lp) {
    printf("%s", lp->contents);
    lp = lp->next;
  }
}

int main (void)
{
  line *data = read_all_lines();
  print_all_lines(data);
  return 0;
}