CODEWITHSUNDEEP
cpointers
SeanIvins
SeanIvins

Reputation: 39

Pointer Fun in C. Why won't this compile?

I always thought I was an intelligent person until I started learning programming. This is a small example of something that wouldn't compile

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

int main()
{
  char* dictionary;
  dictionary = malloc(sizeof(char) * 3);
  *dictionary = "ab";
  char c = dictionary[0];
  int i = 0;
  while (c != "b")
  {
    printf("%c\n", c);
    i++;
    c = dictionary[i];
  }
}

error.c:8:15: error: incompatible pointer to integer conversion assigning to 'char' from 'char [3]' *dictionary = "ab";

error.c:11:12: error: result of comparison against a string literal is unspecified (use strncmp instead) while (c != "b")

error.c:11:12: error: comparison between pointer and integer ('int' and 'char *') while (c != "b")

Upvotes: 0

Views: 314

Answers (2)

doog abides
doog abides

Reputation: 2288

You're codes are not correct. Not even a little.. kinda makes me think it's a homework assignment.. but here's a few hints.

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

int main()
{
  char* dictionary;
  dictionary = malloc(sizeof(char) * 3); /* ok, I expect to see a free later */
  *dictionary = "ab"; /* assigning a string literal to a dereferenced char *..
                      /* maybe we should use strncpy..  */
  char c = dictionary[0];
  int i = 0;
  while (c != "b") /* hmm.. double quotes are string literals.. maybe you mean 'b' */
  {
    printf("%c\n", c);
    i++;
    c = dictionary[i];
  }
  /* hmm.. still no free, guess we don't need those 3 bytes.
     int return type.. probably should return 0 */
}

Upvotes: 1

Beirdo
Beirdo

Reputation: 424

Along with the single quotes in the while, you cannot do *dictionary = "ab".

When you dereference a char * (by doing *dictionary) the result is a single char. You can initialize a char * to point to a string though. That would be if you do all in one line:

char *dictionary = "ab";

Otherwise, you should do:

#include <string.h>

strcpy(dictionary, "ab");

Upvotes: 1

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