field `chars' has incomplete type

[Unregistered]

Need to get over this hump to see how the rest of my codes are going. Here's a snippet of myString.h

struct String
{
char chars[];
};

typedef struct String * String;

I decided to represent a String as an array of char. But whenever I try to compile mystring.c (which includes "mystring.h") the message appears:

mystring.h:9: field `chars' has incomplete type

Please reply soon.

[Hammer]

Originally posted by Unregistered

struct String
{
char chars[];
};

This should be declared in one of these ways:

char chars[100]; /* or whatever size you want */
char *chars;

The first will give you 100 bytes of memory automatically, the second will give you a pointer, for which you will need to malloc memory to hold your string. As you're beginning, start with option 1, its easier to get to grips with.

[Prelude]

If you declare an array, then you must give it a size immediately. This can be done with a constant value such as in

char chars[10];

Or with an initialization list:

char chars[] = "Some string";

If you want to set the size later, then you must declare chars as a pointer to char and allocate the memory when you need it:

char *chars;
.
.
.
if ( ( chars = malloc ( n * sizeof *chars ) ) != NULL ) {
  /* Work with the array */
  free ( chars );
}

-Prelude