It's anyways bad practice to initialie a char array with a string literal.
The author of that comment never really justifies it, and I find the statement puzzling.
In C (and you've tagged this as C), that's pretty much the only way to initialize an array of char
with a string value (initialization is different from assignment). You can write either
char string[] = "october";
or
char string[8] = "october";
or
char string[MAX_MONTH_LENGTH] = "october";
In the first case, the size of the array is taken from the size of the initializer. String literals are stored as arrays of char
with a terminating 0 byte, so the size of the array is 8 ('o', 'c', 't', 'o', 'b', 'e', 'r', 0). In the second two cases, the size of the array is specified as part of the declaration (8 and MAX_MONTH_LENGTH
, whatever that happens to be).
What you cannot do is write something like
char string[];
string = "october";
or
char string[8];
string = "october";
etc. In the first case, the declaration of string
is incomplete because no array size has been specified and there's no initializer to take the size from. In both cases, the =
won't work because a) an array expression such as string
may not be the target of an assignment and b) the =
operator isn't defined to copy the contents of one array to another anyway.
By that same token, you can't write
char string[] = foo;
where foo
is another array of char
. This form of initialization will only work with string literals.
EDIT
I should amend this to say that you can also initialize arrays to hold a string with an array-style initializer, like
char string[] = {'o', 'c', 't', 'o', 'b', 'e', 'r', 0};
or
char string[] = {111, 99, 116, 111, 98, 101, 114, 0}; // assumes ASCII
but it's easier on the eyes to use string literals.
EDIT2
In order to assign the contents of an array outside of a declaration, you would need to use either strcpy/strncpy
(for 0-terminated strings) or memcpy
(for any other type of array):
if (sizeof string > strlen("october"))
strcpy(string, "october");
or
strncpy(string, "october", sizeof string); // only copies as many characters as will
// fit in the target buffer; 0 terminator
// may not be copied, but the buffer is
// uselessly completely zeroed if the
// string is shorter!