Which method is correct for Initializing a wchar_t string?
I am writing a program and I need to initialize a message buffer which will hold text. I am able to make it work, however I am writing below various ways used to initialize the strings in C and I want to understand the difference. Also, which is the most appropriate method for initializing a wchar_t/char string?
Method I:
wchar_t message[100];
based on my understanding, this will allocate a memory space of 200 bytes (I think size of wchar_t is 2 bytes on Windows OS). This memory allocation is static and it will be allocated inside the .data section of the executable at the time of compiling.
message is also a memory address itself that points to the first character of the string.
This method of initializing a string works good for me.
Method II:
wchar_t *message;
message=(wchar_t *) malloc(sizeof(wchar_t) * 100);
This method will first initialize the variable message as a pointer to wchar_t. It is an array of wide characters.
next, it will dynamically allocate memory for this string. I think I have written the syntax for it correctly.
When I use this method in my program, it does not read the text after the space in a string.
Example text: "This is a message"
It will read only "This" into the variable message and no text after that.
Method III:
wchar_t *message[100];
This will define message as an array of 100 wide characters and a pointer to wchar_t. This method of initializing message works good. However, I am not sure if it is the right way. Because message in itself is pointing to the first character in the string. So, initializing it with the size, is it correct?
I wanted to understand it in more depth, the correct way of initializing a string. This same concept can be extended to a string of characters as well.
Answer
The magic is the encoding-prefix L:
#include <wchar.h>
...
wchar_t m1[] = L"Hello World";
wchar_t m2[42] = L"Hello World";
wchar_t * pm = L"Hello World";
...
wcscat(m2, L" again");
pm = calloc(123, sizeof *pm);
wcspy(pm, L"bye");
See also the related part of the C11 Standard.