3 questions on wchar_t

[arnuld]

int main(void)
{
wchar_t a = 'a';

char my_a = a;

printf("wchar_t a = %c\n", a);
printf("char my_a = %c\n", my_a);


return 0;
}

============== OUTPUT ==============
[arnuld@dune programs]$ gcc -std=c99 -pedantic -Wall -Wextra test.c
test.c: In function `main':
test.c:13: warning: int format, wchar_t arg (arg 2)
[arnuld@dune programs]$




I have 3 questions:

is it safe, when I am sure thar wchar_t holds only normal alphanumeric
characters like a-z, A-Z and 0-9 ??

is there a way to print wchar strings

is there a way to convert a wchar_t to char ?

 

[Harald van Dijk]

int main(void)
{
wchar_t a = 'a';

You should assign L'a'. It need not have the same numeric value as 'a'.

char my_a = a;

You should assign 'a' instead of relying on an implicit wchar_t->char
conversion, which won't always do the right thing.

printf("wchar_t a = %c\n", a);
printf("char my_a = %c\n", my_a);


return 0;
}

============== OUTPUT ==============
[arnuld@dune programs]$ gcc -std=c99 -pedantic -Wall -Wextra test.c
test.c: In function `main':
test.c:13: warning: int format, wchar_t arg (arg 2) [arnuld@dune
programs]$




I have 3 questions:

is it safe, when I am sure thar wchar_t holds only normal alphanumeric
characters like a-z, A-Z and 0-9 ??

No, for the same reason that

printf("%d\n", 0L);

is not safe even though 0L is in range for an int.

is there a way to print wchar strings

Yes. %lc and %ls print wint_t and wchar_t[] values. For a single wchar_t,
cast it to wint_t and use %lc.

is there a way to convert a wchar_t to char ?

wctob can do that. It will either give you a valid result in the range of
unsigned char -- convert that to char if you like -- or it will give you
EOF if the character would take up more than one byte.

 

[Mark Wooding]

is it safe, when I am sure thar wchar_t holds only normal alphanumeric
characters like a-z, A-Z and 0-9 ??
No.

is there a way to print wchar strings

A `%ls' conversion specifier to `printf' and chums; `fputws', if your
output file has the appropriate orientation.

is there a way to convert a wchar_t to char ?

`wctob' or `wcrtomb'. Or you can mess around with `wctomb' if you don't
have other threads to worry about.

-- [mdw]