Question

This is a follow-up to my previous question . I succeeded in implementing the algorithm for checking umlauted characters. The next problem comes from iterating over all characters in a string. I do this like so:

int main()
{
    char* str = "Hej du kalleåäö";
    printf("length of str: %d", strlen(str));

    for (int i = 0; i < strlen(str); i++)
    {
        printf("%s ", to_morse(str[i]));
    }
    putchar( 
 );
    return 0;
}

The problem is that, because of the umlauted characters, it prints 18, and also makes the to_morse function fail (ignoring these characters). The toMorse method accepts an unsigned char as a parameter. What would be the best way to solve this? I know I can check for the umlaut character here instead of the letterNr function but I don t know if that would be a pretty/logical solution.

Answer 1

Normally, you d store the string in a wchar_t and use something like ansi_strlen to get the length of it - that would give you the number of printed characters as opposed to the number of bytes you stored.

You really shouldn t be implementing UTF or Unicode or whatever multibyte character handling yourself - there are libraries for that sort of thing.

Answer 2

On OS X, Cocoa is a solution - note the use of "%C" in NSLog - that s an unichar (16-bit Unicode character):

#import <Cocoa/Cocoa.h>

int main()
{
        NSAutoreleasePool * pool = [NSAutoreleasePool new];
        NSString * input = @"Hej du kalleåäö";

        printf("length of str: %d", [input length]);
        int i=0;
        for (i = 0; i < [input length]; i++)
        {
                NSLog(@"%C", [input characterAtIndex:i]);
        }

        [pool release];
}

Answer 3

You could do something like

for (int i = 0; str[i]!=  ; ++i){
    //do something with str[i]
}

Strings in C are terminated with . So it is possible to check for the end of the string like that.

Answer 4

EDIT: What locale are you using?

If you are going to iterating over a string, don t bother with getting its length with strlen. Just iterate until you see a NUL character:

char *p = str;
while(*p !=   ) {
    printf("%c
", *p);
    ++p;
}

As for the umlauted characters and such, are they UTF-8? If the string is multi-byte, you could do something like this:

size_t n = strlen(str);
char *p = str;
char *e = p + n;
while(*p !=   ) {
    wchar_t wc;
    int l = mbtowc(&wc, p, e - p);
    if(l <= 0) break;
    p += l;
    /* do whatever with wc which is now in wchar_t form */
}

I honestly don t know if mbtowc will simply return -1 if it encounters a NUL in the middle of a MB character. If it does, you could just pass MB_CUR_MAX instead of e - p and do away with the strlen call. But I have a feeling this is not the case.

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