Ansi C - Convert String to Lower Case String

Question

I need to convert a char array to a lower case char array. I also want to convert some special characters like Ä to ä. But the "ASCII-Code" 196 isn't in the ASCII-128. How can I convert them to lower case ? I can use them as string initializer but can't really deal with their codes. In case this might be a compiler option I'm using eclipse CDT on Linux without c99 mode (can't use that one).

char* toLowerCase(char* text)
{
    int length = strlen(text);
    char* result = malloc(length); // malloc adds the 0 automatically at result[length]
    int i;
    for (i = 0; i < length; i++)
        if ((text[i] >= 65) && (text[i] <= 90))
            result[i] = text[i] | 32;
        else
            result[i] = text[i];
    return result;
}

toLowerCase("hElLo WoRlD ÄäÖöÜü");
// result is "hello world ÄäÖöÜü"

tolower() from ctype.h doesn't do it either.

Apart from being utterly non-portable, this further extends the misery by being utterly non-high-asci friendly. And you can't use a compiler based on a standard thats only 14 years old? I bet your prof is real popular. — WhozCraig
– WhozCraig, Commented Jan 25, 2013 at 10:22
Please read The Absolute Minimum Every Software Developer Absolutely, Positively Must Know About Unicode and Character Sets (No Excuses!) before you go any further dealing with characters. — pmg
– pmg, Commented Jan 25, 2013 at 10:25
@WhozCraig My prof was pretty popular. But that's not the point and I'm not a lazy student. Despite that I'm also unhappy about it I'm bound to this restrictions. I just solved it on my own anyways. — Bitterblue
– Bitterblue, Commented Jan 25, 2013 at 10:42
Excellent! "was" popular? I hope there isn't a sad end to that story. Anyway, very good for solving it. grats! — WhozCraig
– WhozCraig, Commented Jan 25, 2013 at 10:53

qPCR4vir · Accepted Answer · 2013-01-25 11:48:57Z

3

I think you need to read about setlocale, (or here)

and use tolower()

Notes: During program startup, the equivalent of setlocale(LC_ALL, "C"); is executed before any user code is run.

You can try the Environment's default locale (or select the correct if you know it):

setlocale(LC_ALL, "");

edited Jan 25, 2013 at 11:48

answered Jan 25, 2013 at 10:30

qPCR4vir

3,5821 gold badge24 silver badges32 bronze badges

Sign up to request clarification or add additional context in comments.

Collectives™ on Stack Overflow

Ansi C - Convert String to Lower Case String

1 Answer 1

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

Comments

Your Answer

Sign up or log in

Post as a guest

Related