检查C中的特殊字符

Question

I got some help on how to see if a "string" in C contains a specific character. In short:

if(*s=='x') { //Where x is some character
    //Do something
}

Now, as far as I can see, this works for letters in the English alphabet (az, AZ).

However, how can I check if the current character equals a special character (such as æ , ø , or å )?

Answer 1

In most cases you should be using a function for this: strchr for looking for a single byte, or strstr for looking for more than a single byte.

Also, in general C does not know about characters, it only knows about bytes. A special character may be a single byte - æ in iso8859-1 encoding is \\xe6 , for example - or it may be more than one byte: the same character in utf-8 encoding is the 2-byte sequence \\xc3\\xa6 .

To search a utf-8 encoded string for æ you could use

strstr(s, "\xc3\xa6")

Answer 2

Just compare to the ASCII code of the character:

if(*s==10) { //Where 10 is the ASCII code of the special character
    //Do something
}

You can find your ASCII code here: http://www.asciitable.com/

Answer 3

Compare the character to the actual value (as long as the value is between 0 and 255).

See the æ wiki page for particular values. So

if (*s == 0xe6)

for lower case

if (*s == 0xc6)

for upper case