I've wchar_t type string which includes unicode characters like "ş, ç, ü,.."
I need to take this character one by one from string but I can't read them with sscanf. I couldn't found alternative function. So what should I do?
Related
I came across a line like
char* template = "<html><head><title>%i %s</title></head><body><h1>%i %s</h1> </body></html>";
while reading through code to implement a web server.
I'm curious as I've never seen a string like this before - is template specifying a special type of string (I'm just guessing here because it was highlighted on my IDE)? Also, how would strlen() work with something like this?
Thanks
char* template = "<html>...</html>";
is fundamentally no different than
char *s = "hello";
The name template is not special, it's just an ordinary identifier, the name of the variable. (template happens to be a keyword in C++, but this is C.)
It would be better to define it as const, to enforce the fact that string literals cannot be modified, but it's not mandatory.
Note that template itself is not a string. It's a pointer to a string. The string itself (defined by the language as "a contiguous sequence of characters terminated by and including the first null
character") is the sequence starting with "<html>" and ending with "</html>" and the implicit terminating null character.
And in answer to your second question, strlen(template) would work just fine, giving you the length of the string (81 in this case).
I imagine that there is another part of the code that uses this string to format an output string used as a page by the web server. The strlen function will return the length of the string.
Unless there's a null character somewhere in the initializer or an escape sequence using a \ character, which there isn't, there's nothing special about this string. A % is a normal character in a string and doesn't receive special treatment. The strlen function in particular will read %i as two characters, i.e. % and i. Similarly for %s.
In contrast, a \ is a special character for string and denotes an escape sequence. The \ and the character that follows it in the string constant constitute a single character in the string itself. For example, \n means a newline character (ASCII 10) and \t is a tab character (ASCII 8).
This string is most likely used as a format string for printf. This function will read the string and interpret the %i and %s as format string accepting a int and a char * respectively.
char* template = "<html>...</html>";
just create a char array to store data "<html>...</html>",and this array name is template,you can change this name to other name you want.When create char array,compiler will add \0 to the end of array.strlen will calculate the length from array start to \0(\0 is no include).
I think your IDE will highlight this string is because this string is used in other place.
I don't know the following cases in GCC, who can help me?
Whether a valid UTF-8 character (except code point 0) still contains zero byte? If so, I think function such as strlen will break that UTF-8 character.
Whether a valid UTF-8 character contains a byte whose value is equal to '\n'? If so, I think function such as "gets" will break that UTF-8 character.
Whether a valid UTF-8 character contains a byte whose value is equal to ' ' or '\t'? If so, I think function such as scanf("%s%s") will break that UTF-8 character and be interpreted as two or more words.
The answer to all your questions are the same: No.
It's one of the advantages of UTF-8: all ASCII bytes do not occur when encoding non-ASCII code points into UTF-8.
For example, you can safely use strlen on a UTF-8 string, only that its result is the number of bytes instead of UTF-8 code points.
According to the reference for wcstombs, wcstombs will translate wide-characters "until a wide character translates into a null character."
So what wide-characters are translated into a null multibyte? Is it a specific character? Or any character outside a given range?
The wcstombs function will translate until the L'\0' character (the wide character NUL) is encountered in the wide string (or until the destination multibyte string is filled). That documentation describes what it does when it encounters an error.
I have this hex string:
\x5c30\x3032\x5f5c\x3337\x345c\x3334\x366f\x5c32\x3633\x5c30\x3136\x5c32\x3132\x5c32\x3234\x4e5c\x3236\x335c\x3231\x335c\x3337\x355c\x3335\x315c\x3232\x365c\x3337
How could I convert it to a NSString or NSData? I though of using C methods, but I'm not experienced in C :(
Looks like Unicode characters (specifically, CJK ideographs) to me.
Use an NSScanner to scan the string. Scan up to a backslash, and add whatever you scanned to a mutable string. Then, scan the backslash and throw it away, and then scan the x and throw that away.
Then, scan four single characters, which will be the digits (NSScanner doesn't have a method to scan a single character, so you will need to get them yourself using characterAtIndex: and then adjust the scanner's scan location accordingly). Perform the appropriate conversion of the hexadecimal digit characters to numbers and the math to assemble a single number from them, and you will have the code point (character value) represented by the escape sequence. Add that single character to your string.
Repeat that until you run out of input string, and you will have converted the input string with all its escape sequences into a string with the unescaped characters.
i have a file containing UTF-16 characters. i read in the file and can store the characters either in a uint16_t array or a char array (any better choice?)
But how do i print those characters?
I'm assuming you want to print to stdout or stderr. One method would be to use libiconv to convert from UTF-16 to UTF-32 (also known as UCS-4) into a wide-character string (wchar_t). You could then use wprintf and friends to print to the standard streams.