简单的方法来区分C中的数字和字母

Question

I'm currently reading in a file, and storing that file into a cstring. I'm using strtok to parse it out for the first few strings i'm interested in. After that, the substrings could be numbers (500,150,30) or character combinations( P(4),(K(5)). Is there an easy method in the string library to differentiate between numbers and letters? \\

Thanks for the answers guys!

Answer 1

If you are sure that there are no other symbols (@#$%^%&*^) you can use the isalpha() function.

Usage:

   isalpha(p);// returns true if its alphabetic and false otherwise.

Also note that you should include ctype.h .

Answer 2

well, if you're reading a stream of bytes and want to differentiate between numbers and letters the following can be done:

// returns true if given char is a character, false otherwise
bool is_letter(char c) {
    return (c >= 'a' && c <= 'z') || (c >= 'A' && c <= 'Z');
}

which is easy enough to implement where it is needed. If you really want a library function, you can still use isalpha() or isdigit() from ctype.h , which basically should do the same thing.

NB: you might want to choose between bool or unsigned short . I won't enter into that debate .

Answer 3

您可能会查找isalpha和isdigit库函数。