c/c++判别字符是不是字母以及大小写相应转换的函数

isalnum Check if character is alphanumeric (function ) 判断是不是字母数字 isdigit Check if character is decimal digit (function ) 判断是不是数字 isalnum Check if character is alphanumeric (function ) isalpha Check if character is alphabetic (function ) isblank Check if character is blank (function ) iscntrl Check if character is a control character (function ) isdigit Check if character is decimal digit (function ) isgraph Check if character has graphical representation (function ) islower //判断是不是小写字母 Check if character is lowercase letter (function ) isprint Check if character is printable (function ) ispunct Check if character is a punctuation character (function ) isspace Check if character is a white-space (function ) isupper //判断是不是大写字母 Check if character is uppercase letter (function ) isxdigit Check if character is hexadecimal digit (function )