Char Functions

    atof        convert string into floating point
    atoi        convert string into integer
    atol        convert string into long integer
    isalnum     is character alphanumeric?
    isalpha     is character alphabetic?
    iscntrl     is character a control character?
    isdigit     is character numeric?
    isgraph     is character graphic?
    islower     is character lower case?
    isprint     is character printable?
    ispunct     is character punctuation?
    isspace     is character whitespace?
    isupper     is character upper case
    isxdigit    is character hex digit
    tolower     convert character to lower case
    toupper     convert character to upper case