• toupper converte e restituisce nella forma maiuscola il carattere passato in codice ASCII
• tolower converte e restituisce nella forma minuscola il carattere passato in codice ASCII

da analizzare e tradurre:

• isalnum Check if character is alphanumeric
• isalpha Check if character is alphabetic
• iscntrl Check if character is a control character
• isdigit Check if character is decimal digit
• isgraph Check if character has graphical representation using locale
• islower Check if character is lowercase letter
• isprint Check if character is printable
• ispunct Check if character is a punctuation character
• isspace Check if character is a white-space
• isupper Check if character is uppercase letter
• isxdigit Check if character is hexadecimal digit