C + + string conversions

character classification functions convert character function strings to numeric values need to be clear plus # include<ctype.h>function Islower Tests whether lowercase letters are returned nonzero, otherwise returns 0. Isupper tests whether the uppercase letter is returned nonzero, otherwise returns 0. isalpha test whether the letter, Returns nonzero, otherwise 0. isalnum tests whether the number is returned nonzero, otherwise returns 0. The Iscntrl test controls whether the character is returned nonzero, otherwise returns 0. Isprint tests whether the printable character is returned nonzero, otherwise returns 0. The Isgraph tests whether the printable character, without spaces, is returned nonzero, otherwise 0 is returned. IsDigit whether the test is a character'0'~'9', which is nonzero, returns 0 otherwise. Isblank tests whether the standard white space character is returned nonzero, otherwise returns 0. The Isspace tests whether the whitespace character is returned nonzero, otherwise returns 0. ISPUNCT tests whether punctuation is returned nonzero, otherwise returns 0. Convert case toupper convert lowercase to uppercase if not character returns the original value ToLower convert uppercase to lowercase if not character returns the original value string converted to a value need to add # include<stdlib.h>atof Convert from string to double type atoi from string tointtype Atol convert from string toLongtype Atoll convert from string toLong LongType Example:

C + + string conversions