A null-terminated byte string (NTBS) is a sequence of nonzero bytes followed by a byte with value zero (the terminating null character). Each byte in a byte string encodes one character of some character set. For example, the character array {'x63','x61','x74','�'} is an NTBS holding the string "cat" in ASCII encoding.
Functions
Character classification | |
Defined in header | |
isalnum | checks if a character is alphanumeric (function) |
isalpha | checks if a character is alphabetic (function) |
islower | checks if a character is lowercase (function) |
isupper | checks if a character is an uppercase character (function) |
isdigit | checks if a character is a digit (function) |
isxdigit | checks if a character is a hexadecimal character (function) |
iscntrl | checks if a character is a control character (function) |
isgraph | checks if a character is a graphical character (function) |
isspace | checks if a character is a space character (function) |
isblank (C99) | checks if a character is a blank character (function) |
isprint | checks if a character is a printing character (function) |
ispunct | checks if a character is a punctuation character (function) |
Character manipulation | |
tolower | converts a character to lowercase (function) |
toupper | converts a character to uppercase (function) |
Note: additional functions whose names begin with either to or is, followed by a lowercase letter, may be added to the header ctype.h in future and should not be defined by programs that include that header.
Conversions to numeric formats | |
Defined in header | |
atof | converts a byte string to a floating-point value (function) |
atoiatolatoll (C99) | converts a byte string to an integer value (function) |
strtolstrtoll (C99) | converts a byte string to an integer value (function) |
strtoulstrtoull (C99) | converts a byte string to an unsigned integer value (function) |
strtofstrtodstrtold (C99)(C99) | converts a byte string to a floating point value (function) |
Defined in header | |
strtoimaxstrtoumax (C99)(C99) | converts a byte string to intmax_t or uintmax_t (function) |
String manipulation | |
Defined in header | |
strcpystrcpy_s (C11) | copies one string to another (function) |
strncpystrncpy_s (C11) | copies a certain amount of characters from one string to another (function) |
strcatstrcat_s (C11) | concatenates two strings (function) |
strncatstrncat_s (C11) | concatenates a certain amount of characters of two strings (function) |
strxfrm | transform a string so that strcmp would produce the same result as strcoll (function) |
String examination | |
Defined in header | |
strlenstrnlen_s (C11) | returns the length of a given string (function) |
strcmp | compares two strings (function) |
strncmp | compares a certain amount of characters of two strings (function) |
strcoll | compares two strings in accordance to the current locale (function) |
strchr | finds the first occurrence of a character (function) |
strrchr | finds the last occurrence of a character (function) |
strspn | returns the length of the maximum initial segment that consists of only the characters found in another byte string (function) |
strcspn | returns the length of the maximum initial segment that consists of only the characters not found in another byte string (function) |
strpbrk | finds the first location of any character in one string, in another string (function) |
strstr | finds the first occurrence of a substring of characters (function) |
strtokstrtok_s (C11) | finds the next token in a byte string (function) |
Character array manipulation | |
Defined in header | |
memchr | searches an array for the first occurrence of a character (function) |
memcmp | compares two buffers (function) |
memsetmemset_s (C11) | fills a buffer with a character (function) |
memcpymemcpy_s (C11) | copies one buffer to another (function) |
memmovememmove_s (C11) | moves one buffer to another (function) |
Miscellaneous | |
Defined in header | |
strerrorstrerror_sstrerrorlen_s (C11)(C11) | returns a text version of a given error code (function) |