Null-terminated byte strings

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', '\0'} is an NTBS holding the string "cat" in ASCII encoding.

Functions

Character classification
Defined in header <cctype>
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 (C++11)	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)

ASCII values (hex)		characters	iscntrl iswcntrl.	isprint iswprint.	isspace iswspace.	isblank iswblank.	isgraph iswgraph.	ispunct iswpunct.	isalnum iswalnum.	isalpha iswalpha.	isupper iswupper.	islower iswlower.	isdigit iswdigit.	isxdigit iswxdigit.
0 - 8	0x00-0x08	control codes (NUL, etc.)	≠0	0	0	0	0	0	0	0	0	0	0	0
9	0x09	tab (\t)	≠0	0	≠0	≠0	0	0	0	0	0	0	0	0
10 - 13	0x0A-0x0D	whitespaces (\n,\v,\f,\r)	≠0	0	≠0	0	0	0	0	0	0	0	0	0
14 - 31	0x0E-0x1F	control codes	≠0	0	0	0	0	0	0	0	0	0	0	0
32	0x20	space	0	≠0	≠0	≠0	0	0	0	0	0	0	0	0
33 - 47	0x21-0x2F	!"#$%&'()*+,-./	0	≠0	0	0	≠0	≠0	0	0	0	0	0	0
48 - 57	0x30-0x39	0123456789	0	≠0	0	0	≠0	0	≠0	0	0	0	≠0	≠0
58 - 64	0x3a-0x40	:;<=>?@	0	≠0	0	0	≠0	≠0	0	0	0	0	0	0
65 - 70	0x41-0x46	ABCDEF	0	≠0	0	0	≠0	0	≠0	≠0	≠0	0	0	≠0
71 - 90	0x47-0x5A	GHIJKLMNOPQRSTUVWXYZ	0	≠0	0	0	≠0	0	≠0	≠0	≠0	0	0	0
91 - 96	0x5B-0x60	[\]^_`	0	≠0	0	0	≠0	≠0	0	0	0	0	0	0
97 -102	0x61-0x66	abcdef	0	≠0	0	0	≠0	0	≠0	≠0	0	≠0	0	≠0
103-122	0x67-0x7A	ghijklmnopqrstuvwxyz	0	≠0	0	0	≠0	0	≠0	≠0	0	≠0	0	0
123-126	0x7B-0x7E	{|}~	0	≠0	0	0	≠0	≠0	0	0	0	0	0	0
127	0x7F	backspace character (DEL)	≠0	0	0	0	0	0	0	0	0	0	0	0

Conversions to numeric formats
Defined in header <cstdlib>
atof	converts a byte string to a floating point value (function)
atoiatolatoll	converts a byte string to an integer value (function)
strtolstrtoll	converts a byte string to an integer value (function)
strtoul strtoull	converts a byte string to an unsigned integer value (function)
strtofstrtodstrtold	converts a byte string to a floating point value (function)
Defined in header <cinttypes>
strtoimaxstrtoumax (C++11)(C++11)	converts a byte string to std::intmax_t or std::uintmax_t (function)
String manipulation
Defined in header <cstring>
strcpy	copies one string to another (function)
strncpy	copies a certain amount of characters from one string to another (function)
strcat	concatenates two strings (function)
strncat	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 <cstring>
strlen	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 from a set of separators (function)
strstr	finds the first occurrence of a substring of characters (function)
strtok	finds the next token in a byte string (function)
Character array manipulation
Defined in header <cstring>
memchr	searches an array for the first occurrence of a character (function)
memcmp	compares two buffers (function)
memset	fills a buffer with a character (function)
memcpy	copies one buffer to another (function)
memmove	moves one buffer to another (function)
Miscellaneous
Defined in header <cstring>
strerror	returns a text version of a given error code (function)

See also

C documentation for Null-terminated byte strings