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 <ctype.h> | |
|---|---|
| checks if a character is alphanumeric (function) | |
| checks if a character is alphabetic (function) | |
| checks if a character is lowercase (function) | |
| checks if a character is an uppercase character (function) | |
| checks if a character is a digit (function) | |
| checks if a character is a hexadecimal character (function) | |
| checks if a character is a control character (function) | |
| checks if a character is a graphical character (function) | |
| checks if a character is a space character (function) | |
| (C99) | checks if a character is a blank character (function) |
| checks if a character is a printing character (function) | |
| checks if a character is a punctuation character (function) | |
Character manipulation | |
| converts a character to lowercase (function) | |
| 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.
| ASCII values (hex) | characters | |||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| 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 <stdlib.h> | |
|---|---|
| converts a byte string to a floating point value (function) | |
| (C99) | converts a byte string to an integer value (function) |
| (C99) | converts a byte string to an integer value (function) |
| (C99) | converts a byte string to an unsigned integer value (function) |
| (C99)(C99) | converts a byte string to a floating point value (function) |
| Defined in header <inttypes.h> | |
| (C99)(C99) | converts a byte string to intmax_t or uintmax_t (function) |
String manipulation | |
| Defined in header <string.h> | |
| (C11) | copies one string to another (function) |
| (C11) | copies a certain amount of characters from one string to another (function) |
| (C11) | concatenates two strings (function) |
| (C11) | concatenates a certain amount of characters of two strings (function) |
| transform a string so that strcmp would produce the same result as strcoll (function) | |
String examination | |
| Defined in header <string.h> | |
| (C11) | returns the length of a given string (function) |
| compares two strings (function) | |
| compares a certain amount of characters of two strings (function) | |
| compares two strings in accordance to the current locale (function) | |
| finds the first occurrence of a character (function) | |
| finds the last occurrence of a character (function) | |
| returns the length of the maximum initial segment that consists of only the characters found in another byte string (function) | |
| returns the length of the maximum initial segment that consists of only the characters not found in another byte string (function) | |
| finds the first location of any character in one string, in another string (function) | |
| finds the first occurrence of a substring of characters (function) | |
| (C11) | finds the next token in a byte string (function) |
Character array manipulation | |
| Defined in header <string.h> | |
| searches an array for the first occurrence of a character (function) | |
| compares two buffers (function) | |
| (C11) | fills a buffer with a character (function) |
| (C11) | copies one buffer to another (function) |
| (C11) | moves one buffer to another (function) |
Miscellaneous | |
| Defined in header <string.h> | |
| (C11)(C11) | returns a text version of a given error code (function) |
References
- C11 standard (ISO/IEC 9899:2011):
- 7.4 Character handling <ctype.h> (p: 200-204)
- 7.8 Format conversion of integer types <inttypes.h> (p: 217-220)
- 7.22 General utilities <stdlib.h> (p: 340-360)
- 7.24 String handling <string.h> (p: 362-372)
- 7.31.2 Character handling <ctype.h> (p: 455)
- 7.31.5 Format conversion of integer types <inttypes.h> (p: 455)
- 7.31.12 General utilities <stdlib.h> (p: 456)
- 7.31.13 String handling <string.h> (p: 456)
- K.3.6 General utilities <stdlib.h> (p: 604=613)
- K.3.7 String handling <string.h> (p: 614-623)
- C99 standard (ISO/IEC 9899:1999):
- 7.4 Character handling <ctype.h> (p: 181-185)
- 7.8 Format conversion of integer types <inttypes.h> (p: 198-201)
- 7.20 General utilities <stdlib.h> (p: 306-324)
- 7.21 String handling <string.h> (p: 325-334)
- 7.26.2 Character handling <ctype.h> (p: 401)
- 7.26.4 Format conversion of integer types <inttypes.h> (p: 401)
- 7.26.10 General utilities <stdlib.h> (p: 402)
- 7.26.11 String handling <string.h> (p: 402)
- C89/C90 standard (ISO/IEC 9899:1990):
- 4.3 CHARACTER HANDLING <ctype.h>
- 4.10 GENERAL UTILITIES <stdlib.h>
- 4.11 STRING HANDLING <string.h>
- 4.13.2 Character handling <ctype.h>
- 4.13.7 General utilities <stdlib.h>
- 4.13.8 String handling <string.h>
See also
C++ documentation for Null-terminated byte strings |
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