C compilation system

String, character, environment and memory routines

These are functions and macros that perform a variety of tasks:

string manipulation
character classification
character conversion
environment management
memory management

The following tables list functions and macros that perform the first three tasks.

``String operations'' lists string-handling functions that appear in string(S). Programs that use these functions should include the header file string.h.

String operations

strcat Append a copy of one string to the end of another.

strncat Append no more than a given amount of characters from one string to the end of another.

strcmp Compare two strings. Returns an integer less than, greater than, or equal to 0 to show that one is lexicographically less than, greater than, or equal to the other.

strncmp Compare no more than a given amount of characters from the two strings. Results are otherwise identical to strcmp.

strcpy Copy a string.

strncpy Copy a given amount of characters from one string to another. The destination string will be truncated if it is longer than the given amount of characters, or padded with null characters if it is shorter.

strdup Return a pointer to a newly allocated string that is a duplicate of a string pointed to.

strchr Return a pointer to the first occurrence of a character in a string, or a null pointer if the character is not in the string.

strrchr Return a pointer to the last occurrence of a character in a string, or a null pointer if the character is not in the string.

strlen Return the number of characters in a string.

strpbrk Return a pointer to the first occurrence in one string of any character from the second, or a null pointer if no character from the second occurs in the first.

strspn Return the length of the initial segment of one string that consists entirely of characters from the second string.

strcspn Return the length of the initial segment of one string that consists entirely of characters not from the second string.

strstr Return a pointer to the first occurrence of the second string in the first string, or a null pointer if the second string is not found.

strtok Break up the first string into a sequence of tokens, each of which is delimited by one or more characters from the second string. Return a pointer to the token, or a null pointer if no token is found.

``Classifying 8-bit character-coded integer values'' lists functions and macros that classify 8-bit character-coded integer values. These routines appear in toascii(S) and ctype(S). Programs that use these routines should include the header file ctype.h.

strcat	Append a copy of one string to the end of another.
strncat	Append no more than a given amount of characters from one string to the end of another.
strcmp	Compare two strings. Returns an integer less than, greater than, or equal to 0 to show that one is lexicographically less than, greater than, or equal to the other.
strncmp	Compare no more than a given amount of characters from the two strings. Results are otherwise identical to strcmp.
strcpy	Copy a string.
strncpy	Copy a given amount of characters from one string to another. The destination string will be truncated if it is longer than the given amount of characters, or padded with null characters if it is shorter.
strdup	Return a pointer to a newly allocated string that is a duplicate of a string pointed to.
strchr	Return a pointer to the first occurrence of a character in a string, or a null pointer if the character is not in the string.
strrchr	Return a pointer to the last occurrence of a character in a string, or a null pointer if the character is not in the string.
strlen	Return the number of characters in a string.
strpbrk	Return a pointer to the first occurrence in one string of any character from the second, or a null pointer if no character from the second occurs in the first.
strspn	Return the length of the initial segment of one string that consists entirely of characters from the second string.
strcspn	Return the length of the initial segment of one string that consists entirely of characters not from the second string.
strstr	Return a pointer to the first occurrence of the second string in the first string, or a null pointer if the second string is not found.
strtok	Break up the first string into a sequence of tokens, each of which is delimited by one or more characters from the second string. Return a pointer to the token, or a null pointer if no token is found.

Classifying 8-bit character-coded integer values

isalpha Is c a letter?

isupper Is c an uppercase letter?

islower Is c a lowercase letter?

isdigit Is c a digit [0-9]?

isxdigit Is c a hexadecimal digit [0-9], [A-F], or [a-f]?

isalnum Is c alphanumeric (a letter or digit)?

isspace Is c a space, horizontal tab, carriage return, new-line, vertical tab, or form-feed?

ispunct Is c a punctuation character (neither control nor alphanumeric)?

isprint Is c a printing character?

isgraph Same as isprint except false for a space.

iscntrl Is c a control character or a delete character?

isascii Is c an ASCII character?

toupper Change lowercase to uppercase.

_toupper Macro version of toupper.

tolower Change uppercase to lowercase.

_tolower Macro version of tolower.

toascii Turn off all bits that are not part of a standard ASCII character; intended for compatibility with other systems.

``Converting characters, integers, or strings'' lists functions and macros that are used to convert characters, integers, or strings from one representation to another. The left column contains the name that appears at the top of the manual page; the other names in the same row are related functions or macros described on the same manual page. Programs that use these routines should include the header file stdlib.h.

Converting characters, integers, or strings

a64l l64a Convert between long integer and base-64 ASCII string.

ecvt fcvt gcvt Convert floating point number (long double

ecvtl fcvtl number) to string.

gcvtl

l3tol ltol3 Convert between 3-byte packed integer and long integer.

strtod atof strtold Convert string to double-precision number.

strtol atol atoi Convert string to integer.

strtoul Convert string to unsigned long.

isalpha	Is c a letter?
isupper	Is c an uppercase letter?
islower	Is c a lowercase letter?
isdigit	Is c a digit [0-9]?
isxdigit	Is c a hexadecimal digit [0-9], [A-F], or [a-f]?
isalnum	Is c alphanumeric (a letter or digit)?
isspace	Is c a space, horizontal tab, carriage return, new-line, vertical tab, or form-feed?
ispunct	Is c a punctuation character (neither control nor alphanumeric)?
isprint	Is c a printing character?
isgraph	Same as isprint except false for a space.
iscntrl	Is c a control character or a delete character?
isascii	Is c an ASCII character?
toupper	Change lowercase to uppercase.
_toupper	Macro version of toupper.
tolower	Change uppercase to lowercase.
_tolower	Macro version of tolower.
toascii	Turn off all bits that are not part of a standard ASCII character; intended for compatibility with other systems.

a64l	l64a		Convert between long integer and base-64 ASCII string.
ecvt	fcvt	gcvt	Convert floating point number (long double
	ecvtl	fcvtl	number) to string.
		gcvtl
l3tol	ltol3		Convert between 3-byte packed integer and long integer.
strtod	atof	strtold	Convert string to double-precision number.
strtol	atol	atoi	Convert string to integer.
strtoul			Convert string to unsigned long.