Pre-Defined C++ Functions (C++ Reserved Words0

cctype (ctype.h)

header

Character handling functions

This header declares a set of functions to classify and transform individual characters.

All these functions take as parameter the int equivalent of one character and return an int, that can either be another character or a value representing a boolean value: an int value of 0 means false, and an int value different from 0 represents true.

There are two sets of functions:

First a set of classifying functions that check whether the character passed as parameter belongs to a certain category. These are:

isalnum

Check if character is alphanumeric (function)

isalpha

Check if character is alphabetic (function)

iscntrl

Check if character is a control character (function)

isdigit

Check if character is decimal digit (function)

isgraph

Check if character has graphical representation (function)

islower

Check if character is lowercase letter (function)

isprint

Check if character is printable (function)

ispunct

Check if character is a punctuation character (function)

isspace

Check if character is a white-space (function )

isupper

Check if character is uppercase letter (function)

isxdigit

Check if character is hexadecimal digit (function)

And secondly, two functions to convert between letter cases:

tolower

Convert uppercase letter to lowercase (function)

toupper

Convert lowercase letter to uppercase (function)

For the first set, here is a map of how the original 127-character ASCII set is considered by each function (an x indicates that the function returns true on that character)

cmath (math.h)

header

C numerics library

cmath declares a set of functions to compute common mathematical operations and transformations:

Trigonometric functions:

cos	Compute cosine (function)

sin	Compute sine (function)

tan	Compute tangent (function)

acos	Compute arc cosine (function)

asin	Compute arc sine (function)

atan	Compute arc tangent (function)

atan2

Compute arc tangent with two parameters (function)

Hyperbolic functions:

cosh	Compute hyperbolic cosine (function)

sinh	Compute hyperbolic sine (function)

tanh	Compute hyperbolic tangent (function)

Exponential and logarithmic functions:

exp	Compute exponential function (function)

frexp

Get significand and exponent (function)

ldexp

Generate number from significand and exponent (function)

log	Compute natural logarithm (function)

log10

Compute common logarithm (function)

modf	Break into fractional and integral parts (function)

Power functions

pow	Raise to power (function)

sqrt	Compute square root (function)

Rounding, absolute value and remainder functions:

ceil	Round up value (function)

fabs	Compute absolute value (function)

floor

Round down value (function)

fmod	Compute remainder of division (function)

csignal (signal.h)

C library to handle signals

Some running environments use signals to inform running processes of certain events. These events may be related to errors performed by the program code, like a wrong arithmetical operation or to exceptional situations, such as a request to interrupt the program.

Signals generally represent situations where the program has either been requested to terminate or an unrecoverable error has happened, therefore handling a signal allows for either perform pre-termination cleanup operations or try to recover from the error in some way.

Not all running environments are required to generate automatic signals in the cases for which they are designed in the standard C library, and some other environments not only generate these but also many more specific signals. But in any case, all signals generated explicitly with a call to function raise are delivered to its corresponding signal handler.

The C header signal.h includes the following functions:

signal

Set function to handle signal (function )

raise

Generates a signal (function)

It also declares the following type:

sig_atomic_t

Integral type (type)

And several macro contant values: SIGABRT, SIGILL, SIGSEGV, SIG_DFL, SIG_IGN, SIGFPE, SIGINT, SIGTERM and SIG_ERROR (explained in signal).

cstdlib (stdlib.h)

header

C Standard General Utilities Library

This header defines several general purpose functions, including dynamic memory management, random number generation, communication with the environment, integer arthmetics, searching, sorting and converting.

Functions

String conversion:

atof	Convert string to double (function)

atoi	Convert string to integer (function)

atol	Convert string to long integer (function)

strtod

Convert string to double (function)

strtol

Convert string to long integer (function )

strtoul

Convert string to unsigned long integer (function )

Pseudo-random sequence generation:

rand	Generate random number (function)

srand

Initialize random number generator (functions)

Dynamic memory management:

calloc

Allocate space for array in memory (function)

free	Deallocate space in memory (function)

malloc

Allocate memory block (function)

realloc

Reallocate memory block (function)

Environment:

abort

Abort current process (function)

atexit

Set function to be executed on exit (function)

exit	Terminate calling process (function)

getenv

Get environment string (function)

system

Execute system command (function )

Searching and sorting:

bsearch

Binary search in array (function )

qsort

Sort elements of array (function)

Integer arithmethics:

abs	Absolute value (function)

div	Integral division (function)

labs	Absolute value (function)

ldiv	Integral division (function)

Multibyte characters:

mblen

Get length of multibyte character (function)

mbtowc

Convert multibyte character to wide character (function)

wctomb

Convert wide character to multibyte character (function)

Multibyte strings:

mbstowcs

Convert multibyte string to wide-character string (function)

wcstombs

Convert wide-character string to multibyte string (function)

Macros

EXIT_FAILURE

Failure termination code (macro)

EXIT_SUCCESS

Success termination code (macro)

MB_CUR_MAX

Maximum size of multibyte characters (macro)

NULL	Null pointer (macro)

RAND_MAX

Maximum value returned by rand (macro)

Types

div	Integral division (function)

ldiv	Integral division (function)

size_t

Unsigned integral type (type)

cstring (string.h)

header

C Strings

This header file defines several functions to manipulate C strings and arrays.

Functions

Copying:

memcpy

Copy block of memory (function)

memmove

Move block of memory (function )

strcpy

Copy string (function)

strncpy

Copy characters from string (function)

Concatenation:

strcat

Concatenate strings (function)

strncat

Append characters from string (function)

Comparison:

memcmp

Compare two blocks of memory (function)

strcmp

Compare two strings (function )

strcoll

Compare two strings using locale (function)

strncmp

Compare characters of two strings (function)

strxfrm

Transform string using locale (function)

Searching:

memchr

Locate character in block of memory (function)

strchr

Locate first occurrence of character in string (function)

strcspn

Get span until character in string (function)

strpbrk

Locate character in string (function)

strrchr

Locate last occurrence of character in string (function)

strspn

Get span of character set in string (function)

strstr

Locate substring (function)

strtok

Split string into tokens (function)

Other:

memset

Fill block of memory (function)

strerror

Get pointer to error message string (function)

strlen

Get string length (function )

Macros

NULL	Null pointer (macro)

Types

size_t

Unsigned integral type (type)

ctime (time.h)

header

C Time Library

This header file contains definitions of functions to get and manipulate date and time information.

Functions

Time manipulation

clock

Clock program (function)

difftime

Return difference between two times (function)

mktime

Convert tm structure to time_t (function)

time	Get current time (function)

Conversion:

asctime

Convert tm structure to string (function)

ctime

Convert time_t value to string (function)

gmtime

Convert time_t to tm as UTC time (function )

localtime

Convert time_t to tm as local time (function)

strftime

Format time to string (function)

Macros

CLOCKS_PER_SEC

Clock ticks per second (macro)

NULL	Null pointer (macro)

types

clock_t

Clock type (type )

size_t

Unsigned integral type (type)

time_t

Time type (type)

struct tm

Time structure (type)