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C mathematical function library
Character processing function

This category function is used to deal with single characters, including the category test of characters and the case conversion of characters.

Header file ctype.h

Function list

Detailed description of function category and function purpose

Is the character test alphanumeric?

Is that the letter isalpha?

Whether to control the character iscntrl.

Is it digital?

Can I display characters (except spaces)?

Can I display characters (including spaces)?

Is it a displayable character that is neither a space nor letters and numbers?

Whether this space is space or not.

Is the capital letter isupper?

Is the hexadecimal digit (0-9, A-F) character of 16 xdigital?

Character case conversion function is converted to uppercase letter toupper.

Convert to lowercase letter tolower

regionalization

Functions in this category are used to deal with language differences in different countries.

Header file local.h

Function list

Detailed description of function category and function purpose

Zone control zone setting setlocale

The number format convention queries the format conversion of the country's currency, date, time, etc.

mathematical function

This classification gives various mathematical calculation functions. It must be reminded that the data format in ANSI C standard does not conform to IEEE754 standard, but some C language compilers follow IEEE754 (for example, frinklin C5 1).

Header file math.h

Function list

Detailed description of function category and function purpose

Error condition handles domain error (the input parameter value of the function is not within the specified range)

Range error (the return value of the function is not within the specified range)

Trigonometric function anti-cosine function

Arc string asin

Inverse cheatan

Arctangent 2 atan2

Cosine cosine

Sine sine

Tangent tan

Hyperbolic function hyperbolic cosine cosine

Hyperbolic sine

Hyperbolic tangent function

Exponential and logarithmic exponential functions

Exponential decomposition function frexp

Product exponential function fdexp

natural logarithm

Logarithm 10, radix 10.

Floating-point decomposition function

Power function power function power

Square root function

Integer truncation, the lower bound of absolute value and remainder function is close to integer ceil.

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Find the upper bound near the lower bound of integer.

Find the remainder

This classification function is used to jump code directly between different basis functions. Header file setjmp.h io.h

Function list

Detailed description of function category and function purpose

Save the calling environment setjmp

Resume calling environment longjmp

Signal processing

This classification function is used to handle the abnormal situation during the execution of the program.

Header file signal

Function list

Detailed description of function category and function purpose

Designated signal processing function signal

Send a lifting signal.

Variable parameter processing

This kind of function is used to realize variable basis functions such as printf and scanf.

Header file stdarg.h

Function list

Detailed description of function category and function purpose

Variable parameter access macro variable parameter start macro va_start

Variable parameter ending macro va_end

The variable parameter access macro accesses the next variable parameter macro va_arg.

Input-output function

This classification is used to handle various input and output devices, including files and consoles, and various functions are realized in a "stream" way.

Header file stdio.h

Function list

Detailed description of function category and function purpose

Document function

Delete file removal

Modify file name rename

Generate temporary file name tmpfile

Get temporary file path tmpnam

File access closed. File closed.

Refresh buffer fflush

opening file

Connect existing stream pointers and new files to freopen.

Set disk buffer setbuf

Set disk buffer setvbuf

Format input and output functions print format fprintf

Format input fscanf

Format output (console) printf

Format input (console) scan f

Format the output to the buffer sprintf

Enter sscanf format from the buffer.

Print format vfprintf

Print format vprintf

Print format vsprintf

The character input and output function inputs the character fgetc.

String input fgets

Character output fputc

String output fputs

Character input (console)

Character input (console) getchar

String input (console) acquisition

Character output (console)

Character output (console) putchar

String output (console) puts

Characters are output to the header ungetc of the stream.

Direct input output direct stream read operation

Direct stream write operation fwrite

The file location function gets the file location fgetpos.

File location moving search

File location setting offset

Get file location ftell

File location reset zero reminder

Error handling function error clearing clearerr

End of file judgment

File error detection

Get the error prompt string perror

utility function

This classification gives some functions that cannot be classified according to the above, but are necessary for programming.

Header file standard library

Function list

Detailed description of function category and function purpose

The string conversion function converts a string into an integer atoi.

Converts a string to a long integer.

Converts a string to a floating-point number strtod

Converts a string to a long integer.

Converts a string to an unsigned long integer.

Pseudo-random sequence generation function generates random number rand

Sets the starting value srand of the random function.

Memory management function allocates memory calloc

deallocating memory

Memory allocation malloc

Reassigned memory

Abort (environmental communication termination procedure)

Exit the program execution and clear the environment variable atexit.

Exit program execution exit

Read environment parameter getenv

The program is suspended and another program system is temporarily executed.

Search and sort tool method of bisection (data must be sorted) search.

Quick sort qsort

Absolute value abs of integer operation function

discrepancy

Get the base quotient and remainder of division operation.

Find the absolute value of length and shape the bottom laboratory

Find the quotient and remainder ldiv of long shaping division

The multibyte character function gets the number of bytes of multibyte characters.

Gets the number of bytes of multibyte characters mbtowc.

Multibyte character conversion

The string operation of multibyte characters converts multibyte strings into integer arrays mbstowcs.

Converts a multibyte string into a character array mcstowbs.

String processing

This classification function is used to merge and compare strings.

Header file string.h

Function list

Detailed description of function category and function purpose

String Copy Block Copy (target and source storage cannot overlap) memcpy

Block copy (target and source storage can overlap) Memory movement

String replication

Copy strncpy by string length

strcat_s

Connect the string strncat by length

String comparison function block comparison memcmp

String comparison strcmp

String comparison (non-English characters)

Compare strncmp and string by length

String conversion strxfrm

Character and string lookup character lookup memory

Character search structure

String lookup strcspn

String lookup strpbrk

String lookup strspn

String lookup strstr

String decomposition string

Miscellaneous function string setting memory set

Error string mapping string error.

Find the string length strlen

Date and time function

This category provides time and date processing functions.

Header file time.h

Function list

Detailed description of function category and function purpose

The time operation function obtains the processor clock.

Get the time difference difftime

Set time mktime

Get time time

Time conversion function gets the time of ASCII code.

Gets the time ctime represented by a string.

Gets the time strftime in the specified format.

Future development direction of function library

This section is used to explain how various types of function libraries will develop in the future.

Detailed description of serial number library category header file

1 error handling error number h

2 character processing ctype.h

3 regionalized local.h

4 mathematical function math.h

5 signal processing signal

6 input and output stdio.h

7 utility stdlib.h

8 string processing string.h