Linux C function library reference manual

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Linux C function library reference manual

Chapter 2 character test functions
Isalnum (test whether the character is an English letter or number)
Isalpha (test whether the character is an English letter)
Isascii (test whether the character is an ASCII character)
Isblank (test whether the character is a space character)
Iscntrl (test whether the character is an ASCII control character)
Isdigit (test whether the character is Arabic numerals)
Isgraph (test whether the character is printable)
Islower (test whether the character is a lowercase English letter)
Isprint (test whether the character is printable)
Isspace (test whether the character is a space character)
Ispunct (test whether the character is a punctuation or special symbol)
Isupper (test whether the character is an uppercase English letter)
Isxdigit (test whether the character is a hexadecimal number)
Chapter 2 data conversion functions
Atof (converts a string to a float number) 1
Atoi (convert a string to an integer)
Atol (convert string to integer)
ECVT (convert the float number to a string, and take 19 as rounding)
Fcvt (convert the float number to a string, and rounding 20 out)
Gcvt (convert float to string, and rounding 21) Chapter 1 memory configuration functions
Alloca (configure memory space)
BRK (change the range of data bytes)
Calloc (configure memory space)
Free (release the previously configured memory)
Getpagesize (obtain the memory paging size)
Malloc (configure memory space)
MMAP (Create memory ing)
Munmap (remove memory ing)
Realloc (change the configured memory space)
Sbrk (increase the data space available for the Program)
Chapter 1 time functions
Asctime (represents the time and date in string format)
Clock (obtain the CPU usage time of the process)
Ctime (Representation of time and date in string format)
Difftime (computing time gap)
Ftime (get the current time and date)
Gettimeofday (get current time)
Gmtime (get the current time and date)
Localtime (obtain the current local time and date)
Mktime (the number of seconds after the time structure data is converted)
Settimeofday (set the current time)
Strftime (format Date and Time)
Time (obtain the current time)
Tzset (set the time zone for time conversion)
Chapter 2 string processing functions
Bcmp (memory content comparison)
Bcopy (copy memory content)
Bzero (clear all memory content to zero)
FFs (find the first value in an integer to be a real digit)
Index (find the first specified character in the string)
Memccpy (copy memory content)
Memchr (find a specific character in a memory range)
Memcmp (memory content comparison)
Memcpy (copy memory content)
Memfrob (memory region encoding)
Memmove (copy memory content)
Memset (enter a certain value for a piece of memory space)
Rindex (find the last occurrence of the specified character in the string)
Strcasecmp (case-insensitive strings are ignored)
Strcat (connect two strings)
Strchr (find the first occurrence of the specified character in the string)
Strcmp (comparison string)
Strcoll (use the character arrangement order of the current region to compare strings)
Strcpy (copy string)
Strcspn (returns the number of consecutive characters in the string that do not contain the content of the specified string)
Strdup (copy string)
Strfry)
Strlen (returns the string length)
Strncasecmp (case-insensitive comparison string ignored)
Strncat (connect two strings)
Strncmp (comparison string)
Strncpy (copy string)
Strpbrk (find the first occurrence of the specified character in the string)
Strrchr (find the last occurrence of the specified character in the string)
Strspns (returns the number of consecutive characters in the string that do not match the specified string content)
Strstr (search for the specified string in a string)
Strtok (split string)
Chapter 2 mathematical functions
ABS (calculate the absolute value of an integer)
ACOs (returns the arccosine function value)
Asin (returns the arcsin function value)
Atan (returns the arc tangent function value)
Atan2 (obtain the arctangent function value)
Ceil (minimum integer value not less than the parameter)
Cos (cosine function value)
Cosh (returns the hyperbolic cosine function value)
Div (the quotient and remainder after the division of Two integer values)
Exp (computing index)
FABS (calculate the absolute value of floating point type)
Frexp (float data is divided into base data and indexes)
Hypot)
Labs (calculate the absolute value of a long integer)
Ldexp (calculate the power of 2)
Ldiv (obtain the quotient and remainder after division of two long integers)
Log (calculate the logarithm value based on E)
Log10 (calculate the base-10 logarithm value)
MODF (splits floating point numbers into integers and decimals)
Pow (calculate power)
Sin (sine function value)
Sinh (returns the hyperbolic sine function value)
SQRT (calculate the square root value)
Tan (returns the tangent function value)
Tanh (returns the hyperbolic tangent function value)
Chapter 4 user and group functions
Cuserid (get user account name)
Endgrent (close group files)
Endpwent (close Password File)
Endutent (disable the utmp file)
Fgetgrent (reads the Group format from the specified file)
Fgetpwent (read the password format from the specified file)
Getegid (get valid group ID)
Geteuid (get valid user identification code)
Getgid (obtain the real group ID)
Getgrent (obtains account data from group files)
Getgrgid (get the data of the specified GID from the group file)
Getgrnan (obtains data of the specified group from the group file)
Getgroups (get group code)
Getlogin (get the Login User Account name)
Getpw (obtain the password file data of the specified user)
Getpwent (obtains account data from the password file)
Getpwnam (obtains the data of the specified account from the password file)
Getpwuid (obtain the data of the specified uid from the password file)
Getuid (get real user identification code)
Getutent (obtains account logon data from the utmp file)
Getutid (find a specific record from the utmp file)
Getutline (find a specific record from the utmp file)
Initgroups (initialization group list)
Logwtmp (record the logon data to the wtmp file)
Pututline (write utmp records to files)
Setegid (set a valid group ID)
Seteuid (set valid user identification code)
Setfsgid (set the group ID of the file system)
Setfsuid (set the user ID of the file system)
Setgid (set a real group ID)
Setgrent (reads group data from group files from the beginning)
Setgroups (set group code)
Setpwent (read account data from password file from scratch)
Setregid (set real and valid group ID)
Setreuid (set real and valid user identification code)
Setuid (set real user identification code)
Setutent (read the login data in the utmp/file from the beginning)
Updwtmp (record the logon data to the wtmp file)
Utmpname (set the utmp file path)
Chapter 2 data encryption functions
Crypt (password or data encoding)
Getpass (get a password)
Chapter 2 data structure functions
Bsearch)
Hcreate (create a hash table)
Hdestory (delete hash table)
Hsearch)
Insque (add a project to the queue)
Lfind (linear search)
Lsearch)
Qsort (sort arrays by quick sorting)
Rremque (delete a project from the queue)
Tdelete (delete data from binary tree)
Tfind)
Tsearch (Binary Tree)
Twalk (visit Binary Tree)
Chapter 1 random number Functions
Drand48 (generate a positive floating point random number)
Erand48 (generate a positive floating point random number)
Initstate (create an array of random number states)
Jrand48 (generates a long integer random number)
Lcong48 (set the seed of the random number of the 48-bit operation)
Lrand48 (generate a positive long integer random number)
Mrand48 (generate a long integer random number)
Nrand48 (generate a positive long integer random number)
Rand (Random Number Generation)
Random (Random Number Generation)
Seed48 (seed48 random number seed)
Setstate (create a random number status array)
Srand (set Random Seed)
Srand48 (set the seed of the random number of the 48-bit operation)
Srandom (set Random Seed)
Chapter 2 elementary I/O functions
Close (close the file)
Creat (create a file)
DUP (copy file description)
Dup2 (copy file description)
Fcntl (File description operations)
Flock (lock file or unlock)
Fsync (write buffer data back to disk)
Lseek (read/write location of mobile files)
Mkstemp (create a unique temporary file)
Open (open a file)
Read (read data from opened files)
Sync (write buffer data back to disk)
Write (write data into an opened file)
Chapter 1 Standard I/O functions
Clearerr (error flag for clearing file streams)
Fclose (close file)
Fdopen (convert file description to file pointer)
Feof (check whether the file stream has read the end Of the file)
Fflush (update buffer)
Fgetc (one character read from the file)
Fgetpos (get the reading location of the file stream)
Fgets (read a string from the file)
Fileno (returns the file description used by the file Stream)
Fopen (open a file)
Fputc (write a specified character to the file Stream)
Fputs (write a specified string into the file)
Fread (reads data from a file Stream)
Freopen (open a file)
Fseek (read/write location of a mobile file Stream)
Fsetpos (read/write location of a mobile file Stream)
Ftell (get the reading location of the file stream)
Fwrite (write data to a file Stream)
GETC (one character read from the file)
Getchar (reads one character from the standard input device)
Gets (reads a string from the standard input device)
Mktemp (generate a unique temporary file name)
Putc (write a specified character to the file)
Putchar (write specified characters to the standard output device)
Puts (write the specified string to the standard output device)
Rewind (resetting the file stream's read/write position to start with the file)
Setbuf (set the buffer of the file Stream)
Setbuffer (set the buffer of the file Stream)
Setlinebuf (set the file stream as a linear buffer)
Setvbuf (set the buffer of the file Stream)
Tmpfile (create a temporary file)
Ungetc (write a specified character back to the file Stream)
Chapter 4 Process and Process Control
Abort (terminate the process in an abnormal way)
Assert (if the test condition is not true, terminate the process)
Atexit (set the function called before the program ends normally)
Execl (Execution file)
Execle (Execution file)
Execlp (find and execute files from PATH environment variables)
Execv (Execution file)
Execve (Execution file)
Execvp (Execution file)
Exit (process terminated normally)
_ Exit (End Process execution)
Fork (create a new process)
Getpgid (obtain the process group ID)
Getpgrp (obtain the Process Group Identifier)
Getpid (obtain the process identifier)
Getppid (obtain the process identifier of the parent process)
Getpriority (get the program process execution priority)
Longjmp (jump to the stack environment saved by setjmp)
Nice (change process priority)
On_exit (set the function called before the program ends normally)
Ptrace (process tracing)
Setjmp (Save the current stack environment)
Setpgid (set the process Group Identifier)
Setpgrp (set the process Group Identifier)
Setpriority (set program process execution priority)
Siglongjmp (jump to the stack environment saved by the original sigsetjmp)
Sigsetjmp (Save the current stack environment)
System (execute shell command)
Wait (waiting for the sub-process to be interrupted or terminated)
Waitpid (waiting for sub-process interruption or termination)
Chapter 4 formatting the input/output functions
Fprintf (format the output data to a file)
Fscanf (Format String input)
Printf (format output data)
Scanf (Format String input)
Snprintf (format string copy)
Sprintf (format string copy)
Sscanf (Format String input)
Vfprintf (format the output data to a file)
Vfcanf (Format String input)
Vprintf (format output data)
Vscanf (Format String input)
Vsnprintf (format string copy)
Vsprintf (format string copy)
Vsscanf (Format String input)
Chapter 4 file and directory Functions
Access)
Alphasort (sort the directory structure alphabetically)
Chdir (change the current working directory)
Chmod (change file permissions)
Chown (change the file owner)
Chroot (Change root directory)
Closedir (close directory)
Fchdir (change the current working directory)
Fchmod (change file permissions)
Fchown (change the file owner)
Fstat (obtained by the file description)
Ftruncate (change file size)
FTW (traverse directory tree)
Get_current_dir_name (get the current working directory)
Getcwd (get the current working directory)
Getwd (get the current working directory)
Lchown (change the file owner)
Link)
Lstat (obtained by the file description)
NFTW (traversing the directory tree)
Opendir (Open Directory)
Readdir (read directory)
Readlink)
Realpath (convert relative directory paths to absolute paths)
Remove (delete file)
Rename (change the file name or location)
Rewinddir (resetting the starting position of the read directory)
Scandir (read specific directory data)
Seekdir (set the location of the next read directory)
Stat (Get File status)
Symlink)
Telldir (get the reading location of the Directory Stream)
Truncate (change file size)
Umask (set the permission mask when creating a new file)
Unlink (delete file)
Utime (modify the file access time and change time)
Utimes (modify file access time and change time)
Chapter 4 Signal Functions
Alarm)
Kill (send a signal to a specified process)
Pause (pause the process until the signal appears)
Psignal (list signal descriptions and specified strings)
Raise (send a signal to the current process)
Sigaction (query or set the signal processing method)
Sigaddset (add a signal to the signal set)
Sigdelset (delete a signal from the signal set)
Sigemptyset (initialize Signal Set)
Sigfillset (add all signals to the signal set)
Sigismember (test whether a signal has been added to the signal set)
Signal (set Signal Processing Method)
Sigpause (pause until the signal arrives)
Sigpending (query signals shelved)
Sigprocmask (query or set the signal mask)
Sigsuspend (pause until the signal arrives)
Sleep (pause the process for a period of time)
Isdigit (test whether the character is Arabic numerals)
Chapter 1 error handling functions
Ferror (check whether an error occurs in the file Stream)
Perror (print the error cause string)
Streror (returns the description string of the error cause)
Chapter 1 MPs queue Functions
Mkfifo (create a named pipe)
Pclose (disable pipeline I/O)
Pipe (pipeline creation)
Popen (create pipeline I/O)
Chapter 2 soket Functions
Accept (accept socket connections)
BIND (locate the socket)
Connect (establish socket connection)
Endprotoent (end network protocol data READING)
Endservent (end Network Service Data Reading)
Gethostbyaddr (obtain network data from IP addresses)
Gethostbyname (obtain network data by host name)
Getprotobyname (obtain protocol data by network protocol name)
Getprotobynumber (obtain protocol data by network protocol number)
Getprotoent (obtain network protocol data)
Getservbyname (obtain network service data by name)
Getservbyport (obtain network service data by port number)
Getservent (obtain the data of the host network service)
Getsockopt (obtain the socket status)
Herror (print the network error cause string)
Hstrerror (returns the description string of the network error cause)
Htonl (converts 32-bit host characters to the network character sequence)
Htons (converts the 16-bit host Character Sequence to the network character sequence)
Inet_addr (convert the network address to a binary number of the Network)
Inet_aton (convert the network address to a binary number of the Network)
Inet_ntoa (convert the binary number of the network to the network address)
Listen (waiting for connection)
Ntohl (converts 32-bit network character sequence to host Character Sequence)
Ntohs (converts the 16-bit network character sequence to the host Character Sequence)
Recv (receiving data through socket)
Recvfrom (receiving data through socket)
Recvmsg (receiving data through socket)
Send (transmit data through socket)
Sendmsg (transmits data through socket)
Sendto (transmits data through socket)
Setprotoent (open the network protocol data file)
Setservent (open the data file of the host network service)
Setsockopt (set socket status)
Shutdown (terminate socket communication)
Socket (establish a socket communication)
Chapter 2 Process Communication (IPC) Functions
Ftok (convert the file path and plan code to systemcvipckey)
Msgctl (controls the operation of information queues)
Msgget (create an information queue)
Msgrcv (read information from the information queue)
Msgsnd (send information to the information queue)
Semctl (control signal queue operations)
Semget (configure the signal Queue)
Semop (Signal Processing)
Shmat (attach shared memory)
Shmctl (controls shared memory operations)
Shmdt (detach shared memory)
Shmget (configure shared memory)
Chapter 1 record functions
Closelog (disable information record)
Openlog (prepare for information record)
Syslog (records information to system log files)
Chapter 2 Environment Variable Functions
Getenv (get environment variable content)
Putenv (change or add environment variables)
Setenv (change or add environment variables)
Unsetenv (clear environment variable content)
Chapter 1 Regular Expressions
Regcomp (compile a regular expression string)
Regerror (error cause for obtaining regular expression search)
Regexec (search for regular expressions)
Regfree (releases the memory used by regular expressions)
Chapter 2 dynamic Functions
Dlclose (close the dynamic function library file)
Dlerror (Dynamic Function error handling)
Dlopen (open the dynamic function library file)
Dlsym (search for dynamic functions from shared objects)
Chapter 2 Other Functions
Getopt (analyze command line parameters)
Isatty (determine whether the file description is a terminal)
Select (I/O multi-work mechanism)
Ttyname (return the name of a terminal)