During regular programming:
<stdio.h>: Provide standard input and output functions, such asprintf,scanf,fprintf,fscanfetc.
<stdlib.h>: Provides commonly used general functions, such as memory management functions (malloc,calloc,realloc,free), random number functions (rand,srand), string conversion functions (atoi,atof,itoa), etc.
<string.h>: Provide string processing functions, such as string copy function (strcpy,strncpy), string concatenation function (strcat,strncat), string comparison function (strcmp,strncmp), string search function (strchr,strstr), etc.
<math.h>: Provides mathematical functions, such as commonly used mathematical operation functions (sqrt,pow,sin,cos,logetc.) and mathematical constants (M_PI,M_Eetc.).
<ctype.h>: Provide character processing functions, such as character judgment functions (isalpha,isdigit,islower,isupperetc.), character conversion functions (tolower,toupper), etc.
<time.h>: Provide time and date related functions, such as get current time function (time), format time function (strftime), delay function (sleep), etc.
<stdbool.h>: Define Boolean types and constants (true,false), and provide related functions such asbool,true, and so on.false
These are just some common C standard libraries, there are many other widely used libraries, such as network programming libraries <net.h>, graphics libraries <graphics.h>, etc. According to different needs, you can choose the appropriate library to use the corresponding function.
Linux system programming
<stdio.h>: Provides standard input and output functions for reading and outputting data.printf(): Formatted output data to standard output.scanf(): Read formatted data from standard input.fopen():open a file.fclose(): Close the file.
<stdlib.h>: Functions that provide functions such as memory management, process control, and string conversion.malloc(): Allocate a memory space of the specified size.free(): Release the previously allocated memory space.exit(): Terminate program execution.atoi(): Converts a string to an integer.
<unistd.h>: Provides system call functions for creating processes, executing programs, and communicating through pipes.fork(): Create a new process.exec(): Execute a new program.pipe(): Create a pipeline.
<fcntl.h>: Provides file operation related functions for opening, reading and writing files.open():open a file.read(): Read data from a file.write(): Write data to the file.
<sys/types.h>: Defines system data types, such as process ID, file descriptor, etc.
<sys/stat.h>: Provides functions related to file status, such as obtaining file attributes, modifying file permissions, etc.stat(): Get the properties of the file.
<signal.h>: Provides signal processing related functions for capturing and processing signals.signal(): Set the signal processing function.kill(): Send a signal to the specified process.
<pthread.h>: Provides thread-related functions for creating and managing threads.pthread_create(): Create a new thread.pthread_join(): Wait for the end of the thread.
<netinet/in.h>: Provides network-related functions for creating and managing network connections.socket(): Create a socket.bind(): Bind the socket to a specific address and port.listen(): Listen to the specified socket.
<arpa/inet.h>: Provides a network address translation function for converting IP addresses and port numbers.inet_addr(): Convert an IP address in dotted decimal notation to a 32-bit integer in network byte order.inet_ntoa(): Convert a 32-bit integer in network byte order to an IP address in dotted decimal notation.
The functions in these header files can help developers implement various system-level functions, such as file operations, process management, and network communication. By calling these functions, you can easily interact with the operating system to complete the required functions.