The function ungetc () in Cthe function int ungetc (int char, file * stream) in the c library standard pushes the char character (an unsigned char) onto the stream given to the next character to be read.
The function perror () in Cthe function void perror (const char * str) in the c library standard prints a message describing the error to stderr. first, the printed string str is followed by a colon and then a space.
Calloc () function in Cthe function void * calloc (so-phan-tu, kich-co-phan-tu) allocates the requested memory and returns a pointer to it. the difference between malloc and calloc is: malloc does not set memory to 0 while calloc sets the allocated memory to 0.
Free () function in Cthe void free function (void * ptr) frees the previously allocated memory by a call to calloc, malloc, or realloc
The function atexit () in Cint atexit function (void (* func) (void)) calls function func when the program ends. you can register your end function (func function) wherever you like, but this function will be called at the end of the program.
The exit () function in Cthe void exit (int status) function immediately terminates the calling process. any file opened by the process is closed and any child process is inherited by the initial process and the parent process is sent a sigchild signal.
Function tmpfile () in Cfunction file * tmpfile (void) in standard c library create temporary files in wb + mode. the temporary file created will be automatically deleted when the stream is closed (fclose function) or when the program ends.
Function tmpnam () in Cthe function char * tmpnam (char * str) in the c library standard creates and returns a valid temporary file name (temp file) that did not exist before creation. if str is null, it returns the tmp file name.
Function fprintf () in Cthe int fprintf function (file * stream, const char * format, ...) in standard c library sends formatted output to a stream.
The function gets () in Cthe char * gets (char * str) function in standard c library reads a line from stdin and stores it inside the string pointed by str. it stops when the end-of-file or newline character is encountered (new line) is read.
Function vfprintf () in Cthe int vfprintf function (file * stream, const char * format, va_list arg) in the standard c library sends the formatted output to a stream using a parameter list.
The function vsprintf () in Cthe function int vsprintf (char * str, const char * format, va_list arg) in the standard c library sends the formatted output to a string string using a parameter list.
The function ungetc () in C
the function int ungetc (int char, file * stream) in the c library standard pushes the char character (an unsigned char) onto the stream given to the next character to be read.
