Defined in header <stdlib.h> int system( const char *command ); Calls the host environment's command processor with command parameter. Returns implementation-defined value (usually the value that the invoked program returns). If command is NULL pointer, checks if host environment has a command processor and returns nonzero value only if it the command processor exists. Parameters command - character string identifying the command to be run in the command processor.

Defined in header <stdio.h> int fclose( FILE *stream ); Closes the given file stream. Any unwritten buffered data are flushed to the OS. Any unread buffered data are discarded. Whether or not the operation succeeds, the stream is no longer associated with a file, and the buffer allocated by setbuf or setvbuf, if any, is also disassociated and deallocated if automatic allocation was used. Parameters stream - the file stream to close Return value ​0​ on success,

Defined in header <stdarg.h> void va_end( va_list ap ); The va_end macro performs cleanup for an ap object initialized by a call to va_start or va_copy. va_end may modify ap so that it is no longer usable. If there is no corresponding call to va_start or va_copy, or if va_end is not called before a function that calls va_start or va_copy returns, the behavior is undefined. Parameters ap - an instance of the va_list type to clean up Expanded value (none). Ref

Defined in header <complex.h> float cimagf( float complex z ); (1) (since C99) double cimag( double complex z ); (2) (since C99) long double cimagl( long double complex z ); (3) (since C99) Defined in header <tgmath.h> #define cimag( z ) (4) (since C99) 1-3) Returns the imaginary part of z. 4) Type-generic macro: if z has type long double complex, long double imaginary, or long double, cimagl is called. If z has type float complex

Defined in header <stdlib.h> int atoi( const char *str ); long atol( const char *str ); long long atoll( const char *str ); (since C99) Interprets an integer value in a byte string pointed to by str. Discards any whitespace characters until the first non-whitespace character is found, then takes as many characters as possible to form a valid integer number representation and converts them to an integer value. The valid integer value consists of the fo

Defined in header <wctype.h> wctype_t wctype( const char* str ); (since C95) Constructs a value of type wctype_t that describes a LC_CTYPE category of wide character classification. It may be one of the standard classification categories, or a locale-specific category, such as "jkanji". Parameters str - C string holding the name of the desired category The following values of str are supported in all C locales: value of str effect "alnum" identifies the ca

Defined in header <wchar.h> wchar_t *wmemchr( const wchar_t *ptr, wchar_t ch, size_t count ); (since C95) Locates the first occurrence of wide character ch in the initial count wide characters of the wide character array or integer array of compatible type, pointed to by ptr. If count is zero, the function returns a null pointer. Parameters ptr - pointer to the wide character array to be examined ch - wide character to search for count - number of wide c

Defined in header <string.h> size_t strcspn( const char *dest, const char *src ); Returns the length of the maximum initial segment of the null-terminated byte string pointed to by dest, that consists of only the characters not found in the null-terminated byte string pointed to by src. The behavior is undefined if either dest or src is not a pointer to a null-terminated byte string. Parameters dest - pointer to the null-terminated byte string to be analyzed src

Defined in header <stdlib.h> int mbtowc( wchar_t *pwc, const char *s, size_t n ) (until C99) int mbtowc( wchar_t *restrict pwc, const char *restrict s, size_t n ) (since C99) Converts a multibyte character whose first byte is pointed to by s to a wide character, written to *pwc if pwc is not null. If s is a null pointer, resets the global conversion state and determines whether shift sequences are used. Notes Each call to mbtowc updates the intern

Defined in header <threads.h> int mtx_trylock( mtx_t *mutex ); (since C11) Tries to lock the mutex pointed to by mutex without blocking. Returns immediately if the mutex is already locked. Prior calls to mtx_unlock on the same mutex synchronize-with this operation (if this operation succeeds), and all lock/unlock operations on any given mutex form a single total order (similar to the modification order of an atomic). Parameters mutex - pointer to the mutex to lock