Defined in header <ctype.h> int isalnum( int ch ); Checks if the given character is an alphanumeric character as classified by the current C locale. In the default locale, the following characters are alphanumeric: digits (0123456789) uppercase letters (ABCDEFGHIJKLMNOPQRSTUVWXYZ) lowercase letters (abcdefghijklmnopqrstuvwxyz) The behavior is undefined if the value of ch is not representable as unsigned char and is not equal to EOF. Parameters ch - character

Specifies that the function does not return to its point of invocation. Syntax _Noreturn function_declaration (since C11) Explanation The _Noreturn keyword appears in a function declaration and specifies that the function does not return by executing the return statement or by reaching the end of the function body (it may return by executing longjmp). If the function declared _Noreturn returns, the behavior is undefined. A compiler diagnostic is recommended if this can be detected

An object whose identifier is declared with the storage-class specifier _Thread_local (since C11) has thread storage duration. Its lifetime is the entire execution of the thread for which it is created, and its stored value is initialized when the thread is started. There is a distinct object per thread, and use of the declared name in an expression refers to the object associated with the thread evaluating the expression. The result of attempting to indirectly access an object with thread stor

Defined in header <signal.h> typedef /* unspecified */ sig_atomic_t; An integer type which can be accessed as an atomic entity even in the presence of asynchronous interrupts made by signals. Example #include <signal.h> #include <stdio.h> volatile sig_atomic_t gSignalStatus = 0; void signal_handler(int signal) { gSignalStatus = signal; } int main(void) { /* Install a signal handler. */ signal(SIGINT, signal_handler); printf("SignalVa

Defined in header <math.h> float tanhf( float arg ); (1) (since C99) double tanh( double arg ); (2) long double tanhl( long double arg ); (3) (since C99) Defined in header <tgmath.h> #define tanh( arg ) (4) (since C99) 1-3) Computes the hyperbolic tangent of arg. 4) Type-generic macro: If the argument has type long double, tanhl is called. Otherwise, if the argument has integer type or the type double, tanh is called. Otherwise, t

Defined in header <stdlib.h> #define EXIT_SUCCESS /*implementation defined*/ #define EXIT_FAILURE /*implementation defined*/ The EXIT_SUCCESS and EXIT_FAILURE macros expand into integral expressions that can be used as arguments to the exit function (and, therefore, as the values to return from the main function), and indicate program execution status. Constant Explanation EXIT_SUCCESS successful execution of a program EXIT_FAILURE unsuccessful execution of

Defined in header <time.h> int timespec_get( struct timespec *ts, int base) (since C11) #define TIME_UTC /* implementation-defined */ (since C11) 1) Modifies the timespec object pointed to by ts to hold the current calendar time in the time base base. 2) Expands to a value suitable for use as the base argument of timespec_get Other macro constants beginning with TIME_ may be provided by the implementation to indicate additional time bases. If base is TIME_UTC, then

Defined in header <wchar.h> int fwide( FILE *stream, int mode ); (since C95) If mode > 0, attempts to make stream wide-oriented. If mode < 0, attempts to make stream byte-oriented. If mode==0, only queries the current orientation of the stream. If the orientation of the stream has already been decided (by executing output or by an earlier call to fwide), this function does nothing. Parameters stream - pointer to the C I/O stream to modify or query mode -

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

/* unspecified */ va_list; va_list is a complete object type suitable for holding the information needed by the macros va_start, va_copy, va_arg, and va_end. If a va_list instance is created, passed to another function, and used via va_arg in that function, then any subsequent use in the calling function should be preceded by a call to va_end. It is legal to pass a pointer to a va_list object to another function and then use that object after the function returns. References C11 sta