Defined in header <string.h> char* strerror( int errnum ); (1) errno_t strerror_s( char *buf, rsize_t bufsz, errno_t errnum ); (2) (since C11) size_t strerrorlen_s( errno_t errnum ); (3) (since C11) 1) Returns a pointer to the textual description of the system error code errnum, identical to the description that would be printed by perror(). errnum is usually acquired from the errno variable, however the function accepts any value of type int. The contents of

Defined in header <math.h> float sqrtf( float arg ); (1) (since C99) double sqrt( double arg ); (2) long double sqrtl( long double arg ); (3) (since C99) Defined in header <tgmath.h> #define sqrt( arg ) (4) (since C99) 1-3) Computes square root of arg. 4) Type-generic macro: If arg has type long double, sqrtl is called. Otherwise, if arg has integer type or the type double, sqrt is called. Otherwise, sqrtf is called. If arg is com

Defined in header <math.h> float nanf( const char* arg ); (since C99) double nan( const char* arg ); (since C99) long double nanl( const char* arg ); (since C99) Converts the implementation-defined character string arg into the corresponding quiet NaN value, as if by calling strtod, strtof, or strtold, respectively, as follows: The call nan("string") is equivalent to the call strtod("NAN(string)", (char**)NULL);. The call nan("") is equivalent to the

Usage long type modifier

Defined in header <ctype.h> int tolower( int ch ); Converts the given character to lowercase according to the character conversion rules defined by the currently installed C locale. In the default "C" locale, the following uppercase letters ABCDEFGHIJKLMNOPQRSTUVWXYZ are replaced with respective lowercase letters abcdefghijklmnopqrstuvwxyz. Parameters ch - character to be converted. If the value of ch is not representable as unsigned char and does not equal EOF, the

Usage continue statement: as the declaration of the statement

Defined in header <complex.h> float cprojf( float complex z ); (1) (since C99) double cproj( double complex z ); (2) (since C99) long double cprojl( long double complex z ); (3) (since C99) Defined in header <tgmath.h> #define cproj( z ) (4) (since C99) 1-3) Computes the projection of z on the Riemann sphere. 4) Type-generic macro: if z has type long double complex, long double imaginary, or long double, cprojl is called. If z has

Defined in header <ctype.h> int isgraph( int ch ); Checks if the given character has a graphical representation, i.e. it is either a number (0123456789), an uppercase letter (ABCDEFGHIJKLMNOPQRSTUVWXYZ), a lowercase letter (abcdefghijklmnopqrstuvwxyz), or a punctuation character(!"#$%&'()*+,-./:;<=>?@[\]^_`{|}~), or any graphical character specific to the current C locale. The behavior is undefined if the value of ch is not representable as unsigned char and is no

Defined in header <stdlib.h> void qsort( void *ptr, size_t count, size_t size, int (*comp)(const void *, const void *) ); (1) errno_t qsort_s( void *ptr, rsize_t count, rsize_t size, int (*comp)(const void *, const void *, void *), void *context ); (2) (since C11) 1) Sorts the given array pointed to by ptr in ascending order. The array contains count elements of size bytes. Function pointed to by comp is used for object c

Defined in header <wctype.h> int iswdigit( wint_t ch ); (since C95) Checks if the given wide character corresponds (if narrowed) to one of the ten decimal digit characters 0123456789. Parameters ch - wide character Return value Non-zero value if the wide character is an numeric character, zero otherwise. Notes iswdigit and iswxdigit are the only standard wide character classification functions that are not affected by the currently installed C locale. Exa