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Page 891 Part III:Library FunctionsPage 892 IntroDESCRIPTION This chapter describes all the library functions, excluding the library functions described in Part 2, which implement system calls. The various function groups are identified by a letter that is appended to the chapter number:
AUTHORS Look at the header of the manual page for the author(s) and copyright conditions. Note that these can be different from page to page! Linux, 13 December 1995 abortabort—Causes abnormal program termination SYNOPSIS #include <stdlib.h> void abort(void); DESCRIPTION The abort() function causes abnormal program termination unless the signal SIGABORT is caught and the signal handler does not return. If the abort() function causes program termination, all open streams are closed and flushed. If the SIGABORT function is blocked or ignored, the abort() function will still override it. RETURN VALUE The abort() function never returns. CONFORMS TO SVID 3, POSIX, BSD 4.3, ISO 9899 SEE ALSO sigaction(2), exit(3) GNU, 12 April 1993 absabs—Computes the absolute value of an integer Page 893 SYNOPSIS #include <stdlib.h> int abs(int j); DESCRIPTION The abs() function computes the absolute value of the integer argument j. RETURN VALUE Returns the absolute value of the integer argument. CONFORMS TO SVID 3, POSIX, BSD 4.3, ISO 9899 NOTES Trying to take the absolute value of the most negative integer is not defined. SEE ALSO ceil(3), floor(3), fabs(3), labs(3), rint(3) GNU, 6 June 1993 acosacos—Arc cosine function SYNOPSIS #include <math.h> double acos(double x); DESCRIPTION The acos() function calculates the arc cosine of x; that is the value whose cosine is x. If x falls outside the range _1 to 1, acos() fails and errno is set. RETURN VALUE The acos() function returns the arc cosine in radians; the value is mathematically defined to be between 0 and pi (inclusive). ERRORS EDOM x is out of range. CONFORMS TO SVID 3, POSIX, BSD 4.3, ISO 9899 SEE ALSO asin(3), atan(3), atan2(3), cos(3), sin(3), tan(3) 8 June 1993 acoshacosh—Inverse hyperbolic cosine function Page 894 SYNOPSIS #include <math.h> double acosh(double x); DESCRIPTION The acosh() function calculates the inverse hyperbolic cosine of x; that is the value whose hyperbolic cosine is x. If x is less than 1.0, acosh() returns not-a-number (NaN), and errno is set. ERRORS
CONFORMS TO SVID 3, POSIX, BSD 4.3, ISO 9899 SEE ALSO asinh(3), atanh(3), cosh(3), sinh(3), tanh(3) 13 June 1993 allocaalloca—Memory allocator SYNOPSIS #include <stdlib.h> void *alloca( size_t size); DESCRIPTION The alloca function allocates size bytes of space in the stack frame of the caller. This temporary space is automatically freed on return. RETURN VALUES The alloca function returns a pointer to the beginning of the allocated space. If the allocation fails, a NULL pointer is returned. CONFORMS TO There is evidence that the alloca function appeared in 32v, pwb, pwb.2, 3bsd, and 4bsd. There is a man page for it in BSD 4.3. Linux uses the GNU version. BUGS The alloca function is machine dependent. SEE ALSO brk(2), pagesize(2), calloc(3), malloc(3), realloc(3) GNU, 29 November 1993 asinasin—Arc sine function Page 895 SYNOPSIS #include <math.h> double asin(double x); DESCRIPTION The asin() function calculates the arc sine of x, which is the value whose sine is x. If x falls outside the range _1 to 1, asin() fails and errno is set. RETURN VALUE The asin() function returns the arc sine in radians, and the value is mathematically defined to be between -PI/2 and PI/2 (inclusive). ERRORS
CONFORMS TO SVID 3, POSIX, BSD 4.3, ISO 9899 SEE ALSO acos(3), atan(3), atan2(3), cos(3), sin(3), tan(3) 8 June 1993 asinhasinh—Inverse hyperbolic sine function SYNOPSIS #include <math.h> double asinh(double x); DESCRIPTION The asinh() function calculates the inverse hyperbolic sine of x—that is, the value whose hyperbolic sine is x. CONFORMS TO SVID 3, POSIX, BSD 4.3, ISO 9899 SEE ALSO acosh(3), atanh(3), cosh(3), sinh(3), tanh(3) 13 June 1993 assertassert—Abort the program if assertion is false SYNOPSIS #include <assert.h> void assert (int expression); Page 896 DESCRIPTION assert() prints an error message to standard output and terminates the program by calling abort() if expression is false (that is, evaluates to 0). This only happens when the macro NDEBUG is undefined. RETURN VALUE No value is returned. CONFORMS TO ISO9899 (ANSI C) BUGS assert() is implemented as a macro; if the expression tested has side effects, program behavior will be different depending on whether NDEBUG is defined. This may create Heisenbugs, which go away when debugging is turned on. SEE ALSO exit(3), abort(3) GNU, 4 April 1993 atanatan—Arc tangent function SYNOPSIS #include <math.h> double atan(double x); DESCRIPTION The atan() function calculates the arc tangent of x—that is, the value whose tangent is x. RETURN VALUE The atan() function returns the arc tangent in radians, and the value is mathematically defined to be between -PI/2 and PI/2 (inclusive). CONFORMS TO SVID 3, POSIX, BSD 4.3, ISO 9899 SEE ALSO acos(3), asin(3), atan2(3), cos(3), sin(3), tan(3) 8 June 1993 atan2atan2—Arc tangent function of two variables SYNOPSIS #include <math.h> double atan2(double y, double x); |
