C language library function Daquan (letter a) --- instructions for use)

C language library function Daquan (letter a) --- instructions for use (conversion) -- Linux general technology-Linux programming and kernel information, the following is read details. Function Name: abort
Function: terminates a process abnormally.
Usage: void abort (void );
Program example:
# Include
# Include
Int main (void)
{
Printf ("Calling abort () \ n ");
Abort ();
Return 0;/* This is never reached */
}



Function Name: abs
Function: Calculate the absolute value of an integer.
Usage: int abs (int I );
Program example:
# Include
# Include

Int main (void)
{
Int number =-1234;

Printf ("number: % d absolute value: % d \ n", number, abs (number ));
Return 0;
}



Function Name: absread, abswirte
Functions: Read and Write Data in absolute disk sectors
Usage: int absread (int drive, int nsects, int sectno, void * buffer );
Int abswrite (int drive, int nsects, in tsectno, void * buffer );
Program example:
/* Absread example */

# Include
# Include
# Include
# Include

Int main (void)
{
Int I, strt, ch_out, sector;
Char buf [512];

Printf ("Insert a diskette into drive A and press any key \ n ");
Getch ();
Sector = 0;
If (absread (0, 1, sector, & buf )! = 0)
{
Perror ("Disk problem ");
Exit (1 );
}
Printf ("Read OK \ n ");
Strt = 3;
For (I = 0; I <80; I ++)
{
Ch_out = buf [strt + I];
Putchar (ch_out );
}
Printf ("\ n ");
Return (0 );
}




Function Name: access
Skill: determine the object access permission
Usage: int access (const char * filename, int amode );
Program example:
# Include
# Include

Int file_exists (char * filename );

Int main (void)
{
Printf ("Does NOTEXIST. FIL exist: % s \ n ",
File_exists ("NOTEXISTS. FIL ")? "YES": "NO ");
Return 0;
}

Int file_exists (char * filename)
{
Return (access (filename, 0) = 0 );
}


Function Name: acos
Function: arccosine Function
Usage: double acos (double x );
Program example:
# Include
# Include

Int main (void)
{
Double result;
Double x = 0.5;

Result = acos (x );
Printf ("The arc cosine of % lf is % lf \ n", x, result );
Return 0;
}



Function Name: allocmem
Function: allocate DOS storage segments
Usage: int allocmem (unsigned size, unsigned * seg );
Program example:
# Include
# Include
# Include

Int main (void)
{
Unsigned int size, segp;
Int stat;

Size = 64;/* (64x16) = 1024 bytes */
Stat = allocmem (size, & segp );
If (stat =-1)
Printf ("Allocated memory at segment: % x \ n", segp );
Else
Printf ("Failed: maximum number of paragraphs available is % u \ n ",
Stat );

Return 0;
}



Function Name: arc
Power: draw an arc
Usage: void far arc (int x, int y, int stangle, int endangle, int radius );
Program example:
# Include
# Include
# Include
# Include

Int main (void)
{
/* Request auto detection */
Int gdriver = DETECT, gmode, errorcode;
Int midx, midy;
Int stangle = 45, endangle = 135;
Int radius = 100;

/* Initialize graphics and local variables */
Initgraph (& gdriver, & gmode ,"");

/* Read result of initialization */
Errorcode = graphresult ();/* an error occurred */
If (errorcode! = GrOk)
{
Printf ("Graphics error: % s \ n", grapherrormsg (errorcode ));
Printf ("Press any key to halt :");
Getch ();

Exit (1);/* terminate with an error code */
}

Midx = getmaxx ()/2;
Midy = getmaxy ()/2;
Setcolor (getmaxcolor ());

/* Draw arc */
Arc (midx, midy, stangle, endangle, radius );

/* Clean up */
Getch ();
Closegraph ();
Return 0;
}



Function Name: asctime
Function: Convert the date and time into ASCII codes.
Usage: char * asctime (const struct tm * tblock );
Program example:
# Include
# Include
# Include

Int main (void)
{
Struct tm t;
Char str [80];

/* Sample loading of tm structure */

T. tm_sec = 1;/* Seconds */
T. tm_min = 30;/* Minutes */
T. tm_hour = 9;/* Hour */
T. tm_mday = 22;/* Day of the Month */
T. tm_mon = 11;/* Month */
T. tm_year = 56;/* Year-does not include century */
T. tm_wday = 4;/* Day of the week */
T. tm_yday = 0;/* Does not show in asctime */
T. tm_isdst = 0;/* Is Daylight SavTime; does not show in asctime */

/* Converts structure to null terminated
String */

Strcpy (str, asctime (& t ));
Printf ("% s \ n", str );

Return 0;
}




Function Name: asin
Power: arcsin Function
Usage: double asin (double x );
Program example:
# Include
# Include

Int main (void)
{
Double result;
Double x = 0.5;

Result = asin (x );
Printf ("The arc sin of % lf is % lf \ n", x, result );
Return (0 );
}




Function Name: assert
Skill: test a condition and possibly terminate the program
Usage: void assert (int test );
Program example:
# Include
# Include
# Include

Struct ITEM {
Int key;
Int value;
};

/* Add item to list, make sure list is not null */
Void additem (struct ITEM * itemptr ){
Assert (itemptr! = NULL );
/* Add item to list */
}

Int main (void)
{
Additem (NULL );
Return 0;
}




Function Name: atan
Function: returns the arc tangent function.
Usage: double atan (double x );
Program example:
# Include
# Include

Int main (void)
{
Double result;
Double x = 0.5;

Result = atan (x );
Printf ("The arc tangent of % lf is % lf \ n", x, result );
Return (0 );
}



Function Name: atan2
Function: Calculate the arc tangent value of Y/X.
Usage: double atan2 (double y, double x );
Program example:
# Include
# Include

Int main (void)
{
Double result;
Double x = 90.0, y = 45.0;

Result = atan2 (y, x );
Printf ("The arc tangent ratio of % lf is % lf \ n", (y/x), result );
Return 0;
}



Function Name: atexit
Function: register the termination function.
Usage: int atexit (atexit_t func );
Program example:
# Include
# Include

Void exit_fn1 (void)
{
Printf ("Exit function #1 called \ n ");
}

Void exit_fn2 (void)
{
Printf ("Exit function #2 called \ n ");
}

Int main (void)
{
/* Post exit function #1 */
Atexit (exit_fn1 );
/* Post exit function #2 */
Atexit (exit_fn2 );
Return 0;
}


Function Name: atof
Function: converts a string to a floating point number.
Usage: double atof (const char * nptr );
Program example:
# Include
# Include

Int main (void)
{
Float f;
Char * str = "12345.67 ";

F = atof (str );
Printf ("string = % s float = % f \ n", str, f );
Return 0;
}



Function Name: atoi
Function: converts a string to an integer.
Usage: int atoi (const char * nptr );
Program example:
# Include
# Include

Int main (void)
{
Int n;
Char * str = "12345.67 ";

N = atoi (str );
Printf ("string = % s integer = % d \ n", str, n );
Return 0;
}



Function Name: atol
Function: converts a string to an integer.
Usage: long atol (const char * nptr );
Program example:

# Include
# Include

Int main (void)
{
Long l;
Char * str = "98765432 ";

L = atol (lstr );
Printf ("string = % s integer = % ld \ n", str, l );
Return (0 );
}