C language function finishing Daquan three (F-G)

Function Name: ecvt
Function: converts a floating point number to a string.
Usage: char ecvt (double value, int ndigit, int * decpt, int * sign );
Program example:
# Include
# Include
# Include
Int main (void)
{
Char * string;
Double value;
Int dec, sign;
Int ndig = 10;
Clrscr ();
Values = 9.876;
String = ecvt (value, ndig, & dec, & sign );
Printf ("string = % s dec = % d
Sign = % d ", string, dec, sign );
Value =-123.45;
Ndig = 15;
String = ecvt (value, ndig, & dec, & sign );
Printf ("string = % s dec = % d sign = % d ",
String, dec, sign );

Value = 0.6789e5;/* scientific
Notation */
Ndig = 5;
String = ecvt (value, ndig, & dec, & sign );
Printf ("string = % s dec = % d
Sign = % d ", string, dec, sign );
Return 0;
}

Function Name: ellipse
Skill: draw an ellipse
Usage: void far ellipse (int x, int y, int stangle, int endangle,
Int xradius, int yradius );
Program example:
# Include
# Include
# Include
# Include
Int main (void)
{
/* Request auto detection */
Int gdriver = DETECT, gmode, errorcode;
Int midx, midy;
Int stangle = 0, endangle = 360;
Int xradius = 100, yradius = 50;
/* Initialize graphics, local variables */
Initgraph (& gdriver, & gmode ,"");
/* Read result of initialization */
Errorcode = graphresult ();
If (errorcode! = GrOk)
/* An error occurred */
{
Printf ("Graphics error: % s ",
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 ellipse */
Ellipse (midx, midy, stangle, endangle,
Xradius, yradius );
/* Clean up */
Getch ();
Closegraph ();
Return 0;
}

Function Name: enable
Function: Enable hardware interruption
Usage: void enable (void );
Program example:
/*** NOTE:
This is an interrupt service routine. You can NOT compile this program
With Test Stack Overflow turned on and get an executable file which will
Operate correctly.
*/
# Include
# Include
# Include
/* The clock tick interrupt */
# Define INTR 0X1C
Void interrupt (* oldhandler) (void );
Int count = 0;
Void interrupt handler (void)
{
/*
Disable interrupts during the handling of the interrupt
*/
Disable ();
/* Increase the global counter */
Count;
/*
Re enable interrupts at the end of the handler
*/
Enable ();
/* Call the old routine */
Oldhandler ();
}
Int main (void)
{
/* Save the old interrupt vector */
Oldhandler = getvect (INTR );
/* Install the new interrupt handler */
Setvect (INTR, handler );
/* Loop until the counter exceeds 20 */
While (count <20)
Printf ("count is % d", count );
/* Reset the old interrupt handler */
Setvect (INTR, oldhandler );
Return 0;
}

Function Name: eof
Function: End of detection File
Usage: int eof (int * handle );
Program example:
# Include
# Include
# Include
# Include
# Include
Int main (void)
{
Int handle;
Char msg [] = "This is a test ";
Char ch;
/* Create a file */
Handle = open ("DUMMY. FIL ",
O_CREAT | O_RDWR,
S_IREAD | S_IWRITE );
/* Write some data to the file */
Write (handle, msg, strlen (msg ));
/* Seek to the beginning of the file */
Lseek (handle, 0L, SEEK_SET );
/*
Reads chars from the file until hit EOF
*/
Do
{
Read (handle, & ch, 1 );
Printf ("% c", ch );
} While (! Eof (handle ));
Close (handle );
Return 0;
}

Function Name: exec...
Functions: load and run functions of other programs
Usage: int execl (char * pathname, char * arg0, arg1,..., argn, NULL );
Int execle (char * pathname, char * arg0, arg1,..., argn, NULL,
Char * envp []);
Int execlp (char * pathname, char * arg0, arg1,..., NULL );
Int execple (char * pathname, char * arg0, arg1,..., NULL,
Char * envp []);
Int execv (char * pathname, char * argv []);
Int execve (char * pathname, char * argv [], char * envp []);
Int execvp (char * pathname, char * argv []);
Int execvpe (char * pathname, char * argv [], char * envp []);
Program example:
/* Execv example */
# Include
# Include
# Include
Void main (int argc, char * argv [])
{
Int I;
Printf ("Command line arguments :");
For (I = 0; I
Printf ("[-]: % s", I, argv [I]);
Printf ("About to exec child with arg1 arg2 ...");
Execv ("CHILD. EXE", argv );
Perror ("exec error ");
Exit (1 );
}

Function Name: exit
Function: Terminate the program
Usage: void exit (int status );
Program example:
# Include
# Include
# Include
Int main (void)
{
Int status;
Printf ("Enter either 1 or 2 ");
Status = getch ();
/* Sets DOS errorlevel */
Exit (status-'0 ');
/* Note: this line is never reached */
Return 0;
}

Function Name: gcvt

Function: converts a floating point to a string.

Usage: char * gcvt (double value, int ndigit, char * buf );

Program example:

#include
#include
int main(void)
{
char str[25];
double num;
int sig = 5; /* significant digits */
/* a regular number */
num = 9.876;
gcvt(num, sig, str);
printf("string = %s", str);
/* a negative number */
num = -123.4567;
gcvt(num, sig, str);
printf("string = %s", str);
/* scientific notation */
num = 0.678e5;
gcvt(num, sig, str);
printf("string = %s", str);
return(0);
}

Function Name: geninterrupt

Power: generate a Soft Interrupt

Usage: void geninterrupt (int intr_num );

Program example:

#include
#include
/* function prototype */
void writechar(char ch);
int main(void)
{
clrscr();
gotoxy(80,25);
writechar(‘*‘);
getch();
return 0;
}
/*
outputs a character at the current cursor
position using the video BIOS to avoid the
scrolling of the screen when writing to
location (80,25).
*/
void writechar(char ch)
{
struct text_info ti;
/* grab current text settings */
gettextinfo(&ti);
/* interrupt 0x10 sub-function 9 */
_AH = 9;
/* character to be output */
_AL = ch;
_BH = 0; /* video page */
_BL = ti.attribute; /* video attribute */
_CX = 1; /* repetition factor */
geninterrupt(0x10); /* output the char */
}




Function Name: getarccoords

Power: get the coordinates of the last called arc

Usage: void far getarccoords (struct arccoordstype far * arccoords );

Program example:

#include
#include
#include
#include
int main(void)
{
/* request auto detection */
int gdriver = DETECT, gmode, errorcode;
struct arccoordstype arcinfo;
int midx, midy;
int stangle = 45, endangle = 270;
char sstr[80], estr[80];
/* initialize graphics and local variables */
initgraph(&gdriver, &gmode, "");
/* read result of initialization */
errorcode = graphresult();
/* an error occurred */
if (errorcode != grOk)
{
printf("Graphics error: %s",
grapherrormsg(errorcode));
printf("Press any key to halt:");
getch();
/* terminate with an error code */
exit(1);
}
midx = getmaxx() / 2;
midy = getmaxy() / 2;
/* draw arc and get coordinates */
setcolor(getmaxcolor());
arc(midx, mi