midx = getmaxx() / 2; 
midy = getmaxy() / 2; 
setcolor(getmaxcolor()); 

/* draw ellipse */ 
ellipse(midx, midy, stangle, endangle, 
xradius, yradius); 

/* clean up */ 
getch(); 
closegraph(); 
return 0; 
} 



函數名: enable 
功 能: 開放硬件中斷 
用 法: void enable(void); 
程序例: 

/* ** 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 <stdio.h> 
#include <dos.h> 
#include <conio.h> 

/* 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\n",count); 

/* reset the old interrupt handler */ 
setvect(INTR, oldhandler); 

return 0; 
} 



函數名: eof 
功 能: 檢測文件結束 
用 法: int eof(int *handle); 
程序例: 

#include <sys\stat.h> 
#include <string.h> 
#include <stdio.h> 
#include <fcntl.h> 
#include <io.h> 

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; 
} 



函數名: exec... 
功 能: 裝入并運行其它程序的函數 
用 法: 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[]); 
程序例: 

/* execv example */ 
#include <process.h> 
#include <stdio.h> 
#include <errno.h> 

void main(int argc, char *argv[]) 
{ 
int i; 

printf("Command line arguments:\n"); 
for (i=0; i<argc; i++) 
printf("[%2d] : %s\n", i, argv[i]); 

printf("About to exec child with arg1 arg2 ...\n"); 
execv("CHILD.EXE", argv); 

perror("exec error"); 

exit(1); 
} 



函數名: exit 
功 能: 終止程序 
用 法: void exit(int status); 
程序例: 

#include <stdlib.h> 
#include <conio.h> 
#include <stdio.h> 

int main(void) 
{ 
int status; 

printf("Enter either 1 or 2\n"); 
status = getch(); 
/* Sets DOS errorlevel */ 
exit(status - '0'); 

/* Note: this line is never reached */ 
return 0; 
} 



函數名: exp 
功 能: 指數函數 
用 法: double exp(double x); 
程序例: 

#include <stdio.h> 
#include <math.h> 

int main(void) 
{ 
double result; 
double x = 4.0; 

result = exp(x); 
printf("'e' raised to the power \ 
of %lf (e ^ %lf) = %lf\n", 
x, x, result); 

return 0; 
}  

--------------------------------------------------------------------------------
 

 
 
C語言庫函數(F類字母) 
AiY.CN 收集整理 (2001-07-27 15:00:00) 
函數名: fabs 
功 能: 返回浮點數的絕對值 
用 法: double fabs(double x); 
程序例: 
#include <stdio.h> 
#include <math.h> 

int main(void) 
{ 
float number = -1234.0; 

printf("number: %f absolute value: %f\n", 
number, fabs(number)); 
return 0; 
} 




函數名: farcalloc 
功 能: 從遠堆棧中申請空間 
用 法: void far *farcalloc(unsigned long units, unsigned ling unitsz); 
程序例: 
#include <stdio.h> 
#include <alloc.h> 
#include <string.h> 
#include <dos.h> 

int main(void) 
{ 
char far *fptr; 
char *str = "Hello"; 

/* allocate memory for the far pointer */ 
fptr = farcalloc(10, sizeof(char)); 

/* copy "Hello" into allocated memory */ 
/* 
Note: movedata is used because you 
might be in a small data model, in 
which case a normal string copy routine 
can not be used since it assumes the 
pointer size is near. 
*/ 
movedata(FP_SEG(str), FP_OFF(str), 
FP_SEG(fptr), FP_OFF(fptr), 
strlen(str)); 

/* display string (note the F modifier) */ 
printf("Far string is: %Fs\n", fptr); 

/* free the memory */ 
farfree(fptr); 

return 0; 
} 




函數名: farcoreleft 
功 能: 返回遠堆中未作用存儲區大小 
用 法: long farcoreleft(void); 
程序例: 

#include <stdio.h> 
#include <alloc.h> 

int main(void) 
{ 
printf("The difference between the\ 
highest allocated block in the\ 
far\n"); 
printf("heap and the top of the far heap\ 
is: %lu bytes\n", farcoreleft()); 

return 0; 
} 




函數名: farfree 
功 能: 從遠堆中釋放一塊 
用 法: void farfree(void); 
程序例: 

#include <stdio.h> 
#include <alloc.h> 
#include <string.h> 
#include <dos.h> 

int main(void) 
{ 
char far *fptr; 
char *str = "Hello"; 

/* allocate memory for the far pointer */ 
fptr = farcalloc(10, sizeof(char)); 

/* copy "Hello" into allocated memory */ 
/* 
Note: movedata is used because you might be in a small data model, 
in which case a normal string copy routine can't be used since it 
assumes the pointer size is near. 
*/ 
movedata(FP_SEG(str), FP_OFF(str), 
FP_SEG(fptr), FP_OFF(fptr), 
strlen(str)); 

/* display string (note the F modifier) */ 
printf("Far string is: %Fs\n", fptr); 

/* free the memory */ 
farfree(fptr); 

return 0; 
} 




函數名: farmalloc 
功 能: 從遠堆中分配存儲塊 
用 法: void far *farmalloc(unsigned long size); 
程序例: 

#include <stdio.h> 
#include <alloc.h> 
#include <string.h> 
#include <dos.h> 

int main(void) 
{ 
char far *fptr; 
char *str = "Hello"; 

/* allocate memory for the far pointer */ 
fptr = farmalloc(10); 

/* copy "Hello" into allocated memory */ 
/* 
Note: movedata is used because we might 
be in a small data model, in which case 
a normal string copy routine can not be 
used since it assumes the pointer size 
is near. 
*/ 
movedata(FP_SEG(str), FP_OFF(str), 
FP_SEG(fptr), FP_OFF(fptr), 
strlen(str)); 

/* display string (note the F modifier) */ 
printf("Far string is: %Fs\n", fptr); 

/* free the memory */ 
farfree(fptr); 

return 0; 
} 




函數名: farrealloc 
功 能: 調整遠堆中的分配塊 
用 法: void far *farrealloc(void far *block, unsigned long newsize); 
程序例: 

#include <stdio.h> 
#include <alloc.h> 

int main(void) 
{ 
char far *fptr; 

fptr = farmalloc(10); 
printf("First address: %Fp\n", fptr); 
fptr = farrealloc(fptr,20); 
printf("New address : %Fp\n", fptr); 
farfree(fptr); 
return 0; 
} 



函數名: fclose 
功 能: 關閉一個流 
用 法: int fclose(FILE *stream); 
程序例: 

#include <string.h> 
#include <stdio.h> 

int main(void) 
{ 
FILE *fp; 
char buf[11] = "0123456789"; 

/* create a file containing 10 bytes */ 
fp = fopen("DUMMY.FIL", "w"); 
fwrite(&buf, strlen(buf), 1, fp); 

/* close the file */ 
fclose(fp); 
return 0; 
} 




函數名: fcloseall 
功 能: 關閉打開流 
用 法: int fcloseall(void); 
程序例: 

#include <stdio.h> 

int main(void) 
{ 
int streams_closed; 

/* open two streams */ 
fopen("DUMMY.ONE", "w"); 
fopen("DUMMY.TWO", "w"); 

/* close the open streams */ 
streams_closed = fcloseall(); 

if (streams_closed == EOF) 
/* issue an error message */ 
perror("Error"); 
else 
/* print result of fcloseall() function */ 
printf("%d streams were closed.\n", streams_closed); 

return 0; 
} 



函數名: fcvt 
功 能: 把一個浮點數轉換為字符串 
用 法: char *fcvt(double value, int ndigit, int *decpt, int *sign); 
程序例: 

#include <stdlib.h> 
#include <stdio.h> 
#include <conio.h> 

int main(void) 
{ 
char *string; 
double value; 
int dec, sign; 
int ndig = 10; 

clrscr(); 
value = 9.876; 
string = ecvt(value, ndig, &dec, &sign); 
printf("string = %s dec = %d \ 
sign = %d\n", string, dec, sign); 

value = -123.45; 
ndig= 15; 
string = ecvt(value,ndig,&dec,&sign); 
printf("string = %s dec = %d sign = %d\n", 
string, dec, sign); 


value = 0.6789e5; /* scientific 
notation */ 
ndig = 5; 
string = ecvt(value,ndig,&dec,&sign); 
printf("string = %s dec = %d\ 
sign = %d\n", string, dec, sign); 

return 0; 
} 




函數名: fdopen 
功 能: 把流與一個文件句柄相接 
用 法: FILE *fdopen(int handle, char *type); 
程序例: 

#include <sys\stat.h> 
#include <stdio.h> 
#include <fcntl.h> 
#include <io.h> 

int main(void) 
{ 
int handle; 
FILE *stream; 

/* open a file */ 
handle = open("DUMMY.FIL", O_CREAT, 
S_IREAD | S_IWRITE); 

/* now turn the handle into a stream */ 
stream = fdopen(handle, "w"); 

if (stream == NULL) 
printf("fdopen failed\n"); 
else 
{ 
fprintf(stream, "Hello world\n"); 
fclose(stream); 
} 
return 0; 
} 



函數名: feof 
功 能: 檢測流上的文件結束符 
用 法: int feof(FILE *stream); 
程序例: 

#include <stdio.h> 

int main(void) 
{ 
FILE *stream; 

/* open a file for reading */ 
stream = fopen("DUMMY.FIL", "r"); 

/* read a character from the file */ 
fgetc(stream); 

/* check for EOF */ 
if (feof(stream)) 
printf("We have reached end-of-file\n"); 

/* close the file */ 
fclose(stream); 
return 0; 
} 



函數名: ferror 
功 能: 檢測流上的錯誤 
用 法: int ferror(FILE *stream); 
程序例: 

#include <stdio.h> 

int main(void) 
{ 
FILE *stream; 

/* open a file for writing */ 
stream = fopen("DUMMY.FIL", "w"); 

/* force an error condition by attempting to read */ 
(void) getc(stream); 

if (ferror(stream)) /* test for an error on the stream */ 
{ 
/* display an error message */ 
printf("Error reading from DUMMY.FIL\n"); 

/* reset the error and EOF indicators */ 
clearerr(stream); 
} 

fclose(stream); 
return 0; 
} 




函數名: fflush 
功 能: 清除一個流 
用 法: int fflush(FILE *stream); 
程序例: 

#include <string.h> 
#include <stdio.h> 
#include <conio.h> 
#include <io.h> 

void flush(FILE *stream); 

int main(void) 
{ 
FILE *stream; 
char msg[] = "This is a test"; 

/* create a file */ 
stream = fopen("DUMMY.FIL", "w"); 

/* write some data to the file */ 
fwrite(msg, strlen(msg), 1, stream); 

clrscr(); 
printf("Press any key to flush\ 
DUMMY.FIL:"); 
getch(); 

/* flush the data to DUMMY.FIL without\ 
closing it */ 
flush(stream); 

printf("\nFile was flushed, Press any key\ 
to quit:"); 
getch(); 
return 0; 
} 

void flush(FILE *stream) 
{ 
int duphandle; 

/* flush the stream's internal buffer */ 
fflush(stream); 

/* make a duplicate file handle */ 
duphandle = dup(fileno(stream)); 

/* close the duplicate handle to flush\ 
the DOS buffer */ 
close(duphandle); 
} 




函數名: fgetc 
功 能: 從流中讀取字符 
用 法: int fgetc(FILE *stream); 
程序例: 

#include <string.h> 
#include <stdio.h> 
#include <conio.h> 

int main(void) 
{ 
FILE *stream; 
char string[] = "This is a test"; 
char ch; 

/* open a file for update */ 
stream = fopen("DUMMY.FIL", "w+"); 

/* write a string into the file */ 
fwrite(string, strlen(string), 1, stream); 

/* seek to the beginning of the file */ 
fseek(stream, 0, SEEK_SET); 

do 
{ 
/* read a char from the file */ 
ch = fgetc(stream); 

/* display the character */ 
putch(ch); 
} while (ch != EOF); 

fclose(stream); 
return 0; 
} 




函數名: fgetchar 
功 能: 從流中讀取字符 
用 法: int fgetchar(void); 
程序例: 

#include <stdio.h> 

int main(void) 
{ 
char ch; 

/* prompt the user for input */ 
printf("Enter a character followed by \ 
<Enter>: "); 

/* read the character from stdin */ 
ch = fgetchar(); 

/* display what was read */ 
printf("The character read is: '%c'\n", 
ch); 
return 0; 
} 




函數名: fgetpos 
功 能: 取得當前文件的句柄 
用 法: int fgetpos(FILE *stream); 
程序例: 

#include <string.h> 
#include <stdio.h> 

int main(void) 
{ 
FILE *stream; 
char string[] = "This is a test"; 
fpos_t filepos; 

/* open a file for update */ 
stream = fopen("DUMMY.FIL", "w+"); 

/* write a string into the file */ 
fwrite(string, strlen(string), 1, stream); 

/* report the file pointer position */ 
fgetpos(stream, &filepos); 
printf("The file pointer is at byte\ 
%ld\n", filepos); 

fclose(stream); 
return 0; 
} 




函數名: fgets 
功 能: 從流中讀取一字符串 
用 法: char *fgets(char *string, int n, FILE *stream); 
程序例: 

#include <string.h> 
#include <stdio.h> 

int main(void) 
{ 
FILE *stream; 
char string[] = "This is a test"; 
char msg[20]; 

/* open a file for update */ 
stream = fopen("DUMMY.FIL", "w+"); 

/* write a string into the file */ 
fwrite(string, strlen(string), 1, stream); 

/* seek to the start of the file */ 
fseek(stream, 0, SEEK_SET); 

/* read a string from the file */ 
fgets(msg, strlen(string)+1, stream); 

/* display the string */ 
printf("%s", msg);