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<P>函數名: raise
<BR>功 能: 向正在執行的程序發送一個信號
<BR>用 法: int raise(int sig);
<BR>程序例:
<P>#include <signal.h>
<P>int main(void)
<BR>{
<BR> int a, b;
<P> a = 10;
<BR> b = 0;
<BR> if (b == 0)
<BR> /* preempt divide by zero error */
<BR> raise(SIGFPE);
<BR> a = a / b;
<BR> return 0;
<BR>}
<BR>
<BR>
<P>函數名: rand
<BR>功 能: 隨機數發生器
<BR>用 法: void rand(void);
<BR>程序例:
<P>#include <stdlib.h>
<BR>#include <stdio.h>
<P>int main(void)
<BR>{
<BR> int i;
<P> printf("Ten random numbers from 0 to 99\n\n");
<BR> for(i=0; i<10; i++)
<BR> printf("%d\n", rand() % 100);
<BR> return 0;
<BR>}
<BR>
<BR>
<P>函數名: randbrd
<BR>功 能: 隨機塊讀
<BR>用 法: int randbrd(struct fcb *fcbptr, int reccnt);
<BR>程序例:
<P>#include <process.h>
<BR>#include <string.h>
<BR>#include <stdio.h>
<BR>#include <dos.h>
<P>int main(void)
<BR>{
<BR> char far *save_dta;
<BR> char line[80], buffer[256];
<BR> struct fcb blk;
<BR> int i, result;
<P> /* get user input file name for dta */
<BR> printf("Enter drive and file name (no path - i.e. a:file.dat)\n");
<BR> gets(line);
<P> /* put file name in fcb */
<BR> if (!parsfnm(line, &blk, 1))
<BR> {
<BR> printf("Error in call to parsfnm\n");
<BR> exit(1);
<BR> }
<BR> printf("Drive #%d File: %s\n\n", blk.fcb_drive,
blk.fcb_name);
<P> /* open file with DOS FCB open file */
<BR> bdosptr(0x0F, &blk, 0);
<P> /* save old dta, and set new one */
<BR> save_dta = getdta();
<BR> setdta(buffer);
<P> /* set up info for the new dta */
<BR> blk.fcb_recsize = 128;
<BR> blk.fcb_random = 0L;
<BR> result = randbrd(&blk, 1);
<P> /* check results from randbrd */
<BR> if (!result)
<BR> printf("Read OK\n\n");
<BR> else
<BR> {
<BR> perror("Error during read");
<BR> exit(1);
<BR> }
<P> /* read in data from the new dta */
<BR> printf("The first 128 characters are:\n");
<BR> for (i=0; i<128; i++)
<BR> putchar(buffer[i]);
<P> /* restore previous dta */
<BR> setdta(save_dta);
<P> return 0;
<BR>}
<BR>
<P>函數名: randbwr
<BR>功 能: 隨機塊寫
<BR>用 法: int randbwr(struct fcp *fcbptr, int reccnt);
<BR>程序例:
<P>#include <process.h>
<BR>#include <string.h>
<BR>#include <stdio.h>
<BR>#include <dos.h>
<P>int main(void)
<BR>{
<BR> char far *save_dta;
<BR> char line[80];
<BR> char buffer[256] = "RANDBWR test!";
<BR> struct fcb blk;
<BR> int result;
<P> /* get new file name from user */
<BR> printf("Enter a file name to create (no path - ie. a:file.dat\n");
<BR> gets(line);
<P> /* parse the new file name to the dta */
<BR> parsfnm(line,&blk,1);
<BR> printf("Drive #%d File: %s\n", blk.fcb_drive, blk.fcb_name);
<P> /* request DOS services to create file */
<BR> if (bdosptr(0x16, &blk, 0) == -1)
<BR> {
<BR> perror("Error creating file");
<BR> exit(1);
<BR> }
<P> /* save old dta and set new dta */
<BR> save_dta = getdta();
<BR> setdta(buffer);
<P> /* write new records */
<BR> blk.fcb_recsize = 256;
<BR> blk.fcb_random = 0L;
<BR> result = randbwr(&blk, 1);
<P> if (!result)
<BR> printf("Write OK\n");
<BR> else
<BR> {
<BR> perror("Disk error");
<BR> exit(1);
<BR> }
<P> /* request DOS services to close the file */
<BR> if (bdosptr(0x10, &blk, 0) == -1)
<BR> {
<BR> perror("Error closing file");
<BR> exit(1);
<BR> }
<P> /* reset the old dta */
<BR> setdta(save_dta);
<P> return 0;
<BR>}
<BR>
<BR>
<P>函數名: random
<BR>功 能: 隨機數發生器
<BR>用 法: int random(int num);
<BR>程序例:
<P>#include <stdlib.h>
<BR>#include <stdio.h>
<BR>#include <time.h>
<P>/* prints a random number in the range 0 to 99 */
<BR>int main(void)
<BR>{
<BR> randomize();
<BR> printf("Random number in the 0-99 range: %d\n", random
(100));
<BR> return 0;
<BR>}
<BR>
<BR>
<P>函數名: randomize
<BR>功 能: 初始化隨機數發生器
<BR>用 法: void randomize(void);
<BR>程序例:
<P>#include <stdlib.h>
<BR>#include <stdio.h>
<BR>#include <time.h>
<P>int main(void)
<BR>{
<BR> int i;
<P> randomize();
<BR> printf("Ten random numbers from 0 to 99\n\n");
<BR> for(i=0; i<10; i++)
<BR> printf("%d\n", rand() % 100);
<BR> return 0;
<BR>}
<BR>
<BR>
<P>函數名: read
<BR>功 能: 從文件中讀
<BR>用 法: int read(int handle, void *buf, int nbyte);
<BR>程序例:
<P>#include <stdio.h>
<BR>#include <io.h>
<BR>#include <alloc.h>
<BR>#include <fcntl.h>
<BR>#include <process.h>
<P>int main(void)
<BR>{
<BR> void *buf;
<BR> int handle, bytes;
<P> buf = malloc(10);
<P>/*
<BR> Looks for a file in the current directory named TEST.$$$
and attempts
<BR> to read 10 bytes from it. To use this example you
should create the
<BR> file TEST.$$$
<BR>*/
<BR> if ((handle =
<BR> open("TEST.$$$", O_RDONLY | O_BINARY,
S_IWRITE | S_IREAD)) == -1)
<BR> {
<BR> printf("Error Opening File\n");
<BR> exit(1);
<BR> }
<P> if ((bytes = read(handle, buf, 10)) == -1) {
<BR> printf("Read Failed.\n");
<BR> exit(1);
<BR> }
<BR> else {
<BR> printf("Read: %d bytes read.\n", bytes);
<BR> }
<BR> return 0;
<BR>}
<BR>
<BR>
<P>函數名: realloc
<BR>功 能: 重新分配主存
<BR>用 法: void *realloc(void *ptr, unsigned newsize);
<BR>程序例:
<P>#include <stdio.h>
<BR>#include <alloc.h>
<BR>#include <string.h>
<P>int main(void)
<BR>{
<BR> char *str;
<P> /* allocate memory for string */
<BR> str = malloc(10);
<P> /* copy "Hello" into string */
<BR> strcpy(str, "Hello");
<P> printf("String is %s\n Address is %p\n", str, str);
<BR> str = realloc(str, 20);
<BR> printf("String is %s\n New address is %p\n", str,
str);
<P> /* free memory */
<BR> free(str);
<P> return 0;
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