C语言的函数!

内财数模协会 · 发表于 2004-5-8 17:29:37

<

>函数名: enable
功能: 开放硬件中断
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;
}

内财数模协会 · 发表于 2004-5-8 17:29:47

<

>函数名: eof
功能: 检测文件结束
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;
}

内财数模协会 · 发表于 2004-5-8 17:29:56

<

>函数名: exec...
功 能: 装入并运行其它程序的函数
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); printf("About to exec child with arg1 arg2 ...\n");
execv("CHILD.EXE", argv); perror("exec error"); exit(1);
}

内财数模协会 · 发表于 2004-5-8 17:30:06

<

>函数名: exit
功能: 终止程序
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;
}

内财数模协会 · 发表于 2004-5-8 17:30:15

<

>函数名: exp
功能: 指数函数
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;
}

内财数模协会 · 发表于 2004-5-8 17:33:10

<

>函数名: fabs
功能: 返回浮点数的绝对值
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;
}

内财数模协会 · 发表于 2004-5-8 17:33:24

<

>函数名: farcalloc
功能: 从远堆栈中申请空间
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;
}

内财数模协会 · 发表于 2004-5-8 17:33:32

<

>函数名: farcoreleft
功能: 返回远堆中未作用存储区大小
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;
}

内财数模协会 · 发表于 2004-5-8 17:33:44

<

>函数名: farfree
功能: 从远堆中释放一块
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;
}

内财数模协会 · 发表于 2004-5-8 17:33:54

<

>函数名: farmalloc
功能: 从远堆中分配存储块
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;
}

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