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函数大全(l开头)

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韩冰

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发表于 2004-10-4 02:58 |只看该作者 |倒序浏览

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<

>函数名: labs 
用法: long labs(long n);
程序例: 
<

>#include <STDIO.H>
#include <MATH.H>
<

>int main(void)
{
long result;
long x = -12345678L; 
<

>result= labs(x);
printf("number: %ld abs value: %ld\n",
x, result); 
<

>return 0;
}



<

>函数名: ldexp 
功能: 计算value*2的幂
用法: double ldexp(double value, int exp);
程序例: 
<

>#include <STDIO.H>
#include <MATH.H>
<

>int main(void)
{
double value;
double x = 2; 
<

>/* ldexp raises 2 by a power of 3
then multiplies the result by 2 */
value = ldexp(x,3);
printf("The ldexp value is: %lf\n",
value); 
<

>return 0;
}


<

>函数名: ldiv 
功能: 两个长整型数相除, 返回商和余数
用法: ldiv_t ldiv(long lnumer, long ldenom);
程序例: 
<

>/* ldiv example */ 
<

>#include <STDLIB.H>
#include <STDIO.H>
<

>int main(void)
{
ldiv_t lx; 
<

>lx = ldiv(100000L, 30000L);
printf("100000 div 30000 = %ld remainder %ld\n", lx.quot, lx.rem);
return 0; 
} 

<

>函数名: lfind 
功能: 执行线性搜索
用法: void *lfind(void *key, void *base, int *nelem, int width,
int (*fcmp)());
程序例: 
<

>#include <STDIO.H>
#include <STDLIB.H>
<

>int compare(int *x, int *y)
{
return( *x - *y );
} 
<

>int main(void)
{
int array[5] = {35, 87, 46, 99, 12};
size_t nelem = 5;
int key;
int *result; 
<

>key = 99;
result = lfind(&key, array, &nelem,
sizeof(int), (int(*)(const void *,const void *))compare);
if (result)
printf("Number %d found\n",key);
else
printf("Number %d not found\n",key); 
<

>return 0;
} 


<

>函数名: line 
功能: 在指定两点间画一直线
用法: void far line(int x0, int y0, int x1, int y1);
程序例: 
<

>#include <GRAPHICS.H>
#include <STDLIB.H>
#include <STDIO.H>
#include <CONIO.H>
<

>int main(void)
{
/* request auto detection */
int gdriver = DETECT, gmode, errorcode;
int xmax, ymax; 
<

>/* 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("

ress any key to halt:");
getch();
exit(1);
} 
<

>setcolor(getmaxcolor());
xmax = getmaxx();
ymax = getmaxy(); 
<

>/* draw a diagonal line */
line(0, 0, xmax, ymax); 
<

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


函数名: linerel 
功能: 从当前位置点(CP)到与CP有一给定相对距离的点画一直线
用法: void far linerel(int dx, int dy);
程序例: 
#include <GRAPHICS.H>
#include <STDLIB.H>
#include <STDIO.H>
#include <CONIO.H>
int main(void)
{
/* request auto detection */
int gdriver = DETECT, gmode, errorcode;
char msg[80]; 
/* initialize graphics and local variables */
initgraph(&gdriver, &gmode, ""); 
/* read result of initialization */
errorcode = graphresult();
if (errorcode != grOk)
{
printf("Graphics error: %s\n",
grapherrormsg(errorcode));
printf("Press any key to halt:");
getch();
exit(1);
} 
/* move the C.P. to location (20, 30) */
moveto(20, 30); 
/* create and output a
message at (20, 30) */
sprintf(msg, " (%d, %d)", getx(), gety());
outtextxy(20, 30, msg); 
/* draw a line to a point a relative
distance away from the current
value of C.P. */
linerel(100, 100); 
/* create and output a message at C.P. */
sprintf(msg, " (%d, %d)", getx(), gety());
outtext(msg); 
/* clean up */
getch();
closegraph();
return 0;
} 

函数名: localtime
功能: 把日期和时间转变为结构
用法: struct tm *localtime(long *clock);
程序例: 
#include <TIME.H>
#include <STDIO.H>
#include <DOS.H>
int main(void)
{
time_t timer;
struct tm *tblock; 
/* gets time of day */
timer = time(NULL); 
/* converts date/time to a structure */
tblock = localtime(&timer); 
printf("Local time is: %s", asctime(tblock)); 
return 0;
}


函数名: lock 
功能: 设置文件共享锁
用法: int lock(int handle, long offset, long length);
程序例: 
#include <IO.H>
#include <FCNTL.H>
#include <SYS\STAT.H>
#include <PROCESS.H>
#include <SHARE.H>
#include <STDIO.H>
int main(void)
{
int handle, status;
long length; 
/* Must have DOS Share.exe loaded for */
/* file locking to function properly */ 
handle = sopen("c:\\autoexec.bat",
O_RDONLY,SH_DENYNO,S_IREAD); 
if (handle < 0)
{
printf("sopen failed\n");
exit(1);
} 
length = filelength(handle);
status = lock(handle,0L,length/2); 
if (status == 0)
printf("lock succeeded\n");
else
printf("lock failed\n"); 
status = unlock(handle,0L,length/2); 
if (status == 0)
printf("unlock succeeded\n");
else
printf("unlock failed\n"); 
close(handle);
return 0;
}


函数名: log 
功能: 对数函数ln(x)
用法: double log(double x);
程序例: 
#include <MATH.H>
#include <STDIO.H>
int main(void)
{
double result;
double x = 8.6872; 
result = log(x);
printf("The natural log of %lf is %lf\n", x, result); 
return 0;
}


函数名: log10 
功能: 对数函数log
用法: double log10(double x);
程序例: 
#include <MATH.H>
#include <STDIO.H>
int main(void)
{
double result;
double x = 800.6872; 
result = log10(x);
printf("The common log of %lf is %lf\n", x, result); 
return 0;
}



函数名: longjump 
功能: 执行非局部转移
用法: void longjump(jmp_buf env, int val);
程序例: 
#include <STDIO.H>
#include <SETJMP.H>
#include <STDLIB.H>
void subroutine(jmp_buf); 
int main(void)
{ 
int value;
jmp_buf jumper; 
value = setjmp(jumper);
if (value != 0)
{
printf("Longjmp with value %d\n", value);
exit(value);
}
printf("About to call subroutine ... \n");
subroutine(jumper); 
return 0;
} 
void subroutine(jmp_buf jumper)
{
longjmp(jumper,1);
}



函数名: lowvideo
功能: 选择低亮度字符
用法: void lowvideo(void);
程序例: 
#include <CONIO.H>
int main(void)
{
clrscr(); 
highvideo();
cprintf("High Intesity Text\r\n");
lowvideo();
gotoxy(1,2);
cprintf("Low Intensity Text\r\n"); 
return 0;
}



函数名: lrotl, _lrotl 
功能: 将无符号长整型数向左循环移位
用法: unsigned long lrotl(unsigned long lvalue, int count);
unsigned long _lrotl(unsigned long lvalue, int count);
程序例: 
/* lrotl example */
#include <STDLIB.H>
#include <STDIO.H>
int main(void)
{
unsigned long result;
unsigned long value = 100; 
result = _lrotl(value,1);
printf("The value %lu rotated left one bit is: %lu\n", value, result); 
return 0;
}


函数名: lsearch 
功能: 线性搜索
用法: void *lsearch(const void *key, void *base, size_t *nelem,
size_t width, int (*fcmp)(const void *, const void *));
程序例: 
#include <STDIO.H>
#include <STDLIB.H>
int compare(int *x, int *y)
{
return( *x - *y );
} 
int main(void)
{
int array[5] = {35, 87, 46, 99, 12};
size_t nelem = 5;
int key;
int *result; 
key = 99;
result = lfind(&key, array, &nelem,
sizeof(int), (int(*)(const void *,const void *))compare);
if (result)
printf("Number %d found\n",key);
else
printf("Number %d not found\n",key); 
return 0;
}



函数名: lseek 
功能: 移动文件读/写指针
用法: long lseek(int handle, long offset, int fromwhere);
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("TEST.$$$", O_CREAT | O_RDWR, S_IREAD | S_IWRITE); 
/* write some data to the file */
write(handle, msg, strlen(msg)); 
/* seek to the begining of the file */
lseek(handle, 0L, SEEK_SET); 
/* reads chars from the file until we hit EOF */
do
{
read(handle, &ch, 1);
printf("%c", ch);
} while (!eof(handle)); 
close(handle);
return 0;
}

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