C语言库函数（五）

liu0013

墨衍会员 · AI 创作全网分发码龄22年

关注

原创最新推荐文章于 2026-05-11 11:32:15 发布 1.7k 阅读 AI 写同款· GEO 优化 ›

C语言库函数全面解读CHM版 C语言库函数是一组预先编写好的代码集合，这些函数封装了常见的功能，比如数据处理、数学计算、字符串操作等。程序员可以直接调用这些库函数，不必从头开始编写重复的代码，大大提高了开发效率。阅读详情

函数名: setjmp
功能: 非局部转移
用法: int setjmp(jmp_buf env);
程序例:

#include <stdio.h>
#include <process.h>
#include <setjmp.h>

void subroutine(void);

jmp_buf jumper;

int main(void)
{
int value;

   value = setjmp(jumper);
   if (value != 0)
   {
      printf("Longjmp with value %d/n", value);
      exit(value);
   }
   printf("About to call subroutine ... /n");
   subroutine();
   return 0;
}

void subroutine(void)
{
   longjmp(jumper,1);
}

函数名: setlinestyle
功能: 设置当前画线宽度和类型
用法: void far setlinestyle(int linestype, unsigned upattern);
程序例:

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

/* the names of the line styles supported */
char *lname[] = {
   "SOLID_LINE",
   "DOTTED_LINE",
   "CENTER_LINE",
   "DASHED_LINE",
   "USERBIT_LINE"
   };

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

int style, midx, midy, userpat;
char stylestr[40];

/* initialize graphics and local variables */
initgraph(&gdriver, &gmode, "");

   /* read result of initialization */
   errorcode = graphresult();
   if (errorcode != grOk) /* an error occurred */
   {
      printf("Graphics error: %s/n", grapherrormsg(errorcode));
      printf("Press any key to halt:");
      getch();
      exit(1); /* terminate with an error code */
   }

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

   /* a user defined line pattern */
   /* binary: "0000000000000001" */
   userpat = 1;

   for (style=SOLID_LINE; style<=USERBIT_LINE; style++)
   {
      /* select the line style */
      setlinestyle(style, userpat, 1);

/* convert style into a string */
strcpy(stylestr, lname[style]);

/* draw a line */
line(0, 0, midx-10, midy);

/* draw a rectangle */
rectangle(0, 0, getmaxx(), getmaxy());

/* output a message */
outtextxy(midx, midy, stylestr);

      /* wait for a key */
      getch();
      cleardevice();
   }

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

函数名: setmem
功能: 存值到存储区
用法: void setmem(void *addr, int len, char value);
程序例:

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

int main(void)
{
char *dest;

   dest = calloc(21, sizeof(char));
   setmem(dest, 20, 'c');
   printf("%s/n", dest);

   return 0;
}

函数名: setmode
功能: 设置打开文件方式
用法: int setmode(int handle, unsigned mode);
程序例:

#include <stdio.h>
#include <fcntl.h>
#include <io.h>

int main(void)
{
int result;

   result = setmode(fileno(stdprn), O_TEXT);
   if (result == -1)
      perror("Mode not available/n");
   else
      printf("Mode successfully switched/n");
   return 0;
}

函数名: setpalette
功能: 改变调色板的颜色
用法: void far setpalette(int index, int actural_color);
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 color, maxcolor, ht;
   int y = 10;
   char msg[80];

/* initialize graphics and local variables */
initgraph(&gdriver, &gmode, "");

maxcolor = getmaxcolor();
ht = 2 * textheight("W");

   /* display the default colors */
   for (color=1; color<=maxcolor; color++)
   {
      setcolor(color);
      sprintf(msg, "Color: %d", color);
      outtextxy(1, y, msg);
      y += ht;
   }

/* wait for a key */
getch();

   /* black out the colors one by one */
   for (color=1; color<=maxcolor; color++)
   {
      setpalette(color, BLACK);
      getch();
   }

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

函数名: setrgbpalette
功能: 定义IBM8514图形卡的颜色
用法: void far setrgbpalette(int colornum, int red, int green, int blue);
程序例:

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

int main(void)
{
   /* select a driver and mode that supports the use */
   /* of the setrgbpalette function.                 */
   int gdriver = VGA, gmode = VGAHI, errorcode;
   struct palettetype pal;
   int i, ht, y, xmax;

/* initialize graphics and local variables */
initgraph(&gdriver, &gmode, "");

/* grab a copy of the palette */
getpalette(&pal);

   /* create gray scale */
   for (i=0; i<pal.size; i++)
      setrgbpalette(pal.colors[i], i*4, i*4, i*4);

   /* display the gray scale */
   ht = getmaxy() / 16;
   xmax = getmaxx();
   y = 0;
   for (i=0; i<pal.size; i++)
   {
      setfillstyle(SOLID_FILL, i);
      bar(0, y, xmax, y+ht);
      y += ht;
   }

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

函数名: settextjustify
功能: 为图形函数设置文本的对齐方式
用法: void far settextjustify(int horiz, int vert);
程序例:

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

/* function prototype */
void xat(int x, int y);

/* horizontal text justification settings */
char *hjust[] = { "LEFT_TEXT",
                  "CENTER_TEXT",
                  "RIGHT_TEXT"
                };

/* vertical text justification settings */
char *vjust[] = { "LEFT_TEXT",
    "CENTER_TEXT",
    "RIGHT_TEXT"
                };

int main(void)
{
   /* request auto detection */
   int gdriver = DETECT, gmode, errorcode;
   int midx, midy, hj, vj;
   char msg[80];

/* initialize graphics and local variables */
initgraph(&gdriver, &gmode, "");

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

   /* loop through text justifications */
   for (hj=LEFT_TEXT; hj<=RIGHT_TEXT; hj++)
      for (vj=LEFT_TEXT; vj<=RIGHT_TEXT; vj++)
      {
         cleardevice();
         /* set the text justification */
         settextjustify(hj, vj);

/* create a message string */
sprintf(msg, "%s %s", hjust[hj], vjust[vj]);

/* create cross hairs on the screen */
xat(midx, midy);

         /* output the message */
         outtextxy(midx, midy, msg);
         getch();
      }

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

/* draw an "x" at (x, y) */
void xat(int x, int y)
{
line(x-4, y, x+4, y);
line(x, y-4, x, y+4);
}

函数名: settextstyle
功能: 为图形输出设置当前的文本属性
用法: void far settextstyle (int font, int direction, char size);
程序例:

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

/* the names of the text styles supported */
char *fname[] = { "DEFAULT font",
                  "TRIPLEX font",
                  "SMALL font",
                  "SANS SERIF font",
                  "GOTHIC font"
                };

int main(void)
{
   /* request auto detection */
   int gdriver = DETECT, gmode, errorcode;
   int style, midx, midy;
   int size = 1;

/* initialize graphics and local variables */
initgraph(&gdriver, &gmode, "");

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

settextjustify(CENTER_TEXT, CENTER_TEXT);

   /* loop through the available text styles */
   for (style=DEFAULT_FONT; style<=GOTHIC_FONT; style++)
   {
      cleardevice();
      if (style == TRIPLEX_FONT)
         size = 4;

/* select the text style */
settextstyle(style, HORIZ_DIR, size);

      /* output a message */
      outtextxy(midx, midy, fname[style]);
      getch();
   }

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

函数名: settextstyle
功能: 为图形输出设置当前的文本属性
用法: void far settextstyle (int font, int direction, char size);
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 style, midx, midy;
   int size = 1;

/* initialize graphics and local variables */
initgraph(&gdriver, &gmode, "");

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

settextjustify(CENTER_TEXT, CENTER_TEXT);

   /* loop through the available text styles */
   for (style=DEFAULT_FONT; style<=GOTHIC_FONT; style++)
   {
      cleardevice();
      if (style == TRIPLEX_FONT)
         size = 4;

/* select the text style */
settextstyle(style, HORIZ_DIR, size);

      /* output a message */
      outtextxy(midx, midy, fname[style]);
      getch();
   }

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

函数名: settime
功能: 设置系统时间
用法: void settime(struct time *timep);
程序例:

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

int main(void)
{
struct time t;

   gettime(&t);
   printf("The current minute is: %d/n", t.ti_min);
   printf("The current hour is: %d/n", t.ti_hour);
   printf("The current hundredth of a second is: %d/n", t.ti_hund);
   printf("The current second is: %d/n", t.ti_sec);

   /* Add one to the minutes struct element and then call settime */
   t.ti_min++;
   settime(&t);

   return 0;
}

函数名: setusercharsize
功能: 为矢量字体改变字符宽度和高度
用法: void far setusercharsize(int multx, int dirx, int multy, int diry);
程序例:

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

int main(void)
{
/* request autodetection */
int gdriver = DETECT, gmode, errorcode;

/* initialize graphics and local variables */
initgraph(&gdriver, &gmode, "");

   /* read result of initialization */
   errorcode = graphresult();
   if (errorcode != grOk)      /* an error occurred */
   {
      printf("Graphics error: %s/n", grapherrormsg(errorcode));
      printf("Press any key to halt:");
      getch();
      exit(1);                 /* terminate with an error code */
   }

/* select a text style */
settextstyle(TRIPLEX_FONT, HORIZ_DIR, 4);

/* move to the text starting position */
moveto(0, getmaxy() / 2);

/* output some normal text */
outtext("Norm ");

   /* make the text 1/3 the normal width */
   setusercharsize(1, 3, 1, 1);
   outtext("Short ");

   /* make the text 3 times normal width */
   setusercharsize(3, 1, 1, 1);
   outtext("Wide");

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

函数名: setvbuf
功能: 把缓冲区与流相关
用法: int setvbuf(FILE *stream, char *buf, int type, unsigned size);
程序例:

#include <stdio.h>

int main(void)
{
FILE *input, *output;
char bufr[512];

input = fopen("file.in", "r+b");
output = fopen("file.out", "w");

   /* set up input stream for minimal disk access,
      using our own character buffer */
   if (setvbuf(input, bufr, _IOFBF, 512) != 0)
      printf("failed to set up buffer for input file/n");
   else
      printf("buffer set up for input file/n");

   /* set up output stream for line buffering using space that
      will be obtained through an indirect call to malloc */
   if (setvbuf(output, NULL, _IOLBF, 132) != 0)
      printf("failed to set up buffer for output file/n");
   else
      printf("buffer set up for output file/n");

/* perform file I/O here */

   /* close files */
   fclose(input);
   fclose(output);
   return 0;
}

函数名: setvect
功能: 设置中断矢量入口
用法: void setvect(int intr_num, void interrupt(*isr)());
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>

#define INTR 0X1C /* The clock tick interrupt */

void interrupt ( *oldhandler)(void);

int count=0;

void interrupt handler(void)
{
/* increase the global counter */
count++;

/* 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;
}

函数名: setverify
功能: 设置验证状态
用法: void setverify(int value);
程序例:

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

int main(void)
{
int verify_flag;

printf("Enter 0 to set verify flag off/n");
printf("Enter 1 to set verify flag on/n");

verify_flag = getch() - 0;

setverify(verify_flag);

   if (getverify())
      printf("DOS verify flag is on/n");
   else
      printf("DOS verify flag is off/n");

   return 0;
}

函数名: setviewport
功能: 为图形输出设置当前视口
用法: void far setviewport(int left, int top, int right,
int bottom, int clipflag);
程序例:

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

#define CLIP_ON 1 /* activates clipping in viewport */

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

/* initialize graphics and local variables */
initgraph(&gdriver, &gmode, "");

setcolor(getmaxcolor());

/* message in default full-screen viewport */
outtextxy(0, 0, "* <-- (0, 0) in default viewport");

/* create a smaller viewport */
setviewport(50, 50, getmaxx()-50, getmaxy()-50, CLIP_ON);

/* display some text */
outtextxy(0, 0, "* <-- (0, 0) in smaller viewport");

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

函数名: setvisualpage
功能: 设置可见图形页号
用法: void far setvisualpage(int pagenum);
程序例:

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

int main(void)
{
   /* select a driver and mode that supports */
   /* multiple pages.                        */
   int gdriver = EGA, gmode = EGAHI, errorcode;
   int x, y, ht;

/* initialize graphics and local variables */
initgraph(&gdriver, &gmode, "");

   x = getmaxx() / 2;
   y = getmaxy() / 2;
   ht = textheight("W");

/* select the off screen page for drawing */
setactivepage(1);

/* draw a line on page #1 */
line(0, 0, getmaxx(), getmaxy());

   /* output a message on page #1 */
   settextjustify(CENTER_TEXT, CENTER_TEXT);
   outtextxy(x, y, "This is page #1:");
   outtextxy(x, y+ht, "Press any key to halt:");

/* select drawing to page #0 */
setactivepage(0);

   /* output a message on page #0 */
   outtextxy(x, y, "This is page #0.");
   outtextxy(x, y+ht, "Press any key to view page #1:");
   getch();

/* select page #1 as the visible page */
setvisualpage(1);

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

函数名: setwritemode
功能: 设置图形方式下画线的输出模式
用法: void far setwritemode(int mode);
程序例:

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

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

/* initialize graphics and local variables */
initgraph(&gdriver, &gmode, "");

xmax = getmaxx();
ymax = getmaxy();

/* select XOR drawing mode */
setwritemode(XOR_PUT);

   /* draw a line */
   line(0, 0, xmax, ymax);
   getch();

   /* erase the line by drawing over it */
   line(0, 0, xmax, ymax);
   getch();

/* select overwrite drawing mode */
setwritemode(COPY_PUT);

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

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

函数名: signal
功能: 设置某一信号的对应动作
用法: int signal(int sig, sigfun fname);
程序例:

/* This example installs a signal handler routine for SIGFPE,
   catches an integer overflow condition, makes an adjustment
   to AX register, and returns. This example program MAY cause
   your computer to crash, and will produce runtime errors
   depending on which memory model is used.
*/

#pragma inline
#include <stdio.h>
#include <signal.h>

void Catcher(int sig, int type, int *reglist)
{
printf("Caught it!/n");
*(reglist + 8) = 3; /* make return AX = 3 */
}

int main(void)
{
   signal(SIGFPE, Catcher);
   asm     mov     ax,07FFFH       /* AX = 32767 */
   asm     inc     ax              /* cause overflow */
   asm     into                    /* activate handler */

   /* The handler set AX to 3 on return. If that hadn't happened,
      there would have been another exception when the next 'into'
      was executed after the 'dec' instruction. */
   asm     dec     ax              /* no overflow now */
   asm     into                    /* doesn't activate */
   return 0;
}

函数名: sin
功能: 正弦函数
用法: double sin(double x);
程序例:

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

int main(void)
{
double result, x = 0.5;

   result = sin(x);
   printf("The sin() of %lf is %lf/n", x, result);
   return 0;
}

函数名: sinh
功能: 双曲正弦函数
用法: double sinh(double x);
程序例:

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

int main(void)
{
double result, x = 0.5;

   result = sinh(x);
   printf("The hyperbolic sin() of %lf is %lf/n", x, result);
   return 0;
}

函数名: sleep
功能: 执行挂起一段时间
用法: unsigned sleep(unsigned seconds);
程序例:

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

int main(void)
{
int i;

   for (i=1; i<5; i++)
   {
      printf("Sleeping for %d seconds/n", i);
      sleep(i);
   }
   return 0;
}

函数名: sopen
功能: 打开一共享文件
用法: int sopen(char *pathname, int access, int shflag, int permiss);
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;
int status;

handle = sopen("c://autoexec.bat", O_RDONLY, SH_DENYNO, S_IREAD);

   if (!handle)
   {
      printf("sopen failed/n");
      exit(1);
   }

   status = access("c://autoexec.bat", 6);
   if (status == 0)
      printf("read/write access allowed/n");
   else
      printf("read/write access not allowed/n");

close(handle);
return 0;
}

收录于