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C语言教程C语言函数: S

C语言函数: S

更新时间:2013-03-25 13:02:43 |

函数名: sbrk
功  能: 改变数据段空间位置
用  法: char *sbrk(int incr);
程序例:

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

int main(void)
{
   printf("Changing allocation with sbrk()\n");
   printf("Before sbrk() call: %lu bytes free\n",
   (unsigned long) coreleft());
   sbrk(1000);
   printf(" After sbrk() call: %lu bytes free\n",
   (unsigned long) coreleft());
   return 0;
}
 
 

函数名: scanf
功  能: 执行格式化输入
用  法: int scanf(char *format[,argument,...]);
程序例:

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

int main(void)
{
   char label[20];
   char name[20];
   int entries = 0;
   int loop, age;
   double salary;

   struct Entry_struct
   {
      char  name[20];
      int   age;
      float salary;
   } entry[20];

/* Input a label as a string of characters restricting to 20 characters */
   printf("\n\nPlease enter a label for the chart: ");
   scanf("%20s", label);
   fflush(stdin);  /* flush the input stream in case of bad input */

/* Input number of entries as an integer */
   printf("How many entries will there be? (less than 20) ");
   scanf("%d", &entries);
   fflush(stdin);   /* flush the input stream in case of bad input */

/* input a name restricting input to only letters upper or lower case */
   for (loop=0;loop<entries;++loop)
   {
      printf("Entry %d\n", loop);
      printf("  Name   : ");
      scanf("%[A-Za-z]", entry[loop].name);
      fflush(stdin);  /* flush the input stream in case of bad input */

/* input an age as an integer */
      printf("  Age    : ");
      scanf("%d", &entry[loop].age);
      fflush(stdin);  /* flush the input stream in case of bad input */

/* input a salary as a float */
      printf("  Salary : ");
      scanf("%f", &entry[loop].salary);
      fflush(stdin); /* flush the input stream in case of bad input */
   }

/* Input a name, age and salary as a string, integer, and double */
   printf("\nPlease enter your name, age and salary\n");
   scanf("%20s %d %lf", name, &age, &salary);
 

/* Print out the data that was input */
   printf("\n\nTable %s\n",label);
   printf("Compiled by %s  age %d  $%15.2lf\n", name, age, salary);
   printf("-----------------------------------------------------\n");
   for (loop=0;loop<entries;++loop)
      printf("%4d | %-20s | %5d | %15.2lf\n",
         loop + 1,
  entry[loop].name,
  entry[loop].age,
         entry[loop].salary);
   printf("-----------------------------------------------------\n");
   return 0;
}
 
 

函数名: searchpath
功  能: 搜索DOS路径
用  法: char *searchpath(char *filename);
程序例:

#include <stdio.h>
#include <dir.h>

int main(void)
{
   char *p;

   /* Looks for TLINK and returns a pointer
      to the path  */
   p = searchpath("TLINK.EXE");
   printf("Search for TLINK.EXE : %s\n", p);

   /* Looks for non-existent file  */
   p = searchpath("NOTEXIST.FIL");
   printf("Search for NOTEXIST.FIL : %s\n", p);

   return 0;
}
 
 

函数名: sector
功  能: 画并填充椭圆扇区
用  法: void far sector(int x, int y, int stangle, int endangle);
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 midx, midy, i;
   int stangle = 45, endangle = 135;
   int xrad = 100, yrad = 50;

   /* 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;

   /* loop through the fill patterns */
   for (i=EMPTY_FILL; i<USER_FILL; i++)
   {
      /* set the fill style */
      setfillstyle(i, getmaxcolor());

      /* draw the sector slice */
      sector(midx, midy, stangle, endangle, xrad, yrad);

      getch();
   }

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

函数名: segread
功  能: 读段寄存器值
用  法: void segread(struct SREGS *segtbl);
程序例:

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

int main(void)
{
   struct SREGS segs;

   segread(&segs);
   printf("Current segment register settings\n\n");
   printf("CS: %X   DS: %X\n", segs.cs, segs.ds);
   printf("ES: %X   SS: %X\n", segs.es, segs.ss);

   return 0;
}
 
 

函数名: setactivepage
功  能: 设置图形输出活动页
用  法: void far setactivepage(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, "");

   /* 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 */
   }

   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: setallpallette
功  能: 按指定方式改变所有的调色板颜色
用  法: void far setallpallette(struct palette, far *pallette);
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;
   struct palettetype pal;
   int color, maxcolor, ht;
   int y = 10;
   char msg[80];

   /* 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 */
   }

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

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

   /* display the default palette 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();
   }

   /* restore the palette colors */
   setallpalette(&pal);

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

函数名: setaspectratio
功  能: 设置图形纵横比
用  法: void far setaspectratio(int xasp, int yasp);
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 xasp, yasp, midx, midy;

   /* 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;
   setcolor(getmaxcolor());

   /* get current aspect ratio settings */
   getaspectratio(&xasp, &yasp);

   /* draw normal circle */
   circle(midx, midy, 100);
   getch();

   /* claer the screen */
   cleardevice();

   /* adjust the aspect for a wide circle */
   setaspectratio(xasp/2, yasp);
   circle(midx, midy, 100);
   getch();

   /* adjust the aspect for a narrow circle */
   cleardevice();
   setaspectratio(xasp, yasp/2);
   circle(midx, midy, 100);

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

函数名: setbkcolor
功  能: 用调色板设置当前背景颜色
用  法: void far setbkcolor(int color);
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 background colors.            */
   int gdriver = EGA, gmode = EGAHI, errorcode;
   int bkcol, maxcolor, x, y;
   char msg[80];

   /* 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 */
   }

   /* maximum color index supported */
   maxcolor = getmaxcolor();

   /* for centering text messages */
   settextjustify(CENTER_TEXT, CENTER_TEXT);
   x = getmaxx() / 2;
   y = getmaxy() / 2;

   /* loop through the available colors */
   for (bkcol=0; bkcol<=maxcolor; bkcol++)
   {
      /* clear the screen */
      cleardevice();

      /* select a new background color */
      setbkcolor(bkcol);

      /* output a messsage */
      if (bkcol == WHITE)
  setcolor(EGA_BLUE);
      sprintf(msg, "Background color: %d", bkcol);
      outtextxy(x, y, msg);
      getch();
   }

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

函数名: setblock
功  能: 修改先前已分配的DOS存储段大小
用  法: int setblock(int seg, int newsize);
程序例:

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

int main(void)
{
   unsigned int size, segp;
   int stat;

   size = 64; /* (64 x 16) = 1024 bytes */
   stat = allocmem(size, &segp);
   if (stat == -1)
      printf("Allocated memory at segment: %X\n", segp);
   else
   {
      printf("Failed: maximum number of paragraphs available is %d\n",
      stat);
      exit(1);
   }

   stat = setblock(segp, size * 2);
   if (stat == -1)
      printf("Expanded memory block at segment: %X\n", segp);
   else
      printf("Failed: maximum number of paragraphs available is %d\n",
             stat);

   freemem(segp);

   return 0;
}
 
 

函数名: setbuf
功  能: 把缓冲区与流相联
用  法: void setbuf(FILE *steam, char *buf);
程序例:

#include <stdio.h>

/* BUFSIZ is defined in stdio.h */
char outbuf[BUFSIZ];

int main(void)
{
   /* attach a buffer to the standard output stream */
   setbuf(stdout, outbuf);

   /* put some characters into the buffer */
   puts("This is a test of buffered output.\n\n");
   puts("This output will go into outbuf\n");
   puts("and won't appear until the buffer\n");
   puts("fills up or we flush the stream.\n");

   /* flush the output buffer */
   fflush(stdout);

   return 0;
}
 
 

函数名: setcbrk
功  能: 设置Control-break
用  法: int setcbrk(int value);
程序例:

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

int main(void)
{
   int break_flag;

   printf("Enter 0 to turn control break off\n");
   printf("Enter 1 to turn control break on\n");

   break_flag = getch() - 0;

   setcbrk(break_flag);

   if (getcbrk())
      printf("Cntrl-brk flag is on\n");
   else
      printf("Cntrl-brk flag is off\n");
   return 0;
}
 
 
 

函数名: setcolor
功  能: 设置当前画线颜色
用  法: void far setcolor(int color);
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 drawing colors.               */
   int gdriver = EGA, gmode = EGAHI, errorcode;
   int color, maxcolor, x, y;
   char msg[80];

   /* 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 */
   }

   /* maximum color index supported */
   maxcolor = getmaxcolor();

   /* for centering text messages */
   settextjustify(CENTER_TEXT, CENTER_TEXT);
   x = getmaxx() / 2;
   y = getmaxy() / 2;

   /* loop through the available colors */
   for (color=1; color<=maxcolor; color++)
   {
      /* clear the screen */
      cleardevice();

      /* select a new background color */
      setcolor(color);

      /* output a messsage */
      sprintf(msg, "Color: %d", color);
      outtextxy(x, y, msg);
      getch();
   }

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

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