wdg_022s.txt

c编程宝典,详细介绍有关c的资料

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();