wdg_022g.txt

c编程宝典,详细介绍有关c的资料

函数名: gcvt 
功  能: 把浮点数转换成字符串 
用  法: char *gcvt(double value, int ndigit, char *buf); 
程序例: 

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

int main(void) 
{ 
   char str[25]; 
   double num; 
   int sig = 5; /* significant digits */ 

   /* a regular number */ 
   num = 9.876; 
   gcvt(num, sig, str); 
   printf("string = %s\n", str); 

   /* a negative number */ 
   num = -123.4567; 
   gcvt(num, sig, str); 
   printf("string = %s\n", str); 

   /* scientific notation */ 
   num = 0.678e5; 
   gcvt(num, sig, str); 
   printf("string = %s\n", str); 

   return(0); 
} 
  
  
  

函数名: geninterrupt 
功  能: 产生一个软中断 
用  法: void geninterrupt(int intr_num); 
程序例: 

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

/* function prototype */ 
void writechar(char ch); 

int main(void) 
{ 
   clrscr(); 
   gotoxy(80,25); 
   writechar('*'); 
   getch(); 
   return 0; 
} 

/* 
   outputs a character at the current cursor 
   position using the video BIOS to avoid the 
   scrolling of the screen when writing to 
   location (80,25). 
*/ 

void writechar(char ch) 
{ 
   struct text_info ti; 
   /* grab current text settings */ 
   gettextinfo(&ti); 
   /* interrupt 0x10 sub-function 9 */ 
   _AH = 9; 
   /* character to be output */ 
   _AL = ch; 
   _BH = 0;                  /* video page */ 
   _BL = ti.attribute;  /* video attribute */ 
   _CX = 1;           /* repetition factor */ 
   geninterrupt(0x10);  /* output the char */ 
} 
  
  

函数名: getarccoords 
功  能: 取得最后一次调用arc的坐标 
用  法: void far getarccoords(struct arccoordstype far *arccoords); 
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 arccoordstype arcinfo; 
   int midx, midy; 
   int stangle = 45, endangle = 270; 
   char sstr[80], estr[80]; 

/* 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("Press any key to halt:"); 
      getch(); 
/* terminate with an error code */ 
      exit(1); 
   } 

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

/* draw arc and get coordinates */ 
   setcolor(getmaxcolor()); 
   arc(midx, midy, stangle, endangle, 100); 
   getarccoords(&arcinfo); 

/* convert arc information into strings */ 
   sprintf(sstr, "*- (%d, %d)", 
           arcinfo.xstart, arcinfo.ystart); 
   sprintf(estr, "*- (%d, %d)", 
           arcinfo.xend, arcinfo.yend); 

   /* output the arc information */ 
   outtextxy(arcinfo.xstart, 
             arcinfo.ystart, sstr); 
   outtextxy(arcinfo.xend, 
             arcinfo.yend, estr); 

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

函数名: getaspectratio 
功  能: 返回当前图形模式的纵横比 
用  法: void far getaspectratio(int far *xasp, int far *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(); 
/* an error occurred */ 
   if (errorcode != grOk) 
   { 
      printf("Graphics error: %s\n", 
             grapherrormsg(errorcode)); 
      printf("Press any key to halt:"); 
      getch(); 
/* terminate with an error code */ 
      exit(1); 
   } 

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

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

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

/* draw wide circle */ 
   cleardevice(); 
   setaspectratio(xasp/2, yasp); 
   circle(midx, midy, 100); 
   getch(); 

/* draw narrow circle */ 
   cleardevice(); 
   setaspectratio(xasp, yasp/2); 
   circle(midx, midy, 100); 

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

函数名: getbkcolor 
功  能: 返回当前背景颜色 
用  法: int far getbkcolor(void); 
程序例: 

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

int main(void) 
{ 
   /* request auto detection */ 
   int gdriver = DETECT, gmode, errorcode; 
   int bkcolor, midx, midy; 
   char bkname[35]; 

/* 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("Press any key to halt:"); 
      getch(); 
/* terminate with an error code */ 
      exit(1); 
   } 

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

/* for centering text on the display */ 
   settextjustify(CENTER_TEXT, CENTER_TEXT); 

/* get the current background color */ 
   bkcolor = getbkcolor(); 

/* convert color value into a string */ 
   itoa(bkcolor, bkname, 10); 
   strcat(bkname, 
 " is the current background color."); 

/* display a message */ 
   outtextxy(midx, midy, bkname); 

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

函数名: getc 
功  能: 从流中取字符 
用  法: int getc(FILE *stream); 
程序例: 

#include <stdio.h> 

int main(void) 
{ 
   char ch; 

   printf("Input a character:"); 
/* read a character from the 
   standard input stream */ 
   ch = getc(stdin); 
   printf("The character input was: '%c'\n", 
          ch); 
   return 0; 
} 
  
  
  

函数名: getcbrk 
功  能: 获取Control_break设置 
用  法: int getcbrk(void); 
程序例: 

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

int main(void) 
{ 
   if (getcbrk()) 
      printf("Cntrl-brk flag is on\n"); 
   else 
      printf("Cntrl-brk flag is off\n"); 

   return 0; 
} 
  
  

函数名: getch 
功  能: 从控制台无回显地取一个字符 
用  法: int getch(void); 
程序例: 

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

int main(void) 
{ 
   char ch; 

   printf("Input a character:"); 
   ch = getche(); 
   printf("\nYou input a '%c'\n", ch); 
   return 0; 
} 
  
  

函数名: getchar 
功  能: 从stdin流中读字符 
用  法: int getchar(void); 
程序例: 

#include <stdio.h> 

int main(void) 
{ 
   int c; 

   /* Note that getchar reads from stdin and 
      is line buffered; this means it will 
      not return until you press ENTER. */ 

   while ((c = getchar()) != '\n') 
      printf("%c", c); 

   return 0; 
} 
  
  

函数名: getche 
功  能: 从控制台取字符(带回显) 
用  法: int getche(void); 
程序例: 

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

int main(void) 
{ 
   char ch; 

   printf("Input a character:"); 
   ch = getche(); 
   printf("\nYou input a '%c'\n", ch); 
   return 0; 
} 
  
  

函数名: getcolor 
功  能: 返回当前画线颜色 
用  法: int far getcolor(void); 
程序例: 

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

int main(void) 
{ 
/* request auto detection */ 
   int gdriver = DETECT, gmode, errorcode; 
   int color, midx, midy; 
   char colname[35]; 

/* 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("Press any key to halt:"); 
      getch(); 
/* terminate with an error code */ 
      exit(1); 
   } 

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

/* for centering text on the display */ 
   settextjustify(CENTER_TEXT, CENTER_TEXT); 

/* get the current drawing color */ 
   color = getcolor(); 

/* convert color value into a string */ 
   itoa(color, colname, 10); 
   strcat(colname, 
   " is the current drawing color."); 

/* display a message */ 
   outtextxy(midx, midy, colname); 

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

函数名: getcurdir 
功  能: 取指定驱动器的当前目录 
用  法: int getcurdir(int drive, char *direc); 
程序例: 

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

char *current_directory(char *path) 
{ 
   strcpy(path, "X:\\");      /* fill string with form of response: X:\ */ 
   path[0] = 'A' + getdisk();    /* replace X with current drive letter */ 
   getcurdir(0, path+3);  /* fill rest of string with current directory */ 
   return(path); 
} 

int main(void) 
{ 
   char curdir[MAXPATH]; 

   current_directory(curdir); 
   printf("The current directory is %s\n", curdir); 

   return 0; 
} 
  
  

函数名: getcwd 
功  能: 取当前工作目录 
用  法: char *getcwd(char *buf, int n); 
程序例: 

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

int main(void) 
{ 
   char buffer[MAXPATH]; 

   getcwd(buffer, MAXPATH); 
   printf("The current directory is: %s\n", buffer); 
   return 0; 
} 
  
  

函数名: getdate 
功  能: 取DOS日期 
用  法: void getdate(struct *dateblk); 
程序例: 

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

int main(void) 
{ 
   struct date d; 

   getdate(&d); 
   printf("The current year is: %d\n", 
   d.da_year); 
   printf("The current day is: %d\n", 
   d.da_day); 
   printf("The current month is: %d\n", 
   d.da_mon); 
   return 0; 
} 
  
  

函数名: getdefaultpalette 
功  能: 返回调色板定义结构 
用  法: struct palettetype *far getdefaultpalette(void); 
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 i; 

/* structure for returning palette copy */ 
   struct palettetype far *pal=(void *) 0; 

/* 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("Press any key to halt:"); 
      getch(); 
/* terminate with an error code */ 
      exit(1); 
   } 

   setcolor(getmaxcolor()); 

/* return a pointer to the default palette */ 
   pal = getdefaultpalette(); 

   for (i=0; i<16; i++) 
   { 
      printf("colors[%d] = %d\n", i, 
             pal->colors[i]); 
      getch(); 
   } 

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

函数名: getdisk 
功  能: 取当前磁盘驱动器号 
用  法: int getdisk(void); 
程序例: 

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

int main(void) 
{ 
   int disk; 

   disk = getdisk() + 'A'; 
   printf("The current drive is: %c\n", 
    disk); 
   return 0; 
} 
  
  
  

函数名: getdrivername 
功  能: 返回指向包含当前图形驱动程序名字的字符串指针 
用  法: char *getdrivename(void); 
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; 

/* stores the device driver name */ 
   char *drivername; 

/* 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));