c_info.txt

这是一个unix 系统下的 C 语言函数大全的电子文章。

      函数名: clearerr 
      功 能: 复位错误标志 
      用 法:void clearerr(FILE *stream); 
      程序例: 

      #include <stdio.h> 

      int main(void) 
      { 
      FILE *fp; 
      char ch; 

      /* open a file for writing */ 
      fp = fopen("DUMMY.FIL", "w"); 

      /* force an error condition by attempting to read */ 
      ch = fgetc(fp); 
      printf("%c\n",ch); 

      if (ferror(fp)) 
      { 
      /* display an error message */ 
      printf("Error reading from DUMMY.FIL\n"); 

      /* reset the error and EOF indicators */ 
      clearerr(fp); 
      } 

      fclose(fp); 
      return 0; 
      } 




      函数名: clearviewport 
      功 能: 清除图形视区 
      用 法: void far clearviewport(void); 
      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; 
      int 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 */ 
      } 

      setcolor(getmaxcolor()); 
      ht = textheight("W"); 

      /* 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 messages */ 
      outtextxy(0, 0, "* <-- (0, 0) in smaller viewport"); 
      outtextxy(0, 2*ht, "Press any key to clear viewport:"); 

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

      /* clear the viewport */ 
      clearviewport(); 

      /* output another message */ 
      outtextxy(0, 0, "Press any key to quit:"); 

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




      函数名: _close, close 
      功 能: 关闭文件句柄 
      用 法: int close(int handle); 
      程序例: 

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

      main() 
      { 
      int handle; 
      char buf[11] = "0123456789"; 

      /* create a file containing 10 bytes */ 
      handle = open("NEW.FIL", O_CREAT); 
      if (handle > -1) 
      { 
      write(handle, buf, strlen(buf)); 

      /* close the file */ 
      close(handle); 
      } 
      else 
      { 
      printf("Error opening file\n"); 
      } 
      return 0; 
      } 




      函数名: clock 
      功 能: 确定处理器时间 
      用 法: clock_t clock(void); 
      程序例: 

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

      int main(void) 
      { 
      clock_t start, end; 
      start = clock(); 

      delay(2000); 

      end = clock(); 
      printf("The time was: %f\n", (end - start) / CLK_TCK); 

      return 0; 
      } 




      函数名: closegraph 
      功 能: 关闭图形系统 
      用 法: void far closegraph(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 x, y; 

      /* initialize graphics mode */ 
      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; 

      /* output a message */ 
      settextjustify(CENTER_TEXT, CENTER_TEXT); 
      outtextxy(x, y, "Press a key to close the graphics system:"); 

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

      /* closes down the graphics system */ 
      closegraph(); 

      printf("We're now back in text mode.\n"); 
      printf("Press any key to halt:"); 
      getch(); 
      return 0; 
      } 




      函数名: clreol 
      功 能: 在文本窗口中清除字符到行末 
      用 法: void clreol(void); 
      程序例: 

      #include <conio.h> 

      int main(void) 

      { 
      clrscr(); 
      cprintf("The function CLREOL clears all characters from 
      the\r\n"); 
      cprintf("cursor position to the end of the line within 
      the\r\n"); 
      cprintf("current text window, without moving the 
      cursor.\r\n"); 
      cprintf("Press any key to continue . . ."); 
      gotoxy(14, 4); 
      getch(); 

      clreol(); 
      getch(); 

      return 0; 
      } 




      函数名: clrscr 
      功 能: 清除文本模式窗口 
      用 法: void clrscr(void); 
      程序例: 

      #include <conio.h> 

      int main(void) 
      { 
      int i; 

      clrscr(); 
      for (i = 0; i < 20; i++) 
      cprintf("%d\r\n", i); 
      cprintf("\r\nPress any key to clear screen"); 
      getch(); 

      clrscr(); 
      cprintf("The screen has been cleared!"); 
      getch(); 

      return 0; 
      } 




      函数名: coreleft 
      功 能: 返回未使用内存的大小 
      用 法: unsigned coreleft(void); 
      程序例: 

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

      int main(void) 
      { 
      printf("The difference between the highest allocated block 
      and\n"); 
      printf("the top of the heap is: %lu bytes\n", (unsigned long) 
      coreleft()); 

      return 0; 
      } 


      函数名: cos 
      功 能: 余弦函数 
      用 法: double cos(double x); 
      程序例: 

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

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

      result = cos(x); 
      printf("The cosine of %lf is %lf\n", x, result); 
      return 0; 
      } 




      函数名: cosh 
      功 能: 双曲余弦函数 
      用 法: dluble cosh(double x); 
      程序例: 

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

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

      result = cosh(x); 
      printf("The hyperboic cosine of %lf is %lf\n", x, result); 
      return 0; 
      } 




      函数名: country 
      功 能: 返回与国家有关的信息 
      用 法: struct COUNTRY *country(int countrycode, struct country 
      *country); 
      程序例: 

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

      #define USA 0 

      int main(void) 
      { 
      struct COUNTRY country_info; 

      country(USA, &country_info); 
      printf("The currency symbol for the USA is: %s\n", 
      country_info.co_curr); 
      return 0; 
      } 




      函数名: cprintf 
      功 能: 送格式化输出至屏幕 
      用 法: int cprintf(const char *format[, argument, ...]); 
      程序例: 

      #include <conio.h> 

      int main(void) 
      { 
      /* clear the screen */ 
      clrscr(); 

      /* create a text window */ 
      window(10, 10, 80, 25); 

      /* output some text in the window */ 
      cprintf("Hello world\r\n"); 

      /* wait for a key */ 
      getch(); 
      return 0; 
      } 




      函数名: cputs 
      功 能: 写字符到屏幕 
      用 法: void cputs(const char *string); 
      程序例: 

      #include <conio.h> 

      int main(void) 
      { 
      /* clear the screen */ 
      clrscr(); 

      /* create a text window */ 
      window(10, 10, 80, 25); 

      /* output some text in the window */ 
      cputs("This is within the window\r\n"); 

      /* wait for a key */ 
      getch(); 
      return 0; 
      } 




      函数名: _creat creat 
      功 能: 创建一个新文件或重写一个已存在的文件 
      用 法: int creat (const char *filename, int permiss); 
      程序例: 

      #include <sys\stat.h> 
      #include <string.h> 
      #include <fcntl.h> 
      #include <io.h> 

      int main(void) 
      { 
      int handle; 
      char buf[11] = "0123456789"; 

      /* change the default file mode from text to binary */ 
      _fmode = O_BINARY; 

      /* create a binary file for reading and writing */ 
      handle = creat("DUMMY.FIL", S_IREAD | S_IWRITE); 

      /* write 10 bytes to the file */ 
      write(handle, buf, strlen(buf)); 

      /* close the file */ 
      close(handle); 
      return 0; 
      } 


      函数名: creatnew 
      功 能: 创建一个新文件 
      用 法: int creatnew(const char *filename, int attrib); 
      程序例: 

      #include <string.h> 
      #include <stdio.h> 
      #include <errno.h> 
      #include <dos.h> 
      #include <io.h> 

      int main(void) 
      { 
      int handle; 
      char buf[11] = "0123456789"; 

      /* attempt to create a file that doesn't already exist */ 
      handle = creatnew("DUMMY.FIL", 0); 

      if (handle == -1) 
      printf("DUMMY.FIL already exists.\n"); 
      else 
      { 
      printf("DUMMY.FIL successfully created.\n"); 
      write(handle, buf, strlen(buf)); 
      close(handle); 
      } 
      return 0; 
      } 




      函数名: creattemp 
      功 能: 创建一个新文件或重写一个已存在的文件 
      用 法: int creattemp(const char *filename, int attrib); 
      程序例: 

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

      int main(void) 
      { 
      int handle; 
      char pathname[128]; 

      strcpy(pathname, "\\"); 

      /* create a unique file in the root directory */ 
      handle = creattemp(pathname, 0); 

      printf("%s was the unique file created.\n", pathname); 
      close(handle); 
      return 0; 
      } 




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

      #include <conio.h> 

      int main(void) 
      { 
      char string[80]; 

      /* clear the screen */ 
      clrscr(); 

      /* Prompt the user for input */ 
      cprintf("Enter a string with no spaces:"); 

      /* read the input */ 
      cscanf("%s", string); 

      /* display what was read */ 
      cprintf("\r\nThe string entered is: %s", string); 
      return 0; 
      } 




      函数名: ctime 
      功 能: 把日期和时间转换为字符串 
      用 法: char *ctime(const time_t *time); 
      程序例: 

      #include <stdio.h> 
      #include <time.h> 

      int main(void) 
      { 
      time_t t; 

      time(&t); 
      printf("Today's date and time: %s\n", ctime(&t)); 
      return 0; 
      } 




      函数名: ctrlbrk 
      功 能: 设置Ctrl-Break处理程序 
      用 法: void ctrlbrk(*fptr)(void); 
      程序例: 

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

      #define ABORT 0 

      int c_break(void) 
      { 
      printf("Control-Break pressed. Program aborting ...\n"); 
      return (ABORT); 
      } 

      int main(void) 
      { 
      ctrlbrk(c_break); 
      for(;;) 
      { 
      printf("Looping... Press <Ctrl-Break> to quit:\n"); 
      } 
      return 0; 
      } 
      函数名: delay 
      功 能: 将程序的执行暂停一段时间(毫秒) 
      用 法: void delay(unsigned milliseconds); 
      程序例: 
      /* Emits a 440-Hz tone for 500 milliseconds */ 
      #include <dos.h> 
      int main(void) 
      { 
      sound(440); 
      delay(500); 
      nosound(); 

      return 0; 
      } 



      函数名: delline 
      功 能: 在文本窗口中删去一行 
      用 法: void delline(void); 
      程序例: 

      #include <conio.h> 

      int main(void) 
      { 
      clrscr(); 
      cprintf("The function DELLINE deletes \ 
      the line containing the\r\n"); 
      cprintf("cursor and moves all lines \ 
      below it one line up.\r\n"); 
      cprintf("DELLINE operates within the \ 
      currently active text\r\n"); 
      cprintf("window. Press any key to \ 
      continue . . ."); 
      gotoxy(1,2); /* Move the cursor to the 
      second line and first column */ 
      getch(); 

      delline(); 
      getch(); 

      return 0;