{  
   char msg[] = "Hello world\n";  
   int i = 0;  

   while (msg[i])  
      putc(msg[i++], stdout);  
   return 0;  
}  
   
   

函數名: putch  
功  能: 輸出字符到控制臺  
用  法: int putch(int ch);  
程序例:  

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

int main(void)  
{  
   char ch = 0;  

   printf("Input a string:");  
   while ((ch != '\r'))  
   {  
      ch = getch();  
      putch(ch);  
   }  
   return 0;  
}  
   
   

函數名: putchar  
功  能: 在stdout上輸出字符  
用  法: int putchar(int ch);  
程序例:  

#include <stdio.h>  

/* define some box-drawing characters */  
#define LEFT_TOP  0xDA  
#define RIGHT_TOP 0xBF  
#define HORIZ     0xC4  
#define VERT      0xB3  
#define LEFT_BOT  0xC0  
#define RIGHT_BOT 0xD9  

int main(void)  
{  
   char i, j;  

   /* draw the top of the box */  
   putchar(LEFT_TOP);  
   for (i=0; i<10; i++)  
      putchar(HORIZ);  
   putchar(RIGHT_TOP);  
   putchar('\n');  

   /* draw the middle */  
   for (i=0; i<4; i++)  
   {  
      putchar(VERT);  
      for (j=0; j<10; j++)  
         putchar(' ');  
      putchar(VERT);  
      putchar('\n');  
   }  

   /* draw the bottom */  
   putchar(LEFT_BOT);  
   for (i=0; i<10; i++)  
      putchar(HORIZ);  
   putchar(RIGHT_BOT);  
   putchar('\n');  

   return 0;  
}  
   
   

函數名: putenv  
功  能: 把字符串加到當前環境中  
用  法: int putenv(char *envvar);  
程序例:  

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

int main(void)  
{  
   char *path, *ptr;  
   int i = 0;  

   /* get the current path environment */  
   ptr = getenv("PATH");  

   /* set up new path */  
   path = malloc(strlen(ptr)+15);  
   strcpy(path,"PATH=");  
   strcat(path,ptr);  
   strcat(path,";c:\\temp");  

   /* replace the current path and display current environment */  
   putenv(path);  
   while (environ[i])  
       printf("%s\n",environ[i++]);  

   return 0;  
}  
   
   

函數名: putimage  
功  能: 在屏幕上輸出一個位圖  
用  法: void far putimage(int x, int y, void far *bitmap, int op);  
程序例:  

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

#define ARROW_SIZE 10  

void draw_arrow(int x, int y);  

int main(void)  
{  
   /* request autodetection */  
   int gdriver = DETECT, gmode, errorcode;  
   void *arrow;  
   int x, y, maxx;  
   unsigned int size;  

   /* 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 */  
   }  

   maxx = getmaxx();  
   x = 0;  
   y = getmaxy() / 2;  

   /* draw the image to be grabbed */  
   draw_arrow(x, y);  

   /* calculate the size of the image */  
   size = imagesize(x, y-ARROW_SIZE, x+(4*ARROW_SIZE), y+ARROW_SIZE);  

   /* allocate memory to hold the image */  
   arrow = malloc(size);  

   /* grab the image */  
   getimage(x, y-ARROW_SIZE, x+(4*ARROW_SIZE), y+ARROW_SIZE, arrow);  

   /* repeat until a key is pressed */  
   while (!kbhit())  
   {  
      /* erase old image */  
      putimage(x, y-ARROW_SIZE, arrow, XOR_PUT);  

      x += ARROW_SIZE;  
      if (x >= maxx)  
          x = 0;  

      /* plot new image */  
      putimage(x, y-ARROW_SIZE, arrow, XOR_PUT);  
   }  

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

void draw_arrow(int x, int y)  
{  
   /* draw an arrow on the screen */  
   moveto(x, y);  
   linerel(4*ARROW_SIZE, 0);  
   linerel(-2*ARROW_SIZE, -1*ARROW_SIZE);  
   linerel(0, 2*ARROW_SIZE);  
   linerel(2*ARROW_SIZE, -1*ARROW_SIZE);  
}  
   
   

函數名: putpixel  
功  能: 在指定位置畫一像素  
用  法: void far putpixel (int x, int y, int pixelcolor);  
程序例:  

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

#define PIXEL_COUNT 1000  
#define DELAY_TIME  100  /* in milliseconds */  

int main(void)  
{  
   /* request autodetection */  
   int gdriver = DETECT, gmode, errorcode;  
   int i, x, y, color, maxx, maxy, maxcolor, seed;  

   /* 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 */  
   }  

   maxx = getmaxx() + 1;  
   maxy = getmaxy() + 1;  
   maxcolor = getmaxcolor() + 1;  

   while (!kbhit())  
   {  
      /* seed the random number generator */  
      seed = random(32767);  
      srand(seed);  
      for (i=0; i<PIXEL_COUNT; i++)  
      {  
  x = random(maxx);  
         y = random(maxy);  
         color = random(maxcolor);  
         putpixel(x, y, color);  
      }  

      delay(DELAY_TIME);  
      srand(seed);  
      for (i=0; i<PIXEL_COUNT; i++)  
      {  
  x = random(maxx);  
  y = random(maxy);  
  color = random(maxcolor);  
  if (color == getpixel(x, y))  
     putpixel(x, y, 0);  
      }  
   }  

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

函數名: puts  
功  能: 送一字符串到流中  
用  法: int puts(char *string);  
程序例:  

#include <stdio.h>  
int main(void)  
{  
   char string[] = "This is an example output string\n";  

   puts(string);  
   return 0;  
}  
   
   

函數名: puttext  
功  能: 將文本從存儲區拷貝到屏幕  
用  法: int puttext(int left, int top, int right, int bottom, void *source);  
程序例:  

#include <conio.h>  
int main(void)  
{  
   char buffer[512];  

   /* put some text to the console */  
   clrscr();  
   gotoxy(20, 12);  
   cprintf("This is a test.  Press any key to continue ...");  
   getch();  

   /* grab screen contents */  
   gettext(20, 12, 36, 21,buffer);  
   clrscr();  

   /* put selected characters back to the screen */  
   gotoxy(20, 12);  
   puttext(20, 12, 36, 21, buffer);  
   getch();  

   return 0;  
}  
   
   

函數名: putw  
功  能: 把一字符或字送到流中  
用  法: int putw(int w, FILE *stream);  
程序例:  

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

#define FNAME "test.$$$"  

int main(void)  
{  
   FILE *fp;  
   int word;  

   /* place the word in a file */  
   fp = fopen(FNAME, "wb");  
   if (fp == NULL)  
   {  
      printf("Error opening file %s\n", FNAME);  
      exit(1);  
   }  

   word = 94;  
   putw(word,fp);  
   if (ferror(fp))  
       printf("Error writing to file\n");  
   else  
       printf("Successful write\n");  
   fclose(fp);  

   /* reopen the file */  
   fp = fopen(FNAME, "rb");  
   if (fp == NULL)  
   {  
      printf("Error opening file %s\n", FNAME);  
      exit(1);  
   }  

   /* extract the word */  
   word = getw(fp);  
   if (ferror(fp))  
       printf("Error reading file\n");  
   else  
       printf("Successful read: word = %d\n", word);  

   /* clean up */  
   fclose(fp);  
   unlink(FNAME);  

   return 0;  
}