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<tr> <td align=left height="40" valign=bottom align=left><small><a href="/">首页</a> > 编程技术 > C/C++ > 正文</small></td></tr><tr> <td width="100%" height="2" colspan="5" bgcolor="#D09F0D"><img src="/images/c.gif" width=1 height=1></td> </tr><tr> <td align=center height="40" valign=middle><font size=5><b>C语言库函数(P类字母)</b></font></td></tr><tr> <td align=center height="20"><font color=#999999><small>本文出自: 作者: (2001-10-25 07:00:01)</small></font></td></tr><td align=center><table border="0" width="700" cellspacing="0" cellpadding="0" align=center><tr><td valign=top><font color=#cccccc>
<br>函数名: parsfnm
<br>功 能: 分析文件名
<br>用 法: char *parsfnm (char *cmdline, struct fcb *fcbptr, int option);
<br>程序例:
<br>
<br>#include <process.h>
<br>#include <string.h>
<br>#include <stdio.h>
<br>#include <dos.h>
<br>
<br>int main(void)
<br>{
<br> char line[80];
<br> struct fcb blk;
<br>
<br> /* get file name */
<br> printf("Enter drive and file name (no path - ie. a:file.dat)\n");
<br> gets(line);
<br>
<br> /* put file name in fcb */
<br> if (parsfnm(line, &blk, 1) == NULL)
<br> printf("Error in parsfm call\n");
<br> else
<br> printf("Drive #%d Name: %11s\n", blk.fcb_drive, blk.fcb_name);
<br>
<br> return 0;
<br>}
<br>
<br>
<br>
<br>函数名: peek
<br>功 能: 检查存储单元
<br>用 法: int peek(int segment, unsigned offset);
<br>程序例:
<br>
<br>#include <stdio.h>
<br>#include <conio.h>
<br>#include <dos.h>
<br>
<br>int main(void)
<br>{
<br> int value = 0;
<br>
<br> printf("The current status of your keyboard is:\n");
<br> value = peek(0x0040, 0x0017);
<br> if (value & 1)
<br> printf("Right shift on\n");
<br> else
<br> printf("Right shift off\n");
<br>
<br> if (value & 2)
<br> printf("Left shift on\n");
<br> else
<br> printf("Left shift off\n");
<br>
<br> if (value & 4)
<br> printf("Control key on\n");
<br> else
<br> printf("Control key off\n");
<br>
<br> if (value & 8)
<br> printf("Alt key on\n");
<br> else
<br> printf("Alt key off\n");
<br>
<br> if (value & 16)
<br> printf("Scroll lock on\n");
<br> else
<br> printf("Scroll lock off\n");
<br>
<br> if (value & 32)
<br> printf("Num lock on\n");
<br> else
<br> printf("Num lock off\n");
<br>
<br> if (value & 64)
<br> printf("Caps lock on\n");
<br> else
<br> printf("Caps lock off\n");
<br>
<br> return 0;
<br>}
<br>
<br>
<br>
<br>函数名: peekb
<br>功 能: 检查存储单元
<br>用 法: char peekb (int segment, unsigned offset);
<br>程序例:
<br>
<br>#include <stdio.h>
<br>#include <conio.h>
<br>#include <dos.h>
<br>
<br>int main(void)
<br>{
<br> int value = 0;
<br>
<br> printf("The current status of your keyboard is:\n");
<br> value = peekb(0x0040, 0x0017);
<br> if (value & 1)
<br> printf("Right shift on\n");
<br> else
<br> printf("Right shift off\n");
<br>
<br> if (value & 2)
<br> printf("Left shift on\n");
<br> else
<br> printf("Left shift off\n");
<br>
<br> if (value & 4)
<br> printf("Control key on\n");
<br> else
<br> printf("Control key off\n");
<br>
<br> if (value & 8)
<br> printf("Alt key on\n");
<br> else
<br> printf("Alt key off\n");
<br>
<br> if (value & 16)
<br> printf("Scroll lock on\n");
<br> else
<br> printf("Scroll lock off\n");
<br>
<br> if (value & 32)
<br> printf("Num lock on\n");
<br> else
<br> printf("Num lock off\n");
<br>
<br> if (value & 64)
<br> printf("Caps lock on\n");
<br> else
<br> printf("Caps lock off\n");
<br>
<br> return 0;
<br>}
<br>
<br>
<br>
<br>函数名: perror
<br>功 能: 系统错误信息
<br>用 法: void perror(char *string);
<br>程序例:
<br>
<br>#include <stdio.h>
<br>
<br>int main(void)
<br>{
<br> FILE *fp;
<br>
<br> fp = fopen("perror.dat", "r");
<br> if (!fp)
<br> perror("Unable to open file for reading");
<br> return 0;
<br>}
<br>
<br>
<br>
<br>函数名: pieslice
<br>功 能: 绘制并填充一个扇形
<br>用 法: void far pieslice(int x, int stanle, int endangle, int radius);
<br>程序例:
<br>
<br>#include <graphics.h>
<br>#include <stdlib.h>
<br>#include <stdio.h>
<br>#include <conio.h>
<br>
<br>int main(void)
<br>{
<br> /* request auto detection */
<br> int gdriver = DETECT, gmode, errorcode;
<br> int midx, midy;
<br> int stangle = 45, endangle = 135, radius = 100;
<br>
<br> /* initialize graphics and local variables */
<br> initgraph(&gdriver, &gmode, "");
<br>
<br> /* read result of initialization */
<br> errorcode = graphresult();
<br> if (errorcode != grOk) /* an error occurred */
<br> {
<br> printf("Graphics error: %s\n", grapherrormsg(errorcode));
<br> printf("Press any key to halt:");
<br> getch();
<br> exit(1); /* terminate with an error code */
<br> }
<br>
<br> midx = getmaxx() / 2;
<br> midy = getmaxy() / 2;
<br>
<br> /* set fill style and draw a pie slice */
<br> setfillstyle(EMPTY_FILL, getmaxcolor());
<br> pieslice(midx, midy, stangle, endangle, radius);
<br>
<br> /* clean up */
<br> getch();
<br> closegraph();
<br> return 0;
<br>}
<br>
<br>
<br>
<br>函数名: poke
<br>功 能: 存值到一个给定存储单元
<br>用 法: void poke(int segment, int offset, int value);
<br>程序例:
<br>
<br>#include <dos.h>
<br>#include <conio.h>
<br>
<br>int main(void)
<br>{
<br> clrscr();
<br> cprintf("Make sure the scroll lock key is off and press any key\r\n");
<br> getch();
<br> poke(0x0000,0x0417,16);
<br> cprintf("The scroll lock is now on\r\n");
<br> return 0;
<br>}
<br>
<br>
<br>
<br>函数名: pokeb
<br>功 能: 存值到一个给定存储单元
<br>用 法: void pokeb(int segment, int offset, char value);
<br>程序例:
<br>
<br>#include <dos.h>
<br>#include <conio.h>
<br>
<br>int main(void)
<br>{
<br> clrscr();
<br> cprintf("Make sure the scroll lock key is off and press any key\r\n");
<br> getch();
<br> pokeb(0x0000,0x0417,16);
<br> cprintf("The scroll lock is now on\r\n");
<br> return 0;
<br>}
<br>
<br>
<br>
<br>函数名: poly
<br>功 能: 根据参数产生一个多项式
<br>用 法: double poly(double x, int n, double c[]);
<br>程序例:
<br>
<br>#include <stdio.h>
<br>#include <math.h>
<br>
<br>/* polynomial: x**3 - 2x**2 + 5x - 1 */
<br>
<br>int main(void)
<br>{
<br> double array[] = { -1.0, 5.0, -2.0, 1.0 };
<br> double result;
<br>
<br> result = poly(2.0, 3, array);
<br> printf("The polynomial: x**3 - 2.0x**2 + 5x - 1 at 2.0 is %lf\n",
<br> result);
<br> return 0;
<br>}
<br>
<br>
<br>
<br>函数名: pow
<br>功 能: 指数函数(x的y次方)
<br>用 法: double pow(double x, double y);
<br>程序例:
<br>
<br>#include <math.h>
<br>#include <stdio.h>
<br>
<br>int main(void)
<br>{
<br> double x = 2.0, y = 3.0;
<br>
<br> printf("%lf raised to %lf is %lf\n", x, y, pow(x, y));
<br> return 0;
<br>}
<br>
<br>
<br>函数名: pow10
<br>功 能: 指数函数(10的p次方)
<br>用 法: double pow10(int p);
<br>程序例:
<br>
<br>#include <math.h>
<br>#include <stdio.h>
<br>
<br>int main(void)
<br>{
<br> double p = 3.0;
<br>
<br> printf("Ten raised to %lf is %lf\n", p, pow10(p));
<br> return 0;
<br>}
<br>
<br>
<br>
<br>函数名: printf
<br>功 能: 产生格式化输出的函数
<br>用 法: int printf(char *format...);
<br>程序例:
<br>
<br>#include <stdio.h>
<br>#include <string.h>
<br>
<br>#define I 555
<br>#define R 5.5
<br>
<br>int main(void)
<br>{
<br> int i,j,k,l;
<br> char buf[7];
<br> char *prefix = buf;
<br> char tp[20];
<br> printf("prefix 6d 6o 8x 10.2e "
<br> "10.2f\n");
<br> strcpy(prefix,"%");
<br> for (i = 0; i < 2; i++)
<br> {
<br> for (j = 0; j < 2; j++)
<br> for (k = 0; k < 2; k++)
<br> for (l = 0; l < 2; l++)
<br> {
<br> if (i==0) strcat(prefix,"-");
<br> if (j==0) strcat(prefix,"+");
<br> if (k==0) strcat(prefix,"#");
<br> if (l==0) strcat(prefix,"0");
<br> printf("%5s |",prefix);
<br> strcpy(tp,prefix);
<br> strcat(tp,"6d |");
<br> printf(tp,I);
<br> strcpy(tp,"");
<br> strcpy(tp,prefix);
<br> strcat(tp,"6o |");
<br> printf(tp,I);
<br> strcpy(tp,"");
<br> strcpy(tp,prefix);
<br> strcat(tp,"8x |");
<br> printf(tp,I);
<br> strcpy(tp,"");
<br> strcpy(tp,prefix);
<br> strcat(tp,"10.2e |");
<br> printf(tp,R);
<br> strcpy(tp,prefix);
<br> strcat(tp,"10.2f |");
<br> printf(tp,R);
<br> printf(" \n");
<br> strcpy(prefix,"%");
<br> }
<br> }
<br> return 0;
<br>}
<br>
<br>
<br>
<br>函数名: putc
<br>功 能: 输出一字符到指定流中
<br>用 法: int putc(int ch, FILE *stream);
<br>程序例:
<br>
<br>#include <stdio.h>
<br>
<br>int main(void)
<br>{
<br> char msg[] = "Hello world\n";
<br> int i = 0;
<br>
<br> while (msg[i])
<br> putc(msg[i++], stdout);
<br> return 0;
<br>}
<br>
<br>
<br>
<br>函数名: putch
<br>功 能: 输出字符到控制台
<br>用 法: int putch(int ch);
<br>程序例:
<br>
<br>#include <stdio.h>
<br>#include <conio.h>
<br>
<br>int main(void)
<br>{
<br> char ch = 0;
<br>
<br> printf("Input a string:");
<br> while ((ch != '\r'))
<br> {
<br> ch = getch();
<br> putch(ch);
<br> }
<br> return 0;
<br>}
<br>
<br>
<br>
<br>函数名: putchar
<br>功 能: 在stdout上输出字符
<br>用 法: int putchar(int ch);
<br>程序例:
<br>
<br>#include <stdio.h>
<br>
<br>/* define some box-drawing characters */
<br>#define LEFT_TOP 0xDA
<br>#define RIGHT_TOP 0xBF
<br>#define HORIZ 0xC4
<br>#define VERT 0xB3
<br>#define LEFT_BOT 0xC0
<br>#define RIGHT_BOT 0xD9
<br>
<br>int main(void)
<br>{
<br> char i, j;
<br>
<br> /* draw the top of the box */
<br> putchar(LEFT_TOP);
<br> for (i=0; i<10; i++)
<br> putchar(HORIZ);
<br> putchar(RIGHT_TOP);
<br> putchar('\n');
<br>
<br> /* draw the middle */
<br> for (i=0; i<4; i++)
<br> {
<br> putchar(VERT);
<br> for (j=0; j<10; j++)
<br> putchar(' ');
<br> putchar(VERT);
<br> putchar('\n');
<br> }
<br>
<br> /* draw the bottom */
<br> putchar(LEFT_BOT);
<br> for (i=0; i<10; i++)
<br> putchar(HORIZ);
<br> putchar(RIGHT_BOT);
<br> putchar('\n');
<br>
<br> return 0;
<br>}
<br>
<br>
<br>
<br>函数名: putenv
<br>功 能: 把字符串加到当前环境中
<br>用 法: int putenv(char *envvar);
<br>程序例:
<br>
<br>#include <stdio.h>
<br>#include <stdlib.h>
<br>#include <alloc.h>
<br>#include <string.h>
<br>#include <dos.h>
<br>
<br>int main(void)
<br>{
<br> char *path, *ptr;
<br> int i = 0;
<br>
<br> /* get the current path environment */
<br> ptr = getenv("PATH");
<br>
<br> /* set up new path */
<br> path = malloc(strlen(ptr)+15);
<br> strcpy(path,"PATH=");
<br> strcat(path,ptr);
<br> strcat(path,";c:\\temp");
<br>
<br> /* replace the current path and display current environment */
<br> putenv(path);
<br> while (environ[i])
<br> printf("%s\n",environ[i++]);
<br>
<br> return 0;
<br>}
<br>
<br>
<br>
<br>函数名: putimage
<br>功 能: 在屏幕上输出一个位图
<br>用 法: void far putimage(int x, int y, void far *bitmap, int op);
<br>程序例:
<br>
<br>#include <graphics.h>
<br>#include <stdlib.h>
<br>#include <stdio.h>
<br>#include <conio.h>
<br>
<br>#define ARROW_SIZE 10
<br>
<br>void draw_arrow(int x, int y);
<br>
<br>int main(void)
<br>{
<br> /* request autodetection */
<br> int gdriver = DETECT, gmode, errorcode;
<br> void *arrow;
<br> int x, y, maxx;
<br> unsigned int size;
<br>
<br> /* initialize graphics and local variables */
<br> initgraph(&gdriver, &gmode, "");
<br>
<br> /* read result of initialization */
<br> errorcode = graphresult();
<br> if (errorcode != grOk) /* an error occurred */
<br> {
<br> printf("Graphics error: %s\n", grapherrormsg(errorcode));
<br> printf("Press any key to halt:");
<br> getch();
<br> exit(1); /* terminate with an error code */
<br> }
<br>
<br> maxx = getmaxx();
<br> x = 0;
<br> y = getmaxy() / 2;
<br>
<br> /* draw the image to be grabbed */
<br> draw_arrow(x, y);
<br>
<br> /* calculate the size of the image */
<br> size = imagesize(x, y-ARROW_SIZE, x+(4*ARROW_SIZE), y+ARROW_SIZE);
<br>
<br> /* allocate memory to hold the image */
<br> arrow = malloc(size);
<br>
<br> /* grab the image */
<br> getimage(x, y-ARROW_SIZE, x+(4*ARROW_SIZE), y+ARROW_SIZE, arrow);
<br>
<br> /* repeat until a key is pressed */
<br> while (!kbhit())
<br> {
<br> /* erase old image */
<br> putimage(x, y-ARROW_SIZE, arrow, XOR_PUT);
<br>
<br> x += ARROW_SIZE;
<br> if (x >= maxx)
<br> x = 0;
<br>
<br> /* plot new image */
<br> putimage(x, y-ARROW_SIZE, arrow, XOR_PUT);
<br> }
<br>
<br> /* clean up */
<br> free(arrow);
<br> closegraph();
<br> return 0;
<br>}
<br>
<br>void draw_arrow(int x, int y)
<br>{
<br> /* draw an arrow on the screen */
<br> moveto(x, y);
<br> linerel(4*ARROW_SIZE, 0);
<br> linerel(-2*ARROW_SIZE, -1*ARROW_SIZE);
<br> linerel(0, 2*ARROW_SIZE);
<br> linerel(2*ARROW_SIZE, -1*ARROW_SIZE);
<br>}
<br>
<br>
<br>
<br>函数名: putpixel
<br>功 能: 在指定位置画一像素
<br>用 法: void far putpixel (int x, int y, int pixelcolor);
<br>程序例:
<br>
<br>#include <graphics.h>
<br>#include <stdlib.h>
<br>#include <stdio.h>
<br>#include <conio.h>
<br>#include <dos.h>
<br>
<br>#define PIXEL_COUNT 1000
<br>#define DELAY_TIME 100 /* in milliseconds */
<br>
<br>int main(void)
<br>{
<br> /* request autodetection */
<br> int gdriver = DETECT, gmode, errorcode;
<br> int i, x, y, color, maxx, maxy, maxcolor, seed;
<br>
<br> /* initialize graphics and local variables */
<br> initgraph(&gdriver, &gmode, "");
<br>
<br> /* read result of initialization */
<br> errorcode = graphresult();
<br> if (errorcode != grOk) /* an error occurred */
<br> {
<br> printf("Graphics error: %s\n", grapherrormsg(errorcode));
<br> printf("Press any key to halt:");
<br> getch();
<br> exit(1); /* terminate with an error code */
<br> }
<br>
<br> maxx = getmaxx() + 1;
<br> maxy = getmaxy() + 1;
<br> maxcolor = getmaxcolor() + 1;
<br>
<br> while (!kbhit())
<br> {
<br> /* seed the random number generator */
<br> seed = random(32767);
<br> srand(seed);
<br> for (i=0; i<PIXEL_COUNT; i++)
<br> {
<br> x = random(maxx);
<br> y = random(maxy);
<br> color = random(maxcolor);
<br> putpixel(x, y, color);
<br> }
<br>
<br> delay(DELAY_TIME);
<br> srand(seed);
<br> for (i=0; i<PIXEL_COUNT; i++)
<br> {
<br> x = random(maxx);
<br> y = random(maxy);
<br> color = random(maxcolor);
<br> if (color == getpixel(x, y))
<br> putpixel(x, y, 0);
<br> }
<br> }
<br>
<br> /* clean up */
<br> getch();
<br> closegraph();
<br> return 0;
<br>}
<br>
<br>
<br>
<br>函数名: puts
<br>功 能: 送一字符串到流中
<br>用 法: int puts(char *string);
<br>程序例:
<br>
<br>#include <stdio.h>
<br>int main(void)
<br>{
<br> char string[] = "This is an example output string\n";
<br>
<br> puts(string);
<br> return 0;
<br>}
<br>
<br>
<br>
<br>函数名: puttext
<br>功 能: 将文本从存储区拷贝到屏幕
<br>用 法: int puttext(int left, int top, int right, int bottom, void *source);
<br>程序例:
<br>
<br>#include <conio.h>
<br>int main(void)
<br>{
<br> char buffer[512];
<br>
<br> /* put some text to the console */
<br> clrscr();
<br> gotoxy(20, 12);
<br> cprintf("This is a test. Press any key to continue ...");
<br> getch();
<br>
<br> /* grab screen contents */
<br> gettext(20, 12, 36, 21,buffer);
<br> clrscr();
<br>
<br> /* put selected characters back to the screen */
<br> gotoxy(20, 12);
<br> puttext(20, 12, 36, 21, buffer);
<br> getch();
<br>
<br> return 0;
<br>}
<br>
<br>
<br>
<br>函数名: putw
<br>功 能: 把一字符或字送到流中
<br>用 法: int putw(int w, FILE *stream);
<br>程序例:
<br>
<br>#include <stdio.h>
<br>#include <stdlib.h>
<br>
<br>#define FNAME "test.$$$"
<br>
<br>int main(void)
<br>{
<br> FILE *fp;
<br> int word;
<br>
<br> /* place the word in a file */
<br> fp = fopen(FNAME, "wb");
<br> if (fp == NULL)
<br> {
<br> printf("Error opening file %s\n", FNAME);
<br> exit(1);
<br> }
<br>
<br> word = 94;
<br> putw(word,fp);
<br> if (ferror(fp))
<br> printf("Error writing to file\n");
<br> else
<br> printf("Successful write\n");
<br> fclose(fp);
<br>
<br> /* reopen the file */
<br> fp = fopen(FNAME, "rb");
<br> if (fp == NULL)
<br> {
<br> printf("Error opening file %s\n", FNAME);
<br> exit(1);
<br> }
<br>
<br> /* extract the word */
<br> word = getw(fp);
<br> if (ferror(fp))
<br> printf("Error reading file\n");
<br> else
<br> printf("Successful read: word = %d\n", word);
<br>
<br> /* clean up */
<br> fclose(fp);
<br> unlink(FNAME);
<br>
<br> return 0;
<br>}
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