C語言庫函數 (C類字母)

[ 發表日期:2002-1-4 9:28:46 ]

函數名: cabs

功 能: 計算複數的絕對值

用 法: double cabs(strUCt complex z);

程序例:

#include <stdio.h>

#include <math.h>

int main(void)

{

struct complex z;

double val;

z.x = 2.0;

z.y = 1.0;

val = cabs(z);

printf("The absolute value of %.2lfi %.2lfj is %.2lf", z.x, z.y, val);

return 0;

}

函數名: calloc

功 能: 分配主存儲器

用 法: void *calloc(size_t nelem, size_t elsize);

程序例:

#include <stdio.h>

#include <alloc.h>

int main(void)

{

char *str = NULL;

/* allocate memory for string */

str = calloc(10, sizeof(char));

/* copy "Hello" into string */

strcpy(str, "Hello");

/* display string */

printf("String is %s\n", str);

/* free memory */

free(str);

return 0;

}

函數名: ceil

功 能: 向上舍入

用 法: double ceil(double x);

程序例:

#include <math.h>

#include <stdio.h>

int main(void)

{

double number = 123.54;

double down, up;

down = floor(number);

up = ceil(number);

printf("original number %5.2lf\n", number);

printf("number rounded down %5.2lf\n", down);

printf("number rounded up %5.2lf\n", up);

return 0;

}

函數名: cgets

功 能: 從控制台讀字符串

用 法: char *cgets(char *str);

程序例:

#include <stdio.h>

#include <conio.h>

int main(void)

{

char buffer[83];

char *p;

/* There's space for 80 characters plus the NULL terminator */

buffer[0] = 81;

printf("Input some chars:");

p = cgets(buffer);

printf("\ncgets read %d characters: \"%s\"\n", buffer[1], p);

printf("The returned pointer is %p, buffer[0] is at %p\n", p, &buffer);

/* Leave room for 5 characters plus the NULL terminator */

buffer[0] = 6;

printf("Input some chars:");

p = cgets(buffer);

printf("\ncgets read %d characters: \"%s\"\n", buffer[1], p);

printf("The returned pointer is %p, buffer[0] is at %p\n", p, &buffer);

return 0;

}

函數名: chdir

功 能: 改變工作目錄

用 法: int chdir(const char *path);

程序例:

#include <stdio.h>

#include <stdlib.h>

#include <dir.h>

char old_dir[MAXDIR];

char new_dir[MAXDIR];

int main(void)

{

if (getcurdir(0, old_dir))

{

perror("getcurdir()");

exit(1);

}

printf("Current Directory is: \\%s\n", old_dir);

if (chdir("\\"))

{

perror("chdir()");

exit(1);

}

if (getcurdir(0, new_dir))

{

perror("getcurdir()");

exit(1);

}

printf("Current directory is now: \\%s\n", new_dir);

printf("\nChanging back to orignal directory: \\%s\n", old_dir);

if (chdir(old_dir))

{

perror("chdir()");

exit(1);

}

return 0;

}

函數名: _chmod, chmod

功 能: 改變文件的訪問方式

用 法: int chmod(const char *filename, int permiss);

程序例:

#include <sys\stat.h>

#include <stdio.h>

#include <io.h>

void make_read_only(char *filename);

int main(void)

{

make_read_only("NOTEXIST.FIL");

make_read_only("MYFILE.FIL");

return 0;

}

void make_read_only(char *filename)

{

int stat;

stat = chmod(filename, S_IREAD);

if (stat)

printf("Couldn't make %s read-only\n", filename);

else

printf("Made %s read-only\n", filename);

}

函數名: chsize

功 能: 改變文件大小

用 法: int chsize(int handle, long size);

程序例:

#include <string.h>

#include <fcntl.h>

#include <io.h>

int main(void)

{

int handle;

char buf[11] = "0123456789";

/* create text file containing 10 bytes */

handle = open("DUMMY.FIL", O_CREAT);

write(handle, buf, strlen(buf));

/* truncate the file to 5 bytes in size */

chsize(handle, 5);

/* close the file */

close(handle);

return 0;

}

函數名: circle

功 能: 在給定半徑以(x, y)爲圓心畫圓

用 法: void far circle(int x, int y, int radius);

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;

int radius = 100;

/* 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());

/* draw the circle */

circle(midx, midy, radius);

/* clean up */

getch();

closegraph();

return 0;

}

函數名: cleardevice

功 能: 清除圖形屏幕

用 法: void far cleardevice(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 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());

/* for centering screen messages */

settextjustify(CENTER_TEXT, CENTER_TEXT);

/* output a message to the screen */

outtextxy(midx, midy, "press any key to clear the screen:");

/* wait for a key */

getch();

/* clear the screen */

cleardevice();

/* output another message */

outtextxy(midx, midy, "press any key to quit:");

/* clean up */

getch();

closegraph();

return 0;

}

函數名: clearerr

功 能: 複位錯誤標志

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;

}

函數名: clearviewport

功 能: 清除圖形視區

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;

}

函數名: _close, close

功 能: 關閉文件句柄

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;

}

函數名: clock

功 能: 確定處理器時間

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;

}

函數名: closegraph

功 能: 關閉圖形系統

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;

}

函數名: 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;

}

函數名: 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;

}

函數名: coreleft

功 能: 返回未使用內存的大小

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;

}

函數名: cos

功 能: 余弦函數

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;

}

函數名: cosh

功 能: 雙曲余弦函數

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;

}

函數名: country

功 能: 返回與國家有關的信息

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;

}

函數名: cprintf

功 能: 送格式化輸出至屏幕

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;

}

函數名: cputs

功 能: 寫字符到屏幕

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;

}

函數名: _creat creat

功 能: 創建一個新文件或重寫一個已存在的文件

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;

}

函數名: creatnew

功 能: 創建一個新文件

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;

}

函數名: creattemp

功 能: 創建一個新文件或重寫一個已存在的文件

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;

}

函數名: cscanf

功 能: 從控制台執行格式化輸入

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;

}

函數名: ctime

功 能: 把日期和時間轉換爲字符串

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;

}

函數名: ctrlbrk

功 能: 設置Ctrl-Break處理程序

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;

}

· 把年齡相仿的獅虎熊放一起,誰更厲害?結果出人意料

很多人都想知道獅子、老虎和熊打起來誰最厲害,于是便有好事之人把這三種動物關在一起...

· 湖北宜昌三峽壩區水面驚現神秘動物

近日,湖北宜昌,一段視頻在當地熱傳:有網友在三峽壩區拍到神秘動物,體型碩大數米長...

· 什麽是語段?語段的類型以及和句群、段落的區別與聯系是什麽?

句群是最高級的語言單位。 段落(自然段)是章法單位...

 
C語言庫函數 (C類字母)
  [ 發表日期:2002-1-4 9:28:46 ] 函數名: cabs 功 能: 計算複數的絕對值 用 法: double cabs(strUCt complex z); 程序例: #include <stdio.h> #include <math.h> int main(void) { struct complex z...查看完整版>>C語言庫函數 (C類字母)
 
C語言庫函數 (B類字母)
[ 發表日期:2002-1-4 9:28:46 ] 函數名: bar 功 能: 畫一個二維條形圖 用 法: void far bar(int left, int top, int right, int bottom); 程序例: #include <graphics.h> #include <stdlib.h> #include...查看完整版>>C語言庫函數 (B類字母)
 
C語言庫函數(W類字母)
函數名: wherex功 能: 返回窗口內水平光標位置用 法: int wherex(void);程序例: #include <conio.h> int main(void){ clrscr(); gotoxy(10,10); cprintf("Current location is X: %d Y: %d\r\n", whe...查看完整版>>C語言庫函數(W類字母)
 
C語言庫函數(S類字母)
函數名: sbrk 功 能: 改變數據段空間位置 用 法: char *sbrk(int incr); 程序例: #include <stdio.h> #include <alloc.h> int main(void) { printf("Changing allocation with sbrk()\n"); prin...查看完整版>>C語言庫函數(S類字母)
 
C語言庫函數(S類字母)-2
  函數名: setjmp 功 能: 非局部轉移 用 法: int setjmp(jmp_buf env); 程序例: #include <stdio.h> #include <process.h> #include <setjmp.h> void subroutine(void); jmp_buf jumper; int ...查看完整版>>C語言庫函數(S類字母)-2