couble fmod (double x, double y); <?xml:namespace prefix="o" ns="urn:schemas-microsoft-com:office:office"?>
返回x对y的模,即x/y的余数。
void fnmerge(char *path,const char *drive,const char *dir,const char *name,const char *ext);
由给定的盘区路径文件名扩展名等组成部分建立path。
如果drive给出X:,dir给出\DIR\SUBDIR\,name给出NAME,和.ext给出.EXT,根据给定的组成部分,可建立一个完整的盘区路径文件名path为:
X:\DIR\CUBDIR\NAME.EXT
int fnsplit(const char *path,char *drive,char *cir,char *name,char *ext);
可把由path给出的盘区路径文件名扩展名分解成为各自的组成部分.返回一整型数.
FILE*fopen (const char *filemane,const char *mode);
打开文件filemane返回相联系的流;出错返回NULL。
mode字符串的可取值有:r,打开用于读;w,打开用于写;a,打开用于在原有内容之后写;r+,打开已存在的文件用于更新(读和写);w+创建新文件用于更新;a+,打开用于在原有内容之后更新,若文件不存在就创建。
unsigned FP_OFF(void far *farptr);
返回远指针farptr的地址偏移量。
int fprintf(FILE *stream,const char *format[,argument,...]);
照原样抄写格式串format的内容到流stream中,每遇到一个%,就按规定的格式,依次输出一个表达式argument的值到流stream中,返回写的字符个数。出错时返回EOF。
FILE *stream;
void main( void )
{
long l;
float fp;
char s[81];
char c;
stream = fopen( "fscanf.txt", "w+" );
if( stream == NULL )
printf( "The file fscanf.out was not opened\n" );
else {fprintf( stream, "%s %ld %f%c", "a-string",65000, 3.14159, 'x' );
/* Set pointer to beginning of file: */
fseek( stream, 0L, SEEK_SET );
/* Read data back from file: */
fscanf( stream, "%s", s );
fscanf( stream, "%ld", &l );
fscanf( stream, "%f",
fscanf( stream, "%c", &c );/* Output data read: */
printf( "%s\n", s );
printf( "%ld\n", l );
printf( "%f\n", fp );
printf( "%c\n", c );
fclose( stream ); }
}
int fputc(int c,FILE *stream);
写一个字符到流中。
成功时返回所写的字符,失败或出错时返回EOF。
int fputchar(int c);
送一个字符到屏幕。
等价于fputc(c,stdout);成功时返回所写的字符,失败或出错时返回EOF。
int fputs(const char *s,FILE *stream);
把s所指的以空字符终结的字符串送入流中,不加换行符'\n',不拷贝串结束符'\0'。
成功时返回最后的字符,出错时返回EOF。
size_t fread(void *ptr,size_t size,size_t n,FILE *stream);
从所给的输入流stream中读取的n项数据,每一项数据长度为size字节,到由ptr所指的块中。
成功时返回所读的数据项数(不是字节数);遇到文件结束或出错时可能返回0。
void free(void *block);
释放先前分配的首地址为block的内存块。
int freemem(unsigned segx);
释放先前由allocmem分配的段地址为segx的内存块。
FILE *freopen(const char *filename,const char *mode,FILE *stream);
用filename所指定的文件代替打开的流stream所指定的文件。返回stream,出错时返回NULL。
double frexp(double x int *exponent);
将x分解成尾数合指数。
将给出的双精度数x分解成为在0.5和1之间尾数m和整形的指数n,使原来的x=m*(2的n次方),将整形指数n存入exponent所指的地址中,返回尾数m。
int fscan(FILE *stream,char *format,address,...);
fscanf扫描输入字段,从流stream读入,每读入一个字段,就依次按照由format所指的格式串中取一个从%开始的格式进行格式化之后存入对应的一个地址address中。返回成功地扫描,转换和存贮输入字段的个数,遇文件结束返回EOF。
FILE *stream;
void main( void )
{
long l;
float fp;
char s[81];
char c;
stream = fopen( "fscanf.txt", "w+" );
if( stream == NULL )
printf( "The file fscanf.out was not opened\n" );
else {fprintf( stream, "%s %ld %f%c", "a-string",65000, 3.14159, 'x' );
/* Set pointer to beginning of file: */
fseek( stream, 0L, SEEK_SET );
/* Read data back from file: */
fscanf( stream, "%s", s );
fscanf( stream, "%ld", &l );
fscanf( stream, "%f",
fscanf( stream, "%c", &c );/* Output data read: */
printf( "%s\n", s );
printf( "%ld\n", l );
printf( "%f\n", fp );
printf( "%c\n", c );
fclose( stream ); }
}
int fseek(FILE *stream,long offset,int whence);
在流上重新定位文件结构的位置。fseek设置与流stream相联系的文件指针到新的位置,新位置与whence给定的文件位置的距离为offset字节。whence的取值必须是0,1或2中的一个,分别代表在stdio.h中定义的三个符号常量:
0是SEEK_SET,是文件开始位置;
1是SEEK_CUR,是当前的指针位置;
2时SEEK_END,是文件末尾。
调用了fseek之后,在更新的文件位置上,下一个操作可以是输入;也可以是输出。成功地移动了指针时,fseek返回0;出错或失败时返回非0值。
例:
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FILE *stream;
void main( void )
{
long l;
float fp;
char s[81];
char c;
stream = fopen( "fscanf.txt", "w+" );
if( stream == NULL )
printf( "The file fscanf.out was not opened\n" );
else {fprintf( stream, "%s %ld %f%c", "a-string",65000, 3.14159, 'x' );
/* Set pointer to beginning of file: */
fseek( stream, 0L, SEEK_SET );
/* Read data back from file: */
fscanf( stream, "%s", s );
fscanf( stream, "%ld", &l );
fscanf( stream, "%f",
fscanf( stream, "%c", &c );/* Output data read: */
printf( "%s\n", s );
printf( "%ld\n", l );
printf( "%f\n", fp );
printf( "%c\n", c );
fclose( stream ); }
}
int fsetpos(FILE *stream,const fpos_t *pos);
fsetpos把与stream相联系的文件指针置于新的位置。这个新的位置是先前对此流调用fgetpos所得的值。fsetpos清除stream所指文件的文件结束标志,并消除对该文件的所有ungetc操作。在调用fsetpos之后,文件的下一操作可以是输入或输出。
调用fsetpos成功时返回0;若失败,返回非0值。
int fstat(int handle,struct stat *statbuf);
把与handle相联系的打开文件或目录的信息存入到statbuf所指的定义在sys\stat.h中的stat结构中。成功时返回0;出错时返回-1。
long int ftell(FILE *stream);
返回流stream中当前文件指针位置。偏移量是文件开始算起的字节数。出错时返回-1L,是长整数的-1值。
void ftime(struct timeb *buf);
把当前时间存入到在sys\timeb.h中定义的timeb结构中。
size_t fwrite(const void *ptr,size_t size,size_t n,FILE *stream);
fwrite从指针ptr开始把n个数据项添加到给定输出流stream,每个数据项的长度为size个字节。
成功是返回确切的数据项数(不是字节数);出错时返回短(short)计数值。可能是0。
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:
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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:
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/* 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:
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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:
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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:
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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:
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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:
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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:
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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:
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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:
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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:
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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; }