C语言F.docx

1、C语言F返回C语言函数大全函数名: fabs功 能: 返回浮点数的绝对值用 法: double fabs(double x);程序例: #include #include int main(void) float number = -1234.0; printf(number: %f absolute value: %fn, number, fabs(number); return 0;函数名: farcalloc功 能: 从远堆栈中申请空间用 法: void far *farcalloc(unsigned long units, unsigned ling unitsz);程序例:#incl

2、ude #include #include #include int main(void) char far *fptr; char *str = Hello; /* allocate memory for the far pointer */ fptr = farcalloc(10, sizeof(char); /* copy Hello into allocated memory */ /* Note: movedata is used because you might be in a small data model, in which case a normal string cop

3、y routine can not be used since it assumes the pointer size is near. */ movedata(FP_SEG(str), FP_OFF(str), FP_SEG(fptr), FP_OFF(fptr), strlen(str); /* display string (note the F modifier) */ printf(Far string is: %Fsn, fptr); /* free the memory */ farfree(fptr); return 0;函数名: farcoreleft功 能: 返回远堆中未作

4、用存储区大小用 法: long farcoreleft(void);程序例:#include #include int main(void) printf(The difference between the highest allocated block in the farn); printf(heap and the top of the far heap is: %lu bytesn, farcoreleft(); return 0;函数名: farfree功 能: 从远堆中释放一块用 法: void farfree(void);程序例:#include #include #inclu

5、de #include int main(void) char far *fptr; char *str = Hello; /* allocate memory for the far pointer */ fptr = farcalloc(10, sizeof(char); /* copy Hello into allocated memory */ /* Note: movedata is used because you might be in a small data model, in which case a normal string copy routine cant be u

6、sed since it assumes the pointer size is near. */ movedata(FP_SEG(str), FP_OFF(str), FP_SEG(fptr), FP_OFF(fptr), strlen(str); /* display string (note the F modifier) */ printf(Far string is: %Fsn, fptr); /* free the memory */ farfree(fptr); return 0;函数名: farmalloc功 能: 从远堆中分配存储块用 法: void far *farmall

7、oc(unsigned long size);程序例:#include #include #include #include int main(void) char far *fptr; char *str = Hello; /* allocate memory for the far pointer */ fptr = farmalloc(10); /* copy Hello into allocated memory */ /* Note: movedata is used because we might be in a small data model, in which case a

8、 normal string copy routine can not be used since it assumes the pointer size is near. */ movedata(FP_SEG(str), FP_OFF(str), FP_SEG(fptr), FP_OFF(fptr), strlen(str); /* display string (note the F modifier) */ printf(Far string is: %Fsn, fptr); /* free the memory */ farfree(fptr); return 0;函数名: farre

9、alloc功 能: 调整远堆中的分配块用 法: void far *farrealloc(void far *block, unsigned long newsize);程序例:#include #include int main(void) char far *fptr; fptr = farmalloc(10); printf(First address: %Fpn, fptr); fptr = farrealloc(fptr,20); printf(New address : %Fpn, fptr); farfree(fptr); return 0;函数名: fclose功 能: 关闭一

10、个流用 法: int fclose(FILE *stream);程序例:#include #include int main(void) FILE *fp; char buf11 = 0123456789; /* create a file containing 10 bytes */ fp = fopen(DUMMY.FIL, w); fwrite(&buf, strlen(buf), 1, fp); /* close the file */ fclose(fp); return 0;函数名: fcloseall功 能: 关闭打开流用 法: int fcloseall(void);程序例:#

11、include int main(void) int streams_closed; /* open two streams */ fopen(DUMMY.ONE, w); fopen(DUMMY.TWO, w); /* close the open streams */ streams_closed = fcloseall(); if (streams_closed = EOF) /* issue an error message */ perror(Error); else /* print result of fcloseall() function */ printf(%d strea

12、ms were closed.n, streams_closed); return 0;函数名: fcvt功 能: 把一个浮点数转换为字符串用 法: char *fcvt(double value, int ndigit, int *decpt, int *sign);程序例:#include #include #include int main(void) char *string; double value; int dec, sign; int ndig = 10; clrscr(); value = 9.876; string = ecvt(value, ndig, &dec, &si

13、gn); printf(string = %s dec = %d sign = %dn, string, dec, sign); value = -123.45; ndig= 15; string = ecvt(value,ndig,&dec,&sign); printf(string = %s dec = %d sign = %dn, string, dec, sign); value = 0.6789e5; /* scientific notation */ ndig = 5; string = ecvt(value,ndig,&dec,&sign); printf(string = %s

14、 dec = %d sign = %dn, string, dec, sign); return 0;函数名: fdopen功 能: 把流与一个文件句柄相接用 法: FILE *fdopen(int handle, char *type);程序例:#include #include #include #include int main(void) int handle; FILE *stream; /* open a file */ handle = open(DUMMY.FIL, O_CREAT, S_IREAD | S_IWRITE); /* now turn the handle int

15、o a stream */ stream = fdopen(handle, w); if (stream = NULL) printf(fdopen failedn); else fprintf(stream, Hello worldn); fclose(stream); return 0;函数名: feof功 能: 检测流上的文件结束符用 法: int feof(FILE *stream);程序例:#include int main(void) FILE *stream; /* open a file for reading */ stream = fopen(DUMMY.FIL, r);

16、/* read a character from the file */ fgetc(stream); /* check for EOF */ if (feof(stream) printf(We have reached end-of-filen); /* close the file */ fclose(stream); return 0;函数名: ferror功 能: 检测流上的错误用 法: int ferror(FILE *stream);程序例:#include int main(void) FILE *stream; /* open a file for writing */ st

17、ream = fopen(DUMMY.FIL, w); /* force an error condition by attempting to read */ (void) getc(stream); if (ferror(stream) /* test for an error on the stream */ /* display an error message */ printf(Error reading from DUMMY.FILn); /* reset the error and EOF indicators */ clearerr(stream); fclose(strea

18、m); return 0;函数名: fflush功 能: 清除一个流用 法: int fflush(FILE *stream);程序例:#include #include #include #include void flush(FILE *stream);int main(void) FILE *stream; char msg = This is a test; /* create a file */ stream = fopen(DUMMY.FIL, w); /* write some data to the file */ fwrite(msg, strlen(msg), 1, str

19、eam); clrscr(); printf(Press any key to flush DUMMY.FIL:); getch(); /* flush the data to DUMMY.FIL without closing it */ flush(stream); printf(nFile was flushed, Press any key to quit:); getch(); return 0;void flush(FILE *stream) int duphandle; /* flush the streams internal buffer */ fflush(stream);

20、 /* make a duplicate file handle */ duphandle = dup(fileno(stream); /* close the duplicate handle to flush the DOS buffer */ close(duphandle);函数名: fgetc功 能: 从流中读取字符用 法: int fgetc(FILE *stream);程序例:#include #include #include int main(void) FILE *stream; char string = This is a test; char ch; /* open

21、a file for update */ stream = fopen(DUMMY.FIL, w+); /* write a string into the file */ fwrite(string, strlen(string), 1, stream); /* seek to the beginning of the file */ fseek(stream, 0, SEEK_SET); do /* read a char from the file */ ch = fgetc(stream); /* display the character */ putch(ch); while (c

22、h != EOF); fclose(stream); return 0;函数名: fgetchar功 能: 从流中读取字符用 法: int fgetchar(void);程序例:#include int main(void) char ch; /* prompt the user for input */ printf(Enter a character followed by : ); /* read the character from stdin */ ch = fgetchar(); /* display what was read */ printf(The character re

23、ad is: %cn, ch); return 0;函数名: fgetpos功 能: 取得当前文件的句柄用 法: int fgetpos(FILE *stream);程序例:#include #include int main(void) FILE *stream; char string = This is a test; fpos_t filepos; /* open a file for update */ stream = fopen(DUMMY.FIL, w+); /* write a string into the file */ fwrite(string, strlen(str

24、ing), 1, stream); /* report the file pointer position */ fgetpos(stream, &filepos); printf(The file pointer is at byte %ldn, filepos); fclose(stream); return 0;函数名: fgets功 能: 从流中读取一字符串用 法: char *fgets(char *string, int n, FILE *stream);程序例:#include #include int main(void) FILE *stream; char string =

25、 This is a test; char msg20; /* open a file for update */ stream = fopen(DUMMY.FIL, w+); /* write a string into the file */ fwrite(string, strlen(string), 1, stream); /* seek to the start of the file */ fseek(stream, 0, SEEK_SET); /* read a string from the file */ fgets(msg, strlen(string)+1, stream); /* display the string */ printf(%s, msg); fclose(stream); return 0;函数名: filelength功 能: 取文件长度字节数用 法: long filelength(int handle);程序例:#include #incl