C 库函数大全按字母排序

[ 永远的UNIX > C语言库函数(F类字母) ] 首页 > 编程技术 > C/C++ > 正文 C语言库函数(F类字母) 本文出自:http://www.asfocus.com 作者: (2001-07-27 15:00:00) 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 <stdio.h> #include <math.h> int main(void) { float number = -1234.0; printf("number: %f absolute value: %f\n", 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: #include <stdio.h> #include <alloc.h> #include <string.h> #include <dos.h> 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 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: %Fs\n", fptr); /* free the memory */ farfree(fptr); return 0; } 函数名: farcoreleft 功 能: 返回远堆中未作用存储区大小 用 法: long farcoreleft(void); 程序例: #include <stdio.h> #include <alloc.h> int main(void) { printf("The difference between the\ highest allocated block in the\ far\n"); printf("heap and the top of the far heap\ is: %lu bytes\n", 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 <stdio.h> #include <alloc.h> #include <string.h> #include <dos.h> 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 can't 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: %Fs\n", 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 *farmalloc(unsigned long size); 程序例: #include <stdio.h> #include <alloc.h> #include <string.h> #include <dos.h> 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 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: %Fs\n", fptr); /* free the memory */ farfree(fptr); return 0; } 函数名: farrealloc 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 <stdio.h> #include <alloc.h> int main(void) { char far *fptr; fptr = farmalloc(10); printf("First address: %Fp\n", fptr); fptr = farrealloc(fptr,20); printf("New address : %Fp\n", fptr); farfree(fptr); return 0; } 函数名: fclose 功 能: 关闭一个流 用 法: int fclose(FILE *stream); 程序例: #include <string.h> #include <stdio.h> int main(void) { FILE *fp; char buf[11] = "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: #include <stdio.h> 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 streams 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 <stdlib.h> #include <stdio.h> #include <conio.h> int main(void) { char *string; double value; int dec, sign; int ndig = 10; clrscr(); value = 9.876; string = ecvt(value, ndig, &dec, &sign); printf("string = %s dec = %d \ sign = %d\n", string, dec, sign); value = -123.45; ndig= 15; string = ecvt(value,ndig,&dec,&sign); printf("string = %s dec = %d sign = %d\n", string, dec, sign); value = 0.6789e5; /* scientific notation */ ndig = 5; string = ecvt(value,ndig,&dec,&sign); printf("string = %s dec = %d\ sign = %d\n", 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 <sys\stat.h> #include <stdio.h> #include <fcntl.h> #include <io.h> i