NAME ceil -- round to smallest integral value not less than x
SYNOPSIS
#include <math.h>
double ceil(double x);
long double ceill(long double x);
float ceilf(float x);
DESCRIPTION
The ceil() functions return the smallest integral value greater than or equal to x.SPECIAL VALUES ceil(+-0) returns +-0. ceil(+-infinity) returns +-infinity.
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NAME abs -- integer absolute value function
LIBRARY Standard C Library (libc, -lc)
SYNOPSIS
#include <stdlib.h>
int abs(int i);
DESCRIPTION The abs() function computes the absolute value of the integer i. RETURNVALUES The abs() function returns the absolute value.
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NAME floor -- round to largest integral value not greater than x
SYNOPSIS
#include <math.h>
double floor(double x);
long double floorl(long double x);
float floorf(float x);
DESCRIPTION
The floor() functions return the largest integral value less than or equal to x.SPECIAL VALUES floor(+-0) returns +-0. floor(+-infinity) returns +-infinity.
原文链接:http://developer.apple.com/library/ios/#documentation/System/Conceptual/ManPages_iPhoneOS/man3/floor.3.html#//apple_ref/doc/man/3/floor
