cc [ flag ... ] file ... -lm [ library ... ] #include <math.h>double ceil(double x);
Upon successful completion, ceil() returns the smallest integral value not less than x, expressed as a type double.
If x is NaN, NaN is returned.
If x is ±Inf or ±0, x is returned.
No errors will occur.
The integral value returned by ceil() as a double may not be expressible as an int or long int. The return value should be tested before assigning it to an integer type to avoid the undefined results of an integer overflow.
See attributes(5) for descriptions of the following attributes:
|ATTRIBUTE TYPE||ATTRIBUTE VALUE|