golang - ceil function like php?

The line

d := float64(length / pagesize)

transforms to float the result of the division. Since the division itself is integer division, it results in 4, so d = 4.0 and math.Ceil(d) is 4.

Replace the line with

d := float64(length) / float64(pagesize)

and you'll have d=4.3 and int(math.Ceil(d))=5.

Convert length and pagesize to floats before the division:

d := float64(length) / float64(pagesize)

http://play.golang.org/p/FKWeIj7of5

Avoiding floating point operations (for performance and clarity):

x, y := length, pagesize
q := (x + y - 1) / y;

for x >= 0 and y > 0.

Or to avoid overflow of x+y:

q := 1 + (x - 1) / y

It's the same as the C++ version: Fast ceiling of an integer division in C / C++

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