Convert float to int in Julia Lang

Question

Is there a way to convert a floating number to int in Julia? I'm trying to convert a floating point number to a fixed precision number with the decimal part represented as 8bit integer. In order to do this, I need to truncate just the decimal part of the number and I figured the best way to do this would be to subtract the converted integer of x from floating point x:

  x = 1.23455
y = x - Int(x)
println(y)

y = 0.23455

Solution 1

I think you are looking for floor:

julia> x = 1.23455
1.23455

julia> floor(x)
1.0

julia> y = x - floor(x)
0.23455000000000004

Solution 2

It is possible that you are looking for trunc. It depends on what you mean by the decimal part. This is the difference between trunc and floor:

julia> trunc(Int, 1.2)
1

julia> trunc(Int, -1.2)
-1

julia> floor(Int, 1.2)
1

julia> floor(Int, -1.2)
-2

Solution 3

Combining the previous answers:

julia> int(x) = floor(Int, x)
int (generic function with 1 method)

julia> int(3.14)
3

julia> int(3.94)
3

Solution 4

To answer the general question in the title (convert Float to Int), we can do:

round(Int, 1.3)
# 1
round(Int, 1.7)
# 2

Solution 5

according to floor docs you can do that way

julia> x = 45.5
45.5

julia> typeof(x)
Float64

julia> x = floor(Int8,x)
45

julia> typeof(x)
Int8

View more solutions

Comments

[jjjjjj]

As of v0.6, note that the output of floor is not an Int64 type, but rather a Float64 as per the example: test = ceil(0.2); typeof(test)

[karatedog]

trunc returns Float now, not Integer.

[Fengyang Wang]

@karatedog trunc(x::Float64) has always returned Float. But if you provide Int as the first argument, as in trunc(Int, 1.2), you will get an integer.

[Yousef Saber]

floor(Int,x) is more accurately according to docs

[Olov]

It is recommended to use the alias Int instead of explicitly stating the size of the integer, see docs.julialang.org/en/v1/manual/types/#Type-Aliases-1

[Muppet]

I'm sorry, but not why do round(Int64, 1.3) instead? It's much more concise? What's the purpose of adding an explicit conversion?

[Hansang]

This should be the best answer