CODEWITHSUNDEEP
loopsfor-loopjuliadecrement
Bilesh Ganguly
Bilesh Ganguly

Reputation: 4131

How to implement a decrementing for loop in Julia?

I know that in python I can do something as follows.

for i in range(10, 0, -1):
    print(i)

Which will output:

10
9
8
7
6
5
4
3
2
1

I'm very much new to julia and I know I can create normal loops as follows.

for i=1:10
    println(i)
end

Intuitively, I tried something like as follows (since I thought it behaved similar to python's range([start], stop[, step]) function).

for i=10:1:-1
    println(i)
end

Although it didn't fail, it didn't print anything either. What am I doing wrong?

Is there an intuitive way to loop backwards in julia?

Upvotes: 8

Views: 2399

Answers (1)

Bogumił Kamiński
Bogumił Kamiński

Reputation: 69819

Try this:

julia> for i=10:-1:1
           println(i)
       end
10
9
8
7
6
5
4
3
2
1

or this

julia> for i=reverse(1:10)
           println(i)
       end
10
9
8
7
6
5
4
3
2
1

As @phipsgabler noted you can also use:

julia> range(10, 1, step=-1)
10:-1:1

to get the same result again (note though that you have to use 1 as a second index).

From my practice range is usually more useful with with length keyword argument:

julia> range(10, 1, length=10)
10.0:-1.0:1.0

(notice that in this case you get a vector of Float64 not Int)

Upvotes: 12

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