Freemarker code to split consecutive numbers

Question

I need to split consecutive numbers.

Case 1) 34123

Output: 34 123

Case 2) 123434123

Output: 1234 34 123

Answer 1

[#function splitConsecutiveNumbers input]
    [#assign output = ""]
    [#list 0..<input?length as i]
        [#if !i?is_last]
            [#if (input[i]?number+1) != input[i+1]?number]
                [#assign output += input[i] + " "]
            [#else]
                [#assign output += input[i]]
            [/#if]
        [#else]
            [#assign output += input[i]]
        [/#if]
    [/#list]
    [#return output]
[/#function]

${splitConsecutiveNumbers("34123")}
${splitConsecutiveNumbers("123434123")}