VBA宏运行时错误'9'：下标超出范围-数组

Question

I have been experiencing a error when I try to generate a population for a GA. I used a 2d array to help generate a population. First the user will enter the population size and then the chromosome length, into a userform.

My variables:

Dim Generation As Integer
Dim Chromolength As Integer
Dim varchromolength As Integer
Dim Poparr() As Integer

Then i fetch the values from the userform:

PopSize = PopulationSize.value
aVariables = AOV.value          'assign userform value entered to this variable
varchromolength = Chromolengthentered.value    'assign userform value entered to this   variable
Chromolength = varchromolength * aVariables   'Chromosome length equals the length of     each varaible chromosome combined

Then the coding where the error ocurs:

For i = 1 To PopSize           
   For j = 1 To Chromolength       
    If Rnd < 0.5 Then           
        Poparr(i, j) = 0   'assign o to gene
    Else
        Poparr(i, j) = 1   'assign 1 to gene     
    End If
   Next j
Next i

I apologize, I am fairly new to VBA. Any help with this error will be appreciated.

Answer 1

Based on your code, you never assign the dimensions of the array. To do so, insert this line before your for loop, after setting the values of PopSize and ChromoLength .

Redim Poparr(1 to PopSize, 1 to ChromoLength)

Unnecessary details: You could just run Redim Poparr(PopSize, ChromoLength) but that would result in arrays that were 0 to Popsize etc... unless you add Option Base 1 to the top of your module. The default base for arrays is 0. I feel that it is better to explicitly indicate the lowerbound and upperbound of your array because the default can be 0 or 1 depending on the context.