c# - Changing one element of an array changes others

Question

I have the following piece of code:

Chromosome[] pop = new Chromosome[popSize];      
int[] initialGenes = new int[i];  
for (int m = 0; m < i; m++)  
     initialGenes[m] = -1;  
     for (int j = 0; j < popSize; j++)  
     {                
        pop[j] = new Chromosome(graph, initialGenes);  
     }  

Chromosome is my class and has a property

public int[] Genes { get; set; }

As you can see I initialize an array of Chromosome objects. The problem is when I try to change the value of pop[i].Genes[k] (e.g. pop[1].Genes[2] = 123) all Genes[k] of pop are changed (i.e.

pop[0].Genes[2] == 123
pop[2].Genes[2] == 123 

etc.)

Could anyone explain what the problem is?
Thanks.

Answer 1

Change your constructor of Chromosome to make a copy of the array that is passed in.
I assume, your constructor looks like this:

public Chromosome(int[] initialGenes)
{
    Genes = initialGenes;
}

But it should look like this:

public Chromosome(int[] initialGenes)
{
    Genes = new int[initialGenes.Length];
    Array.Copy(initialGenes, Genes, Genes.Length);
}