#include <stdio.h>
#include <stdlib.h>

int main(){
    int a[] = {0,0,1,0,0,1,0,2};
    const char *table = "0123456789";
    size_t size = sizeof(a)/sizeof(*a);
    char *b = malloc(size+1);
    int i;
    for(i=0;i<size;++i)
        b[i]=table[a[i]];
    b[i]='\0';
    printf("%s\n", b);
    free(b);
    return 0;
}

Maybe you are trying to do:

string combinedString = string.Join( ",", myList.ToArray() );

You can replace , with whatever character you want to split the elements in the list by.

Also, as mentioned in the comments you could also do:

string combinedString = string.Join( ",", myList);

Reference:

Join<T>(String, IEnumerable<T>)

Concatenates the members of a constructed IEnumerable collection of type String, using the specified separator between each member.

You can use String.Join. If you have a List<string> then you can call ToArray first:

List<string> names = new List<string>() { "John", "Anna", "Monica" };
var result = String.Join(", ", names.ToArray());

In .NET 4 you don't need the ToArray anymore, since there is an overload of String.Join that takes an IEnumerable<string>.

In newer versions of .NET different String.Join overloads use different approaches to produce the result. And this might affect the performance of your code.

For example, those that accept IEnumerable use StringBuilder under the hood. And the one that accepts an array uses a heavily optimized implementation with arrays and pointers.

Results:

John, Anna, Monica