Use of unassigned variable (string)

Question

I have a piece of code that iterates over XML attributes:

string groupName;
do
{
    switch (/* ... */)
    {
        case "NAME":
            groupName = thisNavigator.Value;
            break;
        case "HINT":
            // use groupName

But this way I get the error of using an unassigned variable. If I assign something to groupName then I cannot change it because that's how the strings work in C#. Any workarounds ?

Answer 1

You are right that strings are immutable in .NET, but your assumption that a string variable can't be changed is wrong.

This is valid and fine:

string groupName = null;
groupName = "aName";
groupName = "a different Name";

Your code will not have an error if you do the following:

string groupName = string.Empty; // or null, if empty is meaningful
do
{
    switch (/* ... */)
    {
        case "NAME":
            groupName = thisNavigator.Value;
            break;
        case "HINT":
            // use groupName

Answer 2

Does the default of your switch assign a value to groupName? If not, then that will be causing the error.

switch
{
  case "NAME":
    groupName = thisNavigator.Value;
    break;
  //...
  default:
    groupName = "something";
    break;
}

Answer 3

string groupName = string.Empty;

Just assign an empty string and your should be okej.

Answer 4

The compiler is unaware of the context of your switch statement (e.g. there's no guarantee that the switch will always match a case).

So it's possible for groupName to remain unassigned even after the switch.

You can instantiate groupName with String.Empty or use default: in your switch statement.

Answer 5

Set groupName in each case and use default key in switch statement or assign groupName to null before switch.