Initialising Before Passing

Example: out Parameter

void GetValues(out int a)
{
    a = 10;  // Must assign inside the method
}
 
int number;          // Not initialized
GetValues(out number);
Console.WriteLine(number); // 10

• Notice number was never given a value before GetValues was called.

• Inside GetValues, the value must be assigned (a = 10).

• After the call, number now holds 10.

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Contrast with ref

void Increment(ref int x)
{
    x += 5;
}
 
int number;           // Not initialized
Increment(ref number); // ❌ Error: must initialize before passing

• ref requires that the variable already has a value before calling the method.

• The method can then read and modify it.

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Key Idea

• out → method is responsible for giving the variable a value; the caller doesn’t have to set it first.

• ref → caller must set the variable first; method can then read and modify it.