Passing value types to methods in C Sharp (C#) - Step-by-Step Execution

Concept Flow - Passing value types to methods

Start with value variable

↓

Call method with value

↓

Method receives a copy

↓

Modify copy inside method

↓

Method ends, copy discarded

↓

Original variable unchanged

↓

End

When you pass a value type to a method, the method gets a copy. Changes inside the method do not affect the original variable.

Execution Sample

C Sharp (C#)

int x = 5;
ModifyValue(x);
Console.WriteLine(x);

void ModifyValue(int num) {
  num = 10;
}

This code shows passing an integer (value type) to a method that changes the copy, but the original stays the same.

Execution Table

Step	Variable	Value Before	Action	Value After	Output
1	x	5	Initialize x with 5	5
2	Call ModifyValue(x)	x=5	Pass copy of x to num	num=5
3	num	5	Inside method: num = 10	10
4	Method ends	num=10	num copy discarded	-
5	x	5	Print x after method call	5	5

💡 Method ends, original x remains 5 because only a copy was changed

Variable Tracker

Variable	Start	After Call	Inside Method	After Method	Final
x	5	5	-	5	5
num	-	-	5	10	-

Key Moments - 2 Insights

Why does changing 'num' inside the method not change 'x'?

Because 'num' is a copy of 'x' (see execution_table step 3). Changes to 'num' do not affect the original 'x'.

Is the original variable 'x' modified after the method call?

No, 'x' remains 5 after the method call (see execution_table step 5) because only a copy was changed.

Visual Quiz - 3 Questions

Look at the execution table, what is the value of 'num' inside the method after assignment?

A 10

B 5

C 0

D Undefined

💡 Hint

Check execution_table row 3 where 'num' is assigned 10 inside the method.

At which step does the original variable 'x' remain unchanged?

A Step 3

B Step 5

C Step 2

D Step 4

💡 Hint

Look at execution_table step 5 where 'x' is printed and still has value 5.

If the method modified 'num' by adding 5 instead of setting 10, what would be the final value of 'x'?

A 10

B 0

C 5

D Method error

💡 Hint

Remember from variable_tracker that 'x' is unchanged after method call because only a copy is modified.

Concept Snapshot

Passing value types to methods:
- The method gets a copy of the value.
- Changes inside the method affect only the copy.
- Original variable remains unchanged after method returns.
- Use 'ref' or 'out' to pass by reference if modification is needed.

Full Transcript

In C#, when you pass a value type like int to a method, the method receives a copy of the value. This means any changes made inside the method affect only the copy, not the original variable. For example, if you pass an integer x with value 5 to a method that sets its parameter to 10, the original x remains 5 after the method call. This is because the method works on a separate copy. To modify the original variable, you would need to pass it by reference using keywords like 'ref' or 'out'.