Return values and void methods in C Sharp (C#) - Step-by-Step Execution

Concept Flow - Return values and void methods

Method Called

↓

Execute Method Body

↓

Is method void?

Yes→No return value, end method

No↓

Return value to caller

↓

Continue execution after method call

When a method is called, it runs its code. If it returns a value, that value goes back to the caller. If it's void, it just finishes without returning anything.

Execution Sample

C Sharp (C#)

int Add(int a, int b) {
    return a + b;
}

void PrintSum(int x, int y) {
    Console.WriteLine(x + y);
}

Defines a method that returns the sum of two numbers and a void method that prints the sum.

Execution Table

Step	Action	Method	Parameters	Return Value	Output
1	Call Add(3, 4)	Add	a=3, b=4	7
2	Return 7 to caller	Add		7
3	Call PrintSum(5, 6)	PrintSum	x=5, y=6	void
4	Print 11 to console	PrintSum		void	11
5	End of PrintSum method	PrintSum		void

💡 Methods finish after returning a value or completing void execution.

Variable Tracker

Variable	Start	After Step 1	After Step 3	Final
a	-	3	-	-
b	-	4	-	-
x	-	-	5	-
y	-	-	6	-
Return Value	-	7	void	-

Key Moments - 2 Insights

Why does the Add method return a value but PrintSum does not?

Add has a return statement that sends a value back (see step 2 in execution_table). PrintSum is declared void, so it does not return anything and just finishes after printing (steps 3-5).

What happens if you try to use the return value of a void method?

Void methods do not produce a value, so trying to use their return value will cause an error. The execution_table shows PrintSum returns 'void' and no value is passed back.

Visual Quiz - 3 Questions

Look at the execution_table, what is the return value of Add(3,4) at step 2?

A void

B 7

C 11

D 3

💡 Hint

Check the 'Return Value' column at step 2 in the execution_table.

At which step does PrintSum output to the console?

A Step 1

B Step 3

C Step 4

D Step 5

💡 Hint

Look at the 'Output' column for PrintSum in the execution_table.

If Add method did not have a return statement, what would happen?

A It would cause a compile error

B It would return 0 by default

C It would behave like a void method

D It would return null

💡 Hint

In C#, non-void methods must return a value; see the concept_snapshot for rules.

Concept Snapshot

Method with return value:
- Declared with a type (e.g., int)
- Uses 'return' to send value back
- Caller can use returned value

Void method:
- Declared with 'void'
- Does not return value
- Performs actions like printing

All methods end after return or finishing code.

Full Transcript

When you call a method, the program runs the code inside it. If the method is declared to return a value, it must use the 'return' keyword to send that value back to where it was called. For example, the Add method takes two numbers and returns their sum. The caller can then use this returned number. On the other hand, a void method does not return any value. It just runs its code and finishes. For example, PrintSum adds two numbers and prints the result but does not send anything back. Trying to get a return value from a void method causes an error. Also, if a method is declared to return a value but does not have a return statement, the program will not compile. This is because C# requires all non-void methods to return a value. Understanding these rules helps you write methods that either give back results or just perform actions.