Return values in Go - Step-by-Step Execution

Concept Flow - Return values

Start function call

↓

Execute function body

↓

Return value(s)

↓

Receive returned value(s)

↓

Continue program

This flow shows how a function runs, sends back value(s), and the program uses them.

Execution Sample

Go

package main
import "fmt"
func add(a, b int) int {
    return a + b
}
func main() {
    fmt.Println(add(3, 4))
}

This code defines a function that adds two numbers and returns the sum, then prints it.

Execution Table

Step	Action	Variables	Return Value	Output
1	Call add(3, 4)	a=3, b=4
2	Calculate a + b	a=3, b=4	7
3	Return 7 to caller	a=3, b=4	7
4	Print returned value			7
5	Program ends

💡 Function returns value 7, printed by main, then program ends

Variable Tracker

Variable	Start	After Step 1	After Step 2	Final
a	-	3	3	3
b	-	4	4	4
return value	-		7	7

Key Moments - 2 Insights

Why do we see the return value only after the function finishes?

Because the function runs all its code first (see Step 2), then sends back the value (Step 3). The program waits for this before printing.

What happens if the function has no return statement?

The function returns nothing (void). In Go, if the function signature says it returns a value, it must have a return statement (not shown here).

Visual Quiz - 3 Questions

Look at the execution table, what is the return value at Step 3?

A 7

B 3

C 4

D 0

💡 Hint

Check the 'Return Value' column at Step 3 in the execution table.

At which step does the program print the returned value?

A Step 2

B Step 3

C Step 4

D Step 5

💡 Hint

Look at the 'Output' column in the execution table to find when printing happens.

If we change add(3, 4) to add(5, 6), what will be the return value at Step 3?

A 7

B 11

C 9

D 0

💡 Hint

Return value is sum of inputs a and b, see variable values in variable_tracker.

Concept Snapshot

func functionName(params) returnType {
    // code
    return value
}

- Function runs code then returns value.
- Caller receives and can use returned value.
- Return ends function execution.

Full Transcript

This example shows how a Go function returns a value. The function add takes two numbers, adds them, and returns the sum. The program calls add(3, 4), the function runs and returns 7. Then main prints 7. The execution table traces each step: calling the function, calculating sum, returning value, printing output, and ending. Variables a and b hold inputs, return value holds the sum. Beginners often wonder why return happens after all code runs; it does because return sends the final result back to the caller. If the function had no return, it would return nothing. Changing inputs changes the return value accordingly. This is the basic flow of return values in Go functions.