Multiple return values in Go - Step-by-Step Execution

Concept Flow - Multiple return values

Function called

↓

Execute function body

↓

Prepare multiple return values

↓

Return values to caller

↓

Caller receives multiple values

↓

Use returned values

The function runs, creates multiple values, returns them together, and the caller receives and uses them.

Execution Sample

Go

func divide(a, b int) (int, int) {
    quotient := a / b
    remainder := a % b
    return quotient, remainder
}

q, r := divide(10, 3)

This code divides 10 by 3, returning both quotient and remainder.

Execution Table

Step	Action	Variables	Return Values	Caller Variables
1	Call divide(10, 3)	a=10, b=3	-	-
2	Calculate quotient = 10 / 3	quotient=3	-	-
3	Calculate remainder = 10 % 3	remainder=1	-	-
4	Return quotient and remainder	-	3, 1	-
5	Assign returned values to q, r	-	-	q=3, r=1

💡 Function returns two values and caller stores them in q and r.

Variable Tracker

Variable	Start	After Step 2	After Step 3	After Step 5
a	10	10	10	10
b	3	3	3	3
quotient	-	3	3	-
remainder	-	-	1	-
q	-	-	-	3
r	-	-	-	1

Key Moments - 2 Insights

Why can a function return two values at once?

In Go, functions can return multiple values as a tuple. The execution_table row 4 shows the function returning both quotient and remainder together.

How does the caller receive multiple return values?

The caller assigns the returned values to multiple variables separated by commas, as shown in execution_table row 5 where q and r get the values.

Visual Quiz - 3 Questions

Look at the execution table, what is the value of 'quotient' after step 2?

A 10

B 3

C 1

D 0

💡 Hint

Check the 'Variables' column at step 2 in the execution_table.

At which step does the function return the two values?

A Step 4

B Step 2

C Step 3

D Step 5

💡 Hint

Look for the 'Return Values' column in the execution_table.

If we changed the call to q := divide(10, 3), what would happen?

A q gets a tuple of quotient and remainder

B q gets the quotient, remainder is ignored

C Compilation error because multiple values returned but only one variable to receive

D Function returns only one value automatically

💡 Hint

Go requires the number of variables on the left to match the number of returned values, see variable assignment in execution_table row 5.

Concept Snapshot

func name(params) (type1, type2) {
  // code
  return val1, val2
}

caller1, caller2 := name(args)

- Functions can return multiple values.
- Caller must receive all returned values.
- Useful for returning results and errors together.

Full Transcript

This example shows how a Go function can return multiple values. The function divide takes two integers and returns two integers: the quotient and remainder of division. When called with 10 and 3, it calculates quotient as 3 and remainder as 1. Then it returns both values together. The caller receives these two values and stores them in variables q and r. This way, Go functions can return multiple results at once, which is helpful for many tasks like returning a result and an error. The execution table traces each step: calling the function, calculating values, returning them, and assigning them to caller variables.