Goto statement overview in C - Step-by-Step Execution

Concept Flow - Goto statement overview

Start

↓

Execute statements

↓

Check for goto

↓

Jump to label

↓

End

The program runs statements in order, but when it hits a goto, it jumps to a labeled spot and continues from there.

Execution Sample

C

int main() {
  int x = 0;
  if (x == 0) goto skip;
  x = 1;
  skip:
  return x;
}

This code uses goto to jump over the assignment x = 1 if x is 0, then returns x.

Execution Table

Step	Line	Action	Variable x	Notes
1	int x = 0;	Initialize x to 0	0	x set to 0
2	if (x == 0) goto skip;	Check if x is 0	0	Condition true, jump to label skip
3	skip:	Label reached	0	Jumped here, skip x=1
4	return x;	Return x value	0	Function returns 0
5	-	End of program	0	Program ends

💡 Program ends after returning x, which is 0 because assignment x=1 was skipped

Variable Tracker

Variable	Start	After Step 1	After Step 2	After Step 3	Final
x	undefined	0	0	0	0

Key Moments - 2 Insights

Why does the assignment x = 1 not happen?

Because at step 2 in the execution_table, the condition x == 0 is true, so the goto jumps directly to the label 'skip', skipping the assignment line.

What happens if the goto condition is false?

If the condition was false, the program would continue normally without jumping, executing the assignment x = 1 before reaching the label.

Visual Quiz - 3 Questions

Look at the execution_table, what is the value of x after step 3?

A undefined

B 0

C 1

D 2

💡 Hint

Check the 'Variable x' column at step 3 in the execution_table.

At which step does the program jump to the label 'skip'?

A Step 3

B Step 1

C Step 2

D Step 4

💡 Hint

Look at the 'Action' column in the execution_table for the goto decision.

If the condition in step 2 was false, what would be the value of x at the end?

A 1

B 0

C undefined

D 2

💡 Hint

If no jump occurs, the assignment x=1 would run before return.

Concept Snapshot

Goto statement overview in C:
- Syntax: goto label;
- Execution jumps to the label anywhere in the function
- Labels end with a colon (label:)
- Use carefully to avoid confusing flow
- Skips normal sequential execution
- Useful for simple jumps or error handling

Full Transcript

This example shows how the goto statement works in C. The program starts by setting x to 0. Then it checks if x equals 0. Since it does, the program jumps to the label 'skip', skipping the assignment x = 1. Finally, it returns x, which is still 0. The execution table shows each step and variable values. The variable tracker confirms x stays 0 throughout. Beginners often wonder why the assignment is skipped; it's because of the jump at step 2. If the condition was false, the program would run the assignment normally. The goto statement lets you jump to a labeled spot in the code, changing the normal flow.