If-else statements in Blockchain / Solidity - Step-by-Step Execution

Concept Flow - If-else statements

Start

↓

Evaluate Condition

↓

Execute If Block

↓

End If-Else

↓

Execute Else Block

↓

End If-Else

The program checks a condition. If true, it runs the 'if' part; if false, it runs the 'else' part.

Execution Sample

Blockchain / Solidity

if (balance >= amount) {
  send(amount);
} else {
  revert("Insufficient funds");
}

Checks if balance is enough to send amount; sends if yes, else stops with error.

Execution Table

Step	Condition (balance >= amount)	Result	Branch Taken	Action
1	balance=100, amount=50	True	If	send(50) called
2	balance=30, amount=50	False	Else	revert("Insufficient funds") called

💡 Execution stops after either sending amount or reverting due to insufficient funds.

Variable Tracker

Variable	Start	After Step 1	After Step 2
balance	100	100	30
amount	50	50	50

Key Moments - 2 Insights

Why does the code run the else block when balance is less than amount?

Because the condition balance >= amount is false (see execution_table row 2), so the else branch runs.

What happens if the condition is true?

The if block runs and the send function is called (see execution_table row 1). The else block is skipped.

Visual Quiz - 3 Questions

Look at the execution table, what action happens when balance is 100 and amount is 50?

A Nothing happens

B revert("Insufficient funds") is called

C send(50) is called

D Both send and revert are called

💡 Hint

Check execution_table row 1 where condition is true and if branch runs.

At which step does the condition become false?

A Step 2

B Step 1

C Never

D Both steps

💡 Hint

Look at execution_table row 2 where condition is false.

If amount was 20 instead of 50 at step 2, what would happen?

A Else branch runs

B If branch runs

C Code reverts anyway

D No action taken

💡 Hint

Compare balance and amount in variable_tracker and condition in execution_table.

Concept Snapshot

If-else statements check a condition.
If true, run the 'if' block.
If false, run the 'else' block.
Used to control program flow based on conditions.
Syntax: if (condition) { ... } else { ... }

Full Transcript

This visual trace shows how if-else statements work in blockchain programming. The program checks if balance is enough to send an amount. If yes, it calls send(amount). If no, it calls revert with an error message. The execution table shows two steps: one where the condition is true and send is called, and one where the condition is false and revert is called. Variables balance and amount are tracked to see their values at each step. Key moments clarify why the else block runs when the condition is false and what happens when it is true. The quiz tests understanding of which branch runs based on the condition. The snapshot summarizes the if-else concept simply.