Else–if ladder in C - Step-by-Step Execution

Concept Flow - Else–if ladder

Start

↓

Check condition1

|Yes↓

Execute block1

↓

End

No↓

Check condition2

|Yes↓

Execute block2

↓

End

No↓

Check condition3

|Yes↓

Execute block3

↓

End

No↓

Execute else block

↓

End

The program checks conditions one by one from top to bottom. When a condition is true, it runs that block and skips the rest. If none are true, it runs the else block.

Execution Sample

C

int x = 15;
if (x < 10) {
    printf("Less than 10\n");
} else if (x < 20) {
    printf("Between 10 and 19\n");
} else {
    printf("20 or more\n");
}

This code checks the value of x and prints which range it falls into using an else-if ladder.

Execution Table

Step	Condition Checked	Condition Result	Action Taken	Output
1	x < 10	False	Skip block
2	x < 20	True	Execute block	Between 10 and 19
3	Else block	Skipped	Skip block
4	End	-	Exit ladder

💡 Condition x < 20 is True, so that block runs and ladder ends.

Variable Tracker

Variable	Start	After Step 1	After Step 2	Final
x	15	15	15	15

Key Moments - 2 Insights

Why does the program skip the else block after a true condition?

Once a true condition is found and its block runs (see Step 2 in execution_table), the else-if ladder ends immediately, so the else block is skipped.

What happens if all conditions are false?

If all conditions are false (like Step 1 and Step 2 false), the else block runs as a fallback (not shown in this example but explained in the flow).

Visual Quiz - 3 Questions

Look at the execution_table, what is the result of the first condition check?

A False

B True

C Skipped

D Error

💡 Hint

Check Step 1 row under 'Condition Result' column in execution_table.

At which step does the program print output?

A Step 1

B Step 3

C Step 2

D Step 4

💡 Hint

Look for the 'Output' column in execution_table where text appears.

If x was 25, which block would run?

A First if block

B Else block

C Second else-if block

D No block runs

💡 Hint

Refer to the concept_flow and think what happens when all conditions are false.

Concept Snapshot

Else–if ladder syntax:
if (condition1) {
  // block1
} else if (condition2) {
  // block2
} else {
  // else block
}

Checks conditions top-down, runs first true block, else runs if none true.

Full Transcript

This example shows how an else-if ladder works in C. The program checks each condition in order. If a condition is true, it runs that block and skips the rest. If none are true, it runs the else block. Here, x is 15. First condition x < 10 is false, so it skips. Second condition x < 20 is true, so it prints 'Between 10 and 19' and ends. The else block is skipped. Variables stay the same throughout. This helps decide between multiple choices step-by-step.