Integer type and behavior in PHP - Step-by-Step Execution

Concept Flow - Integer type and behavior

Start: Assign integer

↓

Check integer size

↓

Store integer in memory

↓

Use integer in operations

↓

Check for overflow

No Yes↓

Continue

↓

End

This flow shows how PHP handles integers: assign, store, use, check overflow, and convert if needed.

Execution Sample

PHP

<?php
$int = 2147483647;
echo $int;
$int2 = $int + 1;
echo "\n" . $int2;
?>

Assigns max 32-bit integer, prints it, adds 1 causing overflow, then prints the result.

Execution Table

Step	Variable	Value	Operation	Result/Output
1	$int	2147483647	Assign max 32-bit int	2147483647
2	Output	2147483647	Print $int	2147483647
3	$int2	2147483648	Add 1 to $int	2147483648 (converted to float on 32-bit)
4	Output	2147483648	Print $int2	2147483648

💡 Execution ends after printing both values; integer overflow handled by conversion to float on 32-bit systems.

Variable Tracker

Variable	Start	After Step 1	After Step 3	Final
$int	undefined	2147483647	2147483647	2147483647
$int2	undefined	undefined	2147483648 (float on 32-bit)	2147483648 (float on 32-bit)

Key Moments - 2 Insights

Why does adding 1 to 2147483647 not cause an error but changes the type?

PHP converts integers that overflow 32-bit limits into floats automatically, as shown in step 3 of the execution_table.

Is the output of $int2 still an integer after adding 1?

No, on 32-bit systems it becomes a float due to overflow, as seen in the variable_tracker after step 3.

Visual Quiz - 3 Questions

Look at the execution_table at step 3, what is the type of $int2 after adding 1 on a 32-bit system?

A Float

B Integer

C String

D Boolean

💡 Hint

Check the 'Result/Output' column at step 3 in execution_table.

At which step is the first output printed?

A Step 1

B Step 2

C Step 3

D Step 4

💡 Hint

Look for the 'Print $int' operation in execution_table.

If PHP was running on a 64-bit system, what would likely happen to $int2 after adding 1?

A It causes an error

B It becomes a float

C It stays an integer

D It becomes a string

💡 Hint

On 64-bit systems, integers can hold larger values without overflow.

Concept Snapshot

PHP Integer Type and Behavior:
- Integers are whole numbers stored in memory.
- Max size depends on system (32-bit or 64-bit).
- Overflow on 32-bit converts integer to float.
- Operations on integers follow normal math rules.
- Use echo to print integer values.

Full Transcript

This visual execution trace shows how PHP handles integers. First, an integer variable is assigned the maximum 32-bit integer value 2147483647. This value is printed. Then, 1 is added to this integer, which causes an overflow on 32-bit systems. PHP automatically converts the result to a float type to hold the larger number 2147483648. This new value is printed. The variable tracker shows the integer variable remains unchanged, while the new variable holds a float after overflow. Key moments clarify why the type changes and how PHP manages integer overflow. The quiz tests understanding of type changes and output steps. The snapshot summarizes integer behavior in PHP.