PHP Program to Strict Integer Input with Explanation
PHP
Easy
PHP Error Handling
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1 min read
83 words
This problem helps you practice core PHP fundamentals in a practical way. It builds intuition around token, invalid, strict. Let’s break it down step by step so you can implement it confidently.
Problem Statement
If the token is not a valid integer (optional sign, digits only), print INVALID.
Input Format
One token s.
Output Format
Integer or INVALID.
Constraints
|s|
Code Solution
This explanation is written for learning purposes and to help beginners understand the concept clearly.
<?php
$inputText=trim(stream_get_contents(STDIN));
if($inputText==='') exit;
if(preg_match('/^[+-]?[0-9]+$/',$inputText)) echo intval($inputText);
else echo 'INVALID';
?>
Common Mistakes
- Misreading input/output format.
- Not handling constraints and edge cases.
- Off-by-one errors in loops.
- Forgetting to reset variables between test cases (if any).
Solution Guide
Problem
If the token is not a valid integer (optional sign, digits only), print INVALID.
Input / Output
Output
Integer or INVALID.
Details
Common Mistakes
- Misreading input/output format.
- Not handling constraints and edge cases.
- Off-by-one errors in loops.
- Forgetting to reset variables between test cases (if any).
Official Solution
<?php
$inputText=trim(stream_get_contents(STDIN));
if($inputText==='') exit;
if(preg_match('/^[+-]?[0-9]+$/',$inputText)) echo intval($inputText);
else echo 'INVALID';
?>
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