为什么$ variable = 0759给出61？ [重复]

Question

This question already has an answer here:

• What does a leading zero do for a php int? 4 answers

I don't know how to google this one out so I an asking it here. Why does it happen that when I declare a variable $something = 0759 that it turns into 61. I know the answer must be very simple so please forgive my sillyness.

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Answer 1

It is an Integer literal, you declare a octal number with a leading zero.

$something = 0759; // octal

The octal numeral system is a base-8 number system. You can only use Numbers between 0-7 (other numbers are discarded).

$a = 0759; 
$b = 075;
var_dump($a==$b);
// bool(true)

http://www.php.net/manual/en/language.types.integer.php

You could skip the zeros with ltrim.

 $a = ltrim("0759", 0); 
 echo $a; // 759
 // and reformat as suggested with str_pad or printf
 echo str_pad($a, 4, "0", STR_PAD_LEFT);