another problem confuse me

kuigg · 11-29-2008, 01:41 PM

hi,thank the guys solved my preceding puzzle.
now I want to know that why the result of " intval(042); " is 34 but not 42,who can tell me ?

thanks ,

Salathe · 11-29-2008, 02:52 PM

The number 042 is an octal number (base 8) rather than a 'normal' decimal number (base 10). It's the octal 42 which can be explained below:

Octal

Code:

32 16  8  1
-  -   4  2

To work out the decimal value, multiply the header line by the digit line and sum those values. 8*4 + 1*2 which gives 34.

Compare this to decimal numbers

Code:

1000 100 10  1
-    -   4   2

Multiplying the values together again: 10*4 + 1*2 which gives 42.

You can also use hexadecimal (base 16) by preceding the number with 0x. For example, all of the following have an integer value of 123.

PHP Code:


			
$num = 123;  // decimal

$num = 0x7B; // hexadecimal

$num = 0173; // octal

More information can be found on the integers PHP manual page.

kuigg · 11-29-2008, 03:56 PM

Quote:

Originally Posted by Salathe

The number 042 is an octal number (base 8) rather than a 'normal' decimal number (base 10). It's the octal 42 which can be explained below:

Octal

Code:

32 16  8  1
-  -   4  2

To work out the decimal value, multiply the header line by the digit line and sum those values. 8*4 + 1*2 which gives 34.

Compare this to decimal numbers

Code:

1000 100 10  1
-    -   4   2

Multiplying the values together again: 10*4 + 1*2 which gives 42.

You can also use hexadecimal (base 16) by preceding the number with 0x. For example, all of the following have an integer value of 123.

PHP Code:


			
$num = 123;  // decimal

$num = 0x7B; // hexadecimal

$num = 0173; // octal

More information can be found on the integers PHP manual page.

thank you very much.