get integer from a string in php

Question

I have a string that represents a temperature. This string is dynamically parsed from a website and it can contain also negative values. For example, it can be -1 C, or 2 C and so on.

I want to get only the integer value. Here is my code:

$temp_number = preg_replace("/-?[0-9]+/", '', $value); 
echo "Temperature : ". $value . "Number : ".$temp_number."<br/>";

I thought that the temp_number should be the extracted number BUT it is the C for example. Here is my output.

Temperature : 0℃   Number : ℃

What should I use? I do not want to replace the string, I want to extract it.

Answer 1

Try this instead:

$temp_number = preg_replace("/[^-0-9]+/", '', $value); 
echo "Temperature : ". $value . "Number : ".$temp_number."<br/>";

The regex of [^-0-9]+ basically states that it should strip away anything that is not a - or a number.

Answer 2

intval seems like an obvious solution here, much simpler than a regex. (Your example makes it appear as if the string is always just a number followed by C, and temperatures aren't usually recorded in decimals, so: intval.)

Proof: http://ideone.com/DjI3jG

Answer 3

1.Like Jessica said above intval is much simpler

$value = '0℃';
$number = intval($value);
echo $number; // which is 0 integer

2.Also, you can use filter_var

$value = '0℃';
$number = filter_var($value,FILTER_SANITIZE_NUMBER_INT);

Answer 4

Can you try this, Use /[^0-9]/ in your regex

$number = preg_replace("/[^0-9]/", '', $value);

echo "Temperature : ". $value . "Number : ".$number ."<br/>";

Answer 5

try this use "/[^0-9]/" as regex

$value="100";
$temp_number = (int)preg_replace("/[^0-9]/", '', $value); 
echo "Temperature : ". $value . "Number : ".$temp_number."<br/>";

output:

Temperature : 100Number : 100