PHP - price validation script

programming
1

I have searched for a script like this one but I can’t find it. I’m trying to make a price validation script that will allow strings like…
[LIST]
[]42
[]42.5
[*]42.50
[/LIST]

But will disallow and prompt me for strings like…
[LIST]
[]abcd
[]ac42
[]42ab
[]4512
[]85&88)
[]42.50.30.20
[]42,50
[/LIST]

The script will only allow numbers and, if entered, at least one period and thats it. Can someone please help me or point me to the right direction.

Here is a script I have to make sure its ONLY numbers:


			// ----- if the field should contain ONLY NUMBERS -----
			if(eregi('number',$fieldnames[$i])&&$column!='')
			{
				// get fieldname in CAPS
				$numberfield = str_replace('number', '', $fieldnames[$i]);
				$numberfield = strtoupper($numberfield);

				// strip everything that its not a number
				$column = preg_replace('|[^0-9]|', '', $column);

				if(!eregi('[0-9]', $column))
				{
					$errors .= '<li>Please enter digits as '.$numberfield.'.</li>';
				}
			}