php将任意进制的数转换成10进制，例如8进制转换成10进制，16进制转换成10进制
<?php # Show the steps involved in converting a number # from any base (like octal or hex) to base 10 # See below for examples, instructions and copyright function show_convert_to_base_10 ($number, $base) { // If the number contains a decimal component if (strstr ($number, '.')) { // Get the integer and decimal components list ($integer, $decimal) = explode ('.', $number); } else { // The number is an integer $integer = $number; } print "<b>Convert the base $base number $number to a base 10 number:</b><blockquote>"; print "Convert the integer component ($integer) of the number:<blockquote>"; // Compute the value of the integer component // Loop through the integer digit by digit // Reverse the number for easier handling $integer = strrev ($integer); $length = strlen ($integer); for ($pos = 0; $pos < $length; ++$pos) { /* PHP lets you treat strings and numbers like arrays Specify an offset and get the character at that position */ $digit = $integer[$pos]; // Handle character values for digits // (for bases greater than 10) if (eregi ('[a-z]', $digit)) { $digit_value = (ord (strtolower ($digit)) - ord ('a')) + 10; $digit = "$digit ($digit_value)"; } else { $digit_value = $digit; } // Multiply the current digit by the radix // raised to the power of the current position $result = $digit_value * pow ($base, $pos); print "Multiply the value of the digit at position $pos by the value of the radix ($base) raised to the power of the position ($pos):<br/>"; print "$digit * $base<sup>$pos</sup> = $result <br/><br/>"; $sums[] = $result; } print '</blockquote>'; if (isset ($decimal)) { print "Convert the decimal component (0.$decimal) of the number:<blockquote>"; // Pad the number with a leading 0 so that we can // start at position 1 $decimal = '0'.$decimal; $length = strlen ($decimal); for ($pos = 1; $pos < $length; ++$pos) { $digit = $decimal[$pos]; // Handle character values for digits // (for bases greater than 10) if (eregi ('[a-z]', $digit)) { $digit_value = (ord (strtolower ($digit)) - ord ('a')) + 10; $digit = "$digit ($digit_value)"; } else { $digit_value = $digit; } // Multiply the current digit by the radix // raised to the power of the current position $result = $digit_value * pow (1/$base, $pos); print "Multiply the value of the digit at position $pos by the value of the 1/radix ($base) raised to the power of the position ($pos):<br/>"; print "$digit * 1/$base<sup>$pos</sup> = $result<br/><br/>"; $sums[] = $result; } print '</blockquote>'; } $sums = implode (' + ', $sums); eval ("\$base_10_value = $sums;"); print "</blockquote>The value of the base $base number $number in base 10 is $base_10_value. <br/>"; print "This number is derived from the sum of the values of the previous operations ($sums). <br/> <br/>"; }