Java low level: Converting between integers and text (part 2)
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Java low level: Converting between integers and text (part 2)
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Parsing an integer is relatively simple depending on how many checks you make. This loop does almost no validation. The input can multiple '-' signs and the number can overflow. As soon as it reaches a character is does not accept to stops. It is left to the caller to check if this character was a valid separartor.
long num = 0;
boolean negative = false;
while (true) {
byte b = buffer.get();
// if (b >= '0' && b <= '9')
if ((b - ('0' + Integer.MIN_VALUE)) <= 9 + Integer.MIN_VALUE)
num = num * 10 + b - '0';
else if (b == '-')
negative = true;
else
break;
}
return negative ? -num : num;
Note: The expression
(b >= '0' && b <= '9') has been re-written taking advantage of an underflow to turn this into one comparison.
To follow...
Converting floating point numbers to text
From http://vanillajava.blogspot.com/2011/07/java-low-level-converting-between_14.html
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