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Integer overflow

Hello to everyone.

When I have to calculate the average of two integer numbers, first i have to add them. Sometimes an overflow occurs. One technique maybe to compare the result to one of the numbers, if result is lower, an overflow is recognized.

Is this good style or better use Assembler?

Parents

0 Georget Stephane over 19 years ago

How about something like that:

signed int Number1;
signed int Number2;

// Possibly CPU intensive, but quite accurate
// even with odd numbers
signed int AverageMethod1 = (signed int) ((long signed int)Number1 + (long signed int)Number2) / 2);
// Faster but could be a couple of bits off
// with odd numbers
signed int AverageMethod2 = Number1 / 2 +  Number2 / 2;

$0.02

Reply

0 Georget Stephane over 19 years ago

How about something like that:

signed int Number1;
signed int Number2;

// Possibly CPU intensive, but quite accurate
// even with odd numbers
signed int AverageMethod1 = (signed int) ((long signed int)Number1 + (long signed int)Number2) / 2);
// Faster but could be a couple of bits off
// with odd numbers
signed int AverageMethod2 = Number1 / 2 +  Number2 / 2;

$0.02

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