integer-overflow

I was just wondering how disastrous integer overflow really is. Take the following example program: #include <iostream> int main() { int a = 46341; int b = a * a; std::cout << "hello world\n"; } Since a * a overflows on 32 bit platforms, and integer overflow triggers undefined behavior, do I have any guarantees at all that hello world will actually appear on my screen? I removed the "signed" part from my question based on the following standard quotes: (§5/5 C++03, §5/4 C++11) If during the evaluation of an expression, the result is not mathematically defined or not in the range of

There's (1): // assume x,y are non-negative if(x > max - y) error; And (2): // assume x,y are non-negative int sum = x + y; if(sum < x || sum < y) error; Whichs is preferred or is there a better way. Integer overflow is the canonical example of "undefined behaviour" in C (noting that operations on unsigned integers never overflow, they are defined to wrap-around instead). This means that once you've executed x + y , if it overflowed, you're already hosed. It's too late to do any checking - your program could have crashed already. Think of it like checking for division by zero - if you wait

If I type the following into the immediate window I get Runtime error '6': Overflow. MsgBox 24 * 60 * 60 Why is this? This also fails: Dim giveTime As Long giveTime = 24 * 60 * 60 Why is this? giveTime is declared as a Long type, so 24 × 60 × 60 = 86400 should comfortably fit. This is a really odd VBA quirk. I'm amazed I've never bumped into this. Dim x As Long x = 24 * 60 * 60 ' Overflow x = 32767 + 1 ' Overflow. x = 32768 + 1 ' Works fine! So it looks like the * and + operators return an Integer in the first two examples. Sure enough, in the help file for the * operator (similar for the +

Since I started using eclipse for project euler, I noticed that big numbers sometime become a seemingly random negative numbers. I suppose this has something to do with passing the boudry of the type. I'll be glad if you could explain to me how these negative numbers are generated and what is the logic behind it. Also, how can I avoid them (preferable not with BigInteger class). Danke!=) Goatcat This image shows what you're looking for. In your case it's obviously larger numbers, but the principle stays the same. Examples of limits in java are: int: −2,147,483,648 to 2,147,483,647. long: -9

The following block of codes gives the output as 0. public class HelloWorld{ public static void main(String []args){ int product = 1; for (int i = 10; i <= 99; i++) { product *= i; } System.out.println(product); } } Please can somebody explain why this happens? Here is what the program does at each step: 1 * 10 = 10 10 * 11 = 110 110 * 12 = 1320 1320 * 13 = 17160 17160 * 14 = 240240 240240 * 15 = 3603600 3603600 * 16 = 57657600 57657600 * 17 = 980179200 980179200 * 18 = 463356416 463356416 * 19 = 213837312 213837312 * 20 = -18221056 -18221056 * 21 = -382642176 -382642176 * 22 = 171806720

During Java Arithmetic operation , JVM do not throw Underflow or Overflow Exception. So many time we come across unexpected results and wondering what went wrong. While in case of .NET technology we have Overflow and Undeflow exception. So my question is that , why Java was design not to throw this exception during arithmetic operation This was likely a combination of factors: The big languages prior to Java used unchecked arithmetic. Well-known algorithms prone to numerical overflow tended to account for the potential overflow already without relying on checked arithmetic. Checked arithmetic

I'm working on a programming language, and today I got the point where I could compile the factorial function(recursive), however due to the maximum size of an integer the largest I can get is factorial(12). What are some techniques for handling integers of an arbitrary maximum size. The language currently works by translating code to C++. If you need larger than 32-bits you could consider using 64-bit integers (long long), or use or write an arbitrary precision math library, e.g. GNU MP . If you want to roll your own arbitrary precision library, see Knuth's Seminumerical Algorithms, volume 2