How can I detect integer overflow on 32 bits int?

Math.addExact throws exception on overflow Since Java 8 there is a set of methods in the Math class: toIntExact(long) addExact(int,int) subtractExact(int,int) multiplyExact(int,int) …and versions for long as well. Each of these methods throws ArithmeticException if overflow happens. Otherwise they return the proper result if it fits within the range. Example of addition: int x = … Read more

Often big numbers become negative

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: -9,223,372,036,854,775,808 to 9,223,372,036,854,775,807 In the image 0000, 0001 etc, shows the binary representation of the numbers. EDIT: In project euler you often have to … Read more

Allowing signed integer overflows in C/C++

Signed overflow is undefined in C, and that’s for real. One solution follows: signed_result = (unsigned int)one_argument + (unsigned int)other_argument; The above solution involves implementation-defined behavior in the final conversion from unsigned to int but do not invoke undefined behavior. With most compilation platforms’ implementation-defined choices, the result is exactly the two’s complement result that … Read more

C++ integer overflow

Signed integer overflow is undefined behaviour, while unsigned integer overflow is well-defined; the value wraps around. In other words, the value is modulo divided by 2bits, where bits is the number of bits in the data type. Since you’ve a 32-bit int 4294967295 + 1 = 4294967296 % 232 = 0 it results in 0 … Read more

Wrap around explanation for signed and unsigned variables in C?

Signed integer variables do not have wrap-around behavior in C language. Signed integer overflow during arithmetic computations produces undefined behavior. Note BTW that GCC compiler you mentioned is known for implementing strict overflow semantics in optimizations, meaning that it takes advantage of the freedom provided by such undefined behavior situations: GCC compiler assumes that signed … Read more