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# integer overflow ## integers have a limited amount of space The 4 usual sizes for integers are 8 bits, 16 bits, 32 bits, and 64 bits ## the biggest 8-bit unsigned integer is 255 ... so what happens if you do 255 + 1? ## going above/below the limits is called overflow the result wraps around to the other side * 255 + 1 = 0 * 255 + 3 = 2 * 200 * 2 = 144 * 0 - 2 = 254 ## maximum numbers for different sizes bits: unsigned signed 8: 127 255 16: 32767 65535 32: 2 billion ~4 billion 64: ~9 quintillion ~18 quintillion ## overflows often don't throw errors computer (thinking): "255 + 1? that number is 8 bits, so the answer is 0! that's what you wanted right?" This can cause VERY tricky bugs ## some languages where integer overflow happens * Java/Kotlin * C/C++ * Rust * Swift * C# * SQL * R * Go * Dart * Python (only in numpy) Some throw errors on overflow, some don't, for some it depends on various factors. Look up how it works in your language!