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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

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!

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