The TI-99/4A computer has a more angular capital O and a more rounded digit 0, whereas others made the choice the other way around. Some fonts designed for use with computers made one of the capital-O–digit-0 pair more rounded and the other more angular (closer to a rectangle). This could be confused with the Greek letter Theta on a badly focused display, but in practice there was no confusion because theta was not (then) a displayable character and very little used anyway.Īn alternative, the slashed zero (looking similar to the letter O except for the slash), was primarily used in hand-written coding sheets before transcription to punched cards or tape, and is also used in old-style ASCII graphic sets descended from the default typewheel on the Teletype Model 33 ASR.
One variation used a short vertical bar instead of the dot. Its appearance has continued with Taligent's command line typeface Andalé Mono. The digit 0 with a dot in the centre seems to have originated as an option on IBM 3270 displays. So 1 << 2, is equal to 4 as you take 1 and shift by 2 bits. In math, this looks like: x (2y) or x pow (2, y) The << operator is a bit shifter.
x << y - means shift bits of x to the left (to larger value) y times. The distinction came into prominence on modern character displays. 1 << 0 is 1 shifted to the left by 0 positions, which is just 1. Typewriters originally made no distinction in shape between O and 0 some models did not even have a separate key for the digit 0. Traditionally, many print typefaces made the capital letter O more rounded than the narrower, elliptical digit 0.