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What's the difference between "mod" and "remainder"?

My friend said that there are differences between "mod" and "remainder".

If so, what are those differences in C and C++? Does '%' mean either "mod" or "rem" in C?

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In C and C++ and many languages, `%` is the remainder NOT the modulus operator.

For example in the operation `-21 / 4` the integer part is `-5` and the decimal part is `-.25`. The remainder is the fractional part times the divisor, so our remainder is `-1`. JavaScript uses the remainder operator and confirms this





 console.log(-21 % 4 == -1);



The modulus operator is like you had a "clock". Imagine a circle with the values 0, 1, 2, and 3 at the 12 o'clock, 3 o'clock, 6 o'clock, and 9 o'clock positions respectively. Stepping quotient times around the clock clock-wise lands us on the result of our modulus operation, or, in our example with a negative quotient, counter-clockwise, yielding 3.

**Note:** Modulus is always the same sign as the divisor and remainder the same sign as the quotient. Adding the divisor and the remainder when at least one is negative yields the modulus.

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2

Did you mean that sign of the remainder is always the same sign as the dividend? The quotient of 7 / -3 = -2, but 7 rem -3 = 1.

dx_over_dt
– dx_over_dt

2020年11月09日 16:52:16 +00:00
Commented Nov 9, 2020 at 16:52
"remainder the same sign as the quotient" --> No, not in C. 7/-3 has the quotient -2 and the 7%-3 has the remainder of 1.

chux
– chux

2022年12月12日 08:43:06 +00:00
Commented Dec 12, 2022 at 8:43

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What's the difference between "mod" and "remainder"?

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