CODEWITHSUNDEEP
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Bình Nguyên
Bình Nguyên

Reputation: 2352

Different between % operator of C language and mod of google calculator

I calc -15 mod 18 and here are results:
C: -15 % 18 = -15 (http://codepad.org/DhzkZYHk)
Google: -15 mod 18 = 3 (Type -15 mod 18 into google's search box)

and results of -9 mod 5:
C: -9 % 5 = -4
Google: -9 mod 5 =1

Why these are differents? And how google calculate their mod?

Upvotes: 1

Views: 4432

Answers (2)

Varad
Varad

Reputation: 145

Google's calculator does -15 mod 18 as

-15 = 18*(-1) + 3

giving a remainder of 3, whereas C evaluates it as

-15 = 18*(0) - 15

and hence the expression becomes -15.

In general,

a = (a/b)*b + a%b

holds.

Upvotes: 2

ouah
ouah

Reputation: 145899

Because the % operator in Google is a modulus operator and the % operator in C is a remainder operator.

Modulus and remainder operators differ with respect to negative values. With the modulus operator the sign of the result is the sign of the divisor and with the remainder operator the sign of the result is the sign of the dividend.

Upvotes: 2

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