![]() ![]() Have fun! Encrypt a few messages to try out the code. with an equivalent positive operand that has the same wrap-around effect Implement modulo by replacing the negative operand There are multiple ways to implement modulo in JavaScript. Since we now understand that JavaScript doesn’t have a true modulo operator, we can easily implement our modulo operation as a function. Let's suppose we need to implement a (scientific) calculation in JavaScript by using modulo arithmetic. This difference in behavior between languages may introduce subtle errors in your calculation, especially if you are trying to port an algorithm from one language to another! A problem understood is a problem half solved In Python, for instance, the % operator calculates the true modulo in the same way as Google: However, not all programming languages / frameworks have the same implementation for %. Google calculates the true modulo, while these computer languages calculate a signed reminder. this shouldn’t be actually a surprise if we look at the definition of % operator in JavaScript (… or even C# or many other languages). Let’s now try to use a negative value as the first operand: Next type the same expressions in the Google search bar. Type there, one by one, the calculations from the left column. In Chrome, open the console (press F12 and select the Console tab). Let’s do some tests by comparing the results returned by JavaScript with the ones returned by Google. Therefore the operand should be correctly referred to as the signed remainder operator.Īt first sight the signed remainder operator functions similarly to the modulo operator. In C# and JavaScript % operator is used actually to calculate the remainder (with sign) left over when one operand is divided by the second operand. Wow! This is a subtle but very dangerous mistake. Plenty of documentation refer to the % sign as modulo operator. This article focuses on the modulo operator.Īsk any C# or JavaScript programmer what is the modulo operator in their language and there is a big chance that they’ll gone answer: % (e.g. Sometimes the situations is complicated by falsely advertised or understood framework functions or operators. Try to ignore the limitations or framework specs and soon you’ll find out that you have an impedance mismatch between your mathematical formula and the code you try to write. Successful implementation of a scientific calculation or algorithm is possible not only by understanding the features that a particular language or framework offers but also understanding the limitations.Ĭomputers are precise scientific instruments but they do they work by manipulating entities in discrete spaces (you have a limited number of pixels on the screen, there is a limited numbers of bits that are behind each number, etc.)
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