What are some uses of the modulus operator? I know that it calculates the remainder in division so really I am asking what uses does the remainder have?
So far I have used it to check if a number was even and alternate colors on a table.
codymanix
2010-10-20 16:16:24
True...I use it a lot more for conditional checking against queued pairs.
Andrew Sledge
2010-10-20 16:46:25
+2
A:
- Unit conversion, e.g.
13425 mis13425 / 1000 km and 13425 % 1000 m=13 km and 425 m - random number trimming, if you're using C/C++'s rand(), a common idiom is
rand() % (HIGH - LOW) + LOWto generate a random number between HIGH and LOW - modular arithmetic: angles are limited to 360 degrees or 2*pi, you can normalize their range using modulus operator
- even/odd check: if "n % 2" is true then n is even otherwise it's odd
Lie Ryan
2010-10-20 16:15:04
+6
A:
for(int i=0;i<10;i++)
{
if((i % 2) == 0 )
{
// I'm in an even row
}else{
// I'm in an odd row
}
}
The most basic use
Note: lang used Java
org.life.java
2010-10-20 16:15:22
you seem to have that backwards. even numbers mod to 0 which is false. Also, might it be simpler to just unroll it and have two steps in the loop, for both even and odd?
Tesserex
2010-10-20 16:28:45
i mean instead of using the mod operator, your loop body could contain: code for even row; i++; code for odd row. It's really about readability, which will depend on the exact scenario.
Tesserex
2010-10-20 16:32:50
@Tesserex :) Here I am demonstrating the most basic and simpler use of `%` operator , I didn't say this is the most efficient code
org.life.java
2010-10-20 16:34:22
A:
A programming 101 exapmle would be to modulate row colors for data:
for(int i = 0; i < 100; i++)
{
write-color i % 2;
}
Determine if a number is evan or odd:
return number % 2;
Nate Bross
2010-10-20 16:16:08
+4
A:
Getting an indication of progress in a long running loop by printing a message once every so many iterations.
List<Thing> bigList = readBigList();
for (int i = 0; i < bigList.size(); i++) {
processThing(bigList.get(i));
if (i % 10000 == 0) {
LOG.info("Processed " + i + " out of " + bigList.size() + " items");
}
}
oksayt
2010-10-20 16:16:54
@Lie Yeah, see Chapter 39 of A.K Dewdney's "The Turing Omnibus" not sure why, but the subtitle to the chapter is "Chinese Arithmetic" and he writes about the Chinese Remainder Theorem.
Peter Turner
2010-10-20 16:29:25
A:
The modulus operator is the single-most important operator in Clock Arithmetic.
Ani
2010-10-20 16:24:45
This is where I use it most often, it makes it easy to setup a repeating sequence of numbers by just adding 1 to the counter each clock tick. The last time I did this it was to drive the animation loop in a sprite.
asawyer
2010-10-20 17:16:48
+1
A:
It's generally used to check if one number is evenly divisible by another.
if(number % 2 == 0){
// the number is even
} else {
// the number is odd
}
or
if(number % 3 == 0){
// the number is evenly divisible by three
} else {
// the number is not evenly divisible by three
}
If the result of a mod operation is 0, the dividend (number) is evenly divisible by the divisor.
You can take advantage of this to do things like "piano-keys" style alternate-row shading on table data, or printing new column headings every X number of rows, or what have you.
Brad
2010-10-20 16:49:09