How does the modulus operator work?

Question

Let's say that I need to format the output of an array to display a fixed number of elements per line. How do I go about doing that using modulus operation?

Using C++, the code below works for displaying 6 elements per line but I have no idea how and why it works?

for ( count = 0 ; count < size ; count++) {     cout << somearray[count];     if( count % 6 == 5) cout << endl; } 

What if I want to display 5 elements per line? How do i find the exact expression needed?

Answer 1

in C++ expression a % b returns remainder of division of a by b (if they are positive. For negative numbers sign of result is implementation defined). For example:

5 % 2 = 1 13 % 5 = 3 

With this knowledge we can try to understand your code. Condition count % 6 == 5 means that newline will be written when remainder of division count by 6 is five. How often does that happen? Exactly 6 lines apart (excercise : write numbers 1..30 and underline the ones that satisfy this condition), starting at 6-th line (count = 5).

To get desired behaviour from your code, you should change condition to count % 5 == 4, what will give you newline every 5 lines, starting at 5-th line (count = 4).

Answer 2

Basically modulus Operator gives you remainder simple Example in maths what's left over/remainder of 11 divided by 3? answer is 2

for same thing C++ has modulus operator ('%')

Basic code for explanation

#include <iostream> using namespace std;   int main() {     int num = 11;     cout << "remainder is " << (num % 3) << endl;      return 0; } 

Which will display

remainder is 2