CODEWITHSUNDEEP
loopsfor-loopprocessing
Ahum
Ahum

Reputation: 19

Write a program that adds together all the numbers between 0 and 100. Print the result

I want to write a program that adds all the numbers between 0 and 100 but my code does not add everything correctly. How do I add the next number to the number and then print the sum?

This is the code I have:

         for(int i = 0; i <= 100; i++){
           i+=i;
           println(i);
         }

The result of this shows 0, 2, 6, 14... and I need the sum of all the numbers 1 through 100.

Upvotes: 0

Views: 908

Answers (1)

nucandrei
nucandrei

Reputation: 951

The reason you are getting this odd result is that you add those numbers to i instead of having a dedicated collector.

int collector = 0;
for (int i = 0; i <= 100; i++) {
       collector += i;
       println(collector);
}

If you only want to print the sum once, move the println(collector) expression outside the loop.

There is also a mathematical formula to directly compute the sum of the first n numbers

Sum(1, n) = n * (n+1) / 2

In Processing:

int Sum(int n){
  return n * (n + 1) / 2;
}

The formula works because the numbers 1 to N can be rearranged and added like this:

 (1 + N) + (2 + N-1) + (3 + N-2) + . . . . + (N + N/2+1) = total

for N = 100:

 (1 + 100) + (2 + 99) + (3 + 98) + . . . . + (50 + 51) = 5050
   101     +   101    +   101    + . . . . +    101    = 5050

Upvotes: 3

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