Kareem Adams

Greenhorn

Posts: 6

posted 4 years ago

Hi there,

I'm just learning Java and playing around this simple code (it sums up the total of numbers in a range)

It prints sum of 1 to 10. But I don't quite understand the logic in the sum().

If, sum = sum + i;

How does it arrive at the calculation?

sum was initially 0 and i = x = 1 from the above

Then it should read:

initially: sum = sum + 1

x = 1

level 1: 0 = 0 + 1 - initial state, so sum gets to be 1

x = 2

1 = 1 + 2 (1 increments to become 2), so sum gets to be 3 and so on.

This is the logic I'm trying to understand.

Can someone please shed more light on this for me or give it a better explanation.

Thank you.

I'm just learning Java and playing around this simple code (it sums up the total of numbers in a range)

It prints sum of 1 to 10. But I don't quite understand the logic in the sum().

If, sum = sum + i;

How does it arrive at the calculation?

sum was initially 0 and i = x = 1 from the above

Then it should read:

initially: sum = sum + 1

x = 1

level 1: 0 = 0 + 1 - initial state, so sum gets to be 1

x = 2

1 = 1 + 2 (1 increments to become 2), so sum gets to be 3 and so on.

This is the logic I'm trying to understand.

Can someone please shed more light on this for me or give it a better explanation.

Thank you.

posted 4 years ago

I'm not quite sure what it is you're having problems with because, apart from the fact that it's

If need be, just continue the process until i == 10 and work out what

Winston

- 1

Kareem Adams wrote:...

x = 2

1 = 1 + 2 (1 increments to become 2), so sum gets to be 3 and so on.

This is the logic I'm trying to understand.

Can someone please shed more light on this for me or give it a better explanation.

I'm not quite sure what it is you're having problems with because, apart from the fact that it's

`i`that gets incremented, not

`x`, your description seems to be right on the mark.

If need be, just continue the process until i == 10 and work out what

`sum`should contain.

Winston

"Leadership is nature's way of removing morons from the productive flow" - Dogbert

Articles by Winston can be found here

Joanne Neal

Rancher

Posts: 3742

16

Kareem Adams

Greenhorn

Posts: 6

posted 4 years ago

Thanks to you guys, here's what I did.

Doing it manually makes me understand maybe a little (technically).

But the part I really want to get right is in simple English.

How does that part work?

Because what it does is : 1+2+3+4+5+6+7+8+9+10

If I get this right, I'll be able to right something similar with better understanding without looking at any book.

The code I sent earlier was from a book I'm using to study.

And thanks to Matthew for formatting my code earlier.

I appreciate y'all effort.

Doing it manually makes me understand maybe a little (technically).

But the part I really want to get right is in simple English.

How does that part work?

Because what it does is : 1+2+3+4+5+6+7+8+9+10

If I get this right, I'll be able to right something similar with better understanding without looking at any book.

The code I sent earlier was from a book I'm using to study.

And thanks to Matthew for formatting my code earlier.

I appreciate y'all effort.

posted 4 years ago

It works because ints in Java are modifiable, so the statement says:

take the value of

Everything on the right-hand side of the '=' sign is based on the

In some languages (eg, C/C++) these are called 'lvalue's and 'rvalue's ('l' and 'r' being short for 'left' and 'right').

HIH

Winston

- 1

Kareem Adams wrote:But the part I really want to get right is in simple English.

How does that part work?

It works because ints in Java are modifiable, so the statement says:

take the value of

`sum`, add

`i`to it, and then use that result to modify

`sum`.

Everything on the right-hand side of the '=' sign is based on the

*old*value of

`sum`, but after the statement has completed,

`sum`will be updated with the new value.

In some languages (eg, C/C++) these are called 'lvalue's and 'rvalue's ('l' and 'r' being short for 'left' and 'right').

HIH

Winston

Articles by Winston can be found here

Kareem Adams

Greenhorn

Posts: 6

It is sorta covered in the JavaRanch Style Guide. |