Help Writing a Function

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Write a function called crazySum that takes an array of numbers, and returns the sum of each number multiplied by its position in the array.

For example, if you pass [4, 8, 15, 16], the program will calculate 4*1 + 8*2 + 15*3 + 16*4 and give you that back as an answer.
I am attempting to work through this by taking an x (value) and i (placement) and then using *+ to find the sum, but can't extract more than just the value.
Here is the beginning of my solution:

JavaScript

var array = [3,2,2];
crazySum = function () {
    i=1
for(var i = 1; i<array.length; i++) {
    return i
}
}
console.log(crazySum[i]+1);

Any help or links to similar queries is very much appreciated =)

Posted 25-Dec-15 9:17am

littlecodebaby

Updated 25-Dec-15 9:24am

PIEBALDconsult

v3

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Comments

PIEBALDconsult 25-Dec-15 14:24pm

You seem to be returning i too soon.

littlecodebaby 27-Dec-15 14:39pm

Thanks for reading my question @PIEBALD, my intention with returning i then was just to check what the function was doing, thinking that breaking the steps down a little would give me a chance to find errors and troubleshoot.
I see that you're very active and experienced on this site, and want to ask a favour. if you can think of any examples of functions that take arrays, could you pass me the links? I hope with exposure to more examples of similar things, I can manipulate the parts to run my function. Thank you!

ps coded thus v the function returns "undefined."
var array = [];
crazySum = function ([]) {
var sum= 0;
for (var i= 0; i< array.length;i++)
{
sum += ((i+1) * array[i]);
}
};

console.log(crazySum([2,3,2]))

Mohibur Rashid 25-Dec-15 20:00pm

Have you learned javascript? Or did you do any simple program that demonstrate hoe to get sum of array?

[no name] 26-Dec-15 8:17am

Please note first, I'm not familar with Java, so take care with my comment/syntax.
a.) I'm missing the sum you like to calculate/return
b.) Your for Loop seems to miss the first element.
Think about somthing like this:
var sum= 0;
for (var i= 0; i< array.length;i++)
{
sum= sum + (i+1) * Array[i];
}

// At this point, sum should have the value you excpect.
Do you see the differences?

littlecodebaby 27-Dec-15 12:55pm

Thank you for trying something =)
I built your code into my function but is still returning "undefined." I will let you know when I work it out (with slight changes, capitalization etc.).

ref:
var array = [];
crazySum = function () {
var sum= 0;
for (var i= 0; i< array.length;i++)
{
sum += (i+1) * array[i];
}
};

crazySum([2,3,2])

[no name] 27-Dec-15 13:15pm

Sorry that it did not help you. I suggest to use the Debugger and go step by step through the code and watch the variables.
Good luck :-)

littlecodebaby 27-Dec-15 14:39pm

Thanks! I'll check that out.

2 solutions

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This content, along with any associated source code and files, is licensed under The Code Project Open License (CPOL)

Richard MacCutchan · Answer 1 · 2015-12-25T23:15:00

Solution 1

Doesn't matter what you do the function will only ever return a value of 1. I would suggest going to JavaScript Tutorial[^] and working through the tutorials.

Posted 25-Dec-15 23:15pm

Richard MacCutchan

User 11060979 · Answer 2 · 2015-12-26T06:42:00

Finally decided to post my comment as a solution.

Please note first, I'm not familar with Java, so take care with my comment/syntax.
a.) I'm missing the sum you like to calculate/return
b.) Your for Loop seems to miss the first element.
Think about somthing like this:

JavaScript

var sum= 0;
for (var i= 0; i< array.length;i++)
{
  sum= sum + (i+1) * Array[i];
}

// At this point, sum should have the value you excpect.
Do you see the differences?

Help Writing a Function

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Help Writing a Function

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