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# Thread: need help with building a function

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1. Junior Member
Join Date
May 2011
Posts
7

## need help with building a function

Hello folks,
I have a task that I cannot solve, maybe you guys can help me out .
1234=46
2222=8
These equations are false, but if you add plusses between the digits you can make them be true, like this:
12+34=46
2+2+2+2=8
You need to build a function that gets 2 numbers (the left side and the right side of the equation), puts the plusses in right places between the digits of the left number, and then returns the equation in it's true form.
It is important to notice that there can be a random number of plusses.
That's it, have any idea?

2. ## Re: need help with building a function

Generally, for homework questions, it's always a good idea to post the code that you have (even if it doesn't yet work right).

3. Junior Member
Join Date
May 2011
Posts
7

## Re: need help with building a function

I tried to write it, but the code was too long and complicated. Not to mention it didn't work. So I thought that there is an easier way for sure, maybe a trick that I don't know. Basicaly, I tried to get all the possible positions of plusses between the digits, then check if the sum matches the right number. The problem is that I have no idea how to get the collection of all of these positions.

4. Junior Member
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May 2011
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Nazareth
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5

## Re: need help with building a function

public int result (string x)
{
//string x = "1234";
string num1, num2;
int n1, n2, res;

num1=(x.Remove(2,2));
num2=(x.Remove(0, 2));
n1=int.Parse(num1);
n2=int.Parse(num2);
res = n1 + n2;
return res;
}

5. Junior Member
Join Date
May 2011
Posts
7

## Re: need help with building a function

I write on c#.
Remove is an interesting function, but it doesn't solve the task.

6. Junior Member
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Nazareth
Posts
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## Re: need help with building a function

c or c#

7. Junior Member
Join Date
May 2011
Location
Nazareth
Posts
5

## Re: need help with building a function

what is the task exactly > my function work to me very well .!!!??!!?

8. Junior Member
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9. ## Re: need help with building a function

Originally Posted by anter

If you want help with homework, you have to post the code you have written.

10. Member
Join Date
May 2011
Location
Washington State
Posts
220

## Re: need help with building a function

Here is a little console program that I think will do what you are wanting... like the others, I believe you should actually write some attempts, or at least show what you attempted, as then we can feel better about helping you out... however, I also believe you can study the code below and still learn from it, and perhaps improve on it as you gather some understanding.

Good luck!

Code:
```class Program
{
static void Main(string[] args)
{
try
{
Console.WriteLine(Test("12345", 15));
}
catch (Exception ex)
{
Console.WriteLine(ex.Message);
}

WaitForUser();
}

static string Test(string source, int answer)
{
// add placeholder for every possible + position
for (int i = 1; i < source.Length; i += 2)
source = source.Insert(i, " ");

for (int i = 1; i < source.Length; i += 2)
{
int j = i;
while (j < source.Length)
{
source = source.Remove(j, 1);
source = source.Insert(j, "+");

string formula = source.Replace(" ", "");
return formula;

j += 2;
}

source = source.Replace("+", " ");
}

return "unresolved";
}

{
string[] parts = formula.Split('+');

foreach (string part in parts)
{
int partValue = 0;
if (Int32.TryParse(part, out partValue))
}

}

static void WaitForUser()
{
Console.WriteLine("");
Console.WriteLine("Press any key to close application...");
while (!Console.KeyAvailable) ;
}

}```
Last edited by fcronin; May 19th, 2011 at 03:30 PM.

11. Junior Member
Join Date
May 2011
Posts
7

## Re: need help with building a function

Sorry I wasn't around for so long, but I still don't have a full solution to this exercise.
fcronin, thank you, your post helped me very much. But your solution doesn't check all the options, for example if the left number is 12345 and the right one is 240 (1+234+5) your solution won't find the answer, although it exists.
I will try to fix it and if I will, I'll post it here.

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