Muiltiplaying with lists

John

Hi Guys,

I was wondering if it was possible to multiply lists against list and lists against doubles.

My program contains a list of randomly generated numbers(doubles), and several double values for instance "double n = 12". which are collected from user input

What im trying to do is not only muliply that n'th value with the list but with a selected value from the list.

my random gen list code is as below

double weightNo = numberHn * numberInput;

if (weightNo < 1) return;
for(double i = 1; i <= weightNo; i++) inweight.Add( - 0.5 +weight.NextDouble());

listBox4.DataSource = (inweight);

just wondering if its possible, even to multiply the value against each value in the list would be great.

Hope someone can help!

Cheers!

3 Replies

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Vulpes14y ago
inweight.Count is an int and the argument to be passed to inweight[] is also an int, so you should therefore use the int type rather than double. Don't be confused by the fact that inweight is a List of doubles.

As a general rule, it's not a good idea to use double (or float) as the loop variable type of a 'for' statement. This is because, internally, floating point numbers are not usually exact and you can get some strange errors if you rely on them being so.

In contrast ints (and the other integral types) are exact and are also faster and use less memory than floating point numbers.

Although I wouldn't recommend it, you could make your approach work with:

for (double i = 0; i < inweight.Count; i++) inweight[(int)i] *= inputs;
John14y ago
becuase i am using doubles i am doing the following

for (double i; i < inweight.Count; i++) inweight[i] *= inputs;

getting too errors. 1 about converting double to int and 2 invalid statement
Vulpes14y ago
You can multiply each value in the list by 'n' as follows:

for(int i = 0; i < inweight.Count; i++) inweight[i] *= n;