c# Pass a multi-line string to a function and return an array

Question

I'm new to C# programming and I'm trying to use good code practices. I know it is poor coding to use global variables in my example below, but I'm having a hard time figuring this out. So,I'm trying to accomplish two things with this question.

first of all, I am trying to figure out how to pass the text from a multi-line textbox to a function and have it return an array that I can then pass to another function for output (display/printing/saving to a file).

Second, Make my code more re-usable (by moving the globals inside the function that they are actually used in).

My question is.. How do I pass a string to a function and return an array that can then be passed to another function?

public partial class Form1 : Form
{

    string[] SignalStrengthInputArray450;
    string[] SignalStrengthOutputVar450 = new string[7];


    // cut out other functions

    private void Submit_450_Click(object sender, EventArgs e)
    {
        // ensure that input textbox is not null then call Load function
        // SignalStrenthInput_450 is the object name of a multi-line textbox
        if (!String.IsNullOrWhiteSpace(SignalStrengthInput_450.Text))
        {
            Load_Signal_Strength_Array();
        }
        else
        {
            // do something different
        }

        // additonal code for other textboxes
    }

    private void Load_Signal_Strength_Array()
    {
        // Processing Signal Strength textbox 
        SignalStrengthInputArray450 = SignalStrengthInput_450.Text.Split(new string[] { Environment.NewLine }, StringSplitOptions.None);
        foreach (string a in SignalStrengthInputArray450)
        {
            // loads some stuff into the SignalStrengthOutputArray450 array
        }
    }

}

Answer 1

You need a parameter and return type (string array), you may need to read more about Passing Parameters and return statement for returning values.

private string[] Load_Signal_Strength_Array(string signalStrengthInput_450)
{
   string[] SignalStrengthInputArray450 = SignalStrengthInput_450.Text.Split(new string[] { Environment.NewLine }, StringSplitOptions.None);
   foreach (string a in SignalStrengthInputArray450)
   {
      // loads some stuff into the SignalStrengthOutputArray450 array
   }
   return SignalStrengthInputArray450; 
}   

Method call would be like

string[] signalStrengthArray = Load_Signal_Strength_Array(SignalStrengthInput_450.Text);

Answer 2

You can return array from function:

public string[] f1(string s)
{
    return s.Split('/');
}

You can pass return value to anoter function:

public void f2(string[] p)
{
    foreach(var item in p)
       Console.WriteLine(item);
}

Use like:

public void main()
{
   f2(f1("some/delimited/string");
}

Answer 3

Why not

• have the Load_Signal_Strength_Array be a function which takes a local string as a parameter and return the reprocessed output (as array here but IList could be better)
• call this function with a simple Load_Signal_Strength_Array(SignalStrengthInput_450.Text)

Example:

private string[] Load_Signal_Strength_Array(string text)
{
    // Processing text
    var inputs = text.Split(new string[] { Environment.NewLine }, StringSplitOptions.None);
    var outputs = new List<string>();
    foreach (string a in inputs)
    {
        // loads some stuff into the output array
        // example:
        if (!string.IsNullOrEmpty(a)) outputs.add(a);
    }
    return outputs.ToArray();
}