C#

private void CycleTextBoxes()
{
     foreach( Control ctrl in gbTextBoxGroupBox.Controls)
     {
          TextBox tbTemp = (TextBox)ctrl;
          if(tbTemp!=null)
          {
               //do stuff here.....
          }
      }
}

using System.IO;
using System.Runtime.InteropServices;
using System.Text;
...
...
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public class INI
{
	public INI(string Path)
	{
		INIPath = Path;	
	}
	public string INIPath=null;
	[DllImport("kernel32")]
	private static extern long WritePrivateProfileString(string section,string key,string val,string filePath);
	[DllImport("kernel32")]
	private static extern int GetPrivateProfileString(string section,string key,string def,StringBuilder retVal,int size,string filePath);
	[DllImport("kernel32")]
	private static extern int WritePrivateProfileSection(string section,string Entries,string filePath);

	public void ClearSection(string SectionName)
	{
		WritePrivateProfileSection(SectionName,"",this.INIPath);
	}
	public void WriteINI(string Section,string Key,string Value)
	{
		WritePrivateProfileString(Section,Key,Value,this.INIPath);
	}	
	public string GetINI(string Section,string Key,string DefaultValue)
	{
		StringBuilder temp = new StringBuilder(255);
		int i = GetPrivateProfileString(Section,Key,"",temp,255,this.INIPath);
		if(i==0 && DefaultValue!="NOADD")
		{
			WriteINI(Section,Key,DefaultValue);
			return DefaultValue;
		}
		if(i==0 && DefaultValue=="NOADD")
			return "NOADD";
		return temp.ToString();
	}
}