Develop Reference

How to show button is pressed in UI for combination keys

Actually this post is different from this (posted by me as well). I've a phone keypad in my UI and now I'm able to show the button is pressed when its corresponding key is down.
private void NumDisplayBox_PreviewKeyDown(object sender, KeyEventArgs e)
{
switch (e.Key)
{
case Key.D0:
case Key.NumPad0:
ZeroBtn.Style = (Style) FindResource("PressedButtonStyle");
break;
case Key.D1:
case Key.NumPad1:
OneBtn.Style = (Style) FindResource("PressedButtonStyle");
break;
case Key.D2:
case Key.NumPad2:
TwoBtn.Style = (Style) FindResource("PressedButtonStyle");
break;
case Key.D3:
case Key.NumPad3:
ThreeBtn.Style = (Style) FindResource("PressedButtonStyle");
break;
case Key.D4:
case Key.NumPad4:
FourBtn.Style = (Style) FindResource("PressedButtonStyle");
break;
case Key.D5:
case Key.NumPad5:
FiveBtn.Style = (Style) FindResource("PressedButtonStyle");
break;
case Key.D6:
case Key.NumPad6:
SixBtn.Style = (Style) FindResource("PressedButtonStyle");
break;
case Key.D7:
case Key.NumPad7:
SevenBtn.Style = (Style) FindResource("PressedButtonStyle");
break;
case Key.D8:
case Key.NumPad8:
EightBtn.Style = (Style) FindResource("PressedButtonStyle");
break;
case Key.D9:
case Key.NumPad9:
NineBtn.Style = (Style) FindResource("PressedButtonStyle");
break;
}
if (((Keyboard.Modifiers & ModifierKeys.Shift) == ModifierKeys.Shift))
{
if (e.Key == Key.D3)
{
ThreeBtn.Style = (Style)FindResource("NormalButtonStyle");
HashBtn.Style = (Style)FindResource("PressedButtonStyle");
}
}
}
private void NumDisplayBox_PreviewKeyUp(object sender, KeyEventArgs e)
{
switch (e.Key)
{
case Key.D0:
case Key.NumPad0:
ZeroBtn.Style = (Style) FindResource("ButtonStyle4"); break;
case Key.D1:
case Key.NumPad1:
OneBtn.Style = (Style) FindResource("ButtonStyle4"); break;
.
.
.
}
}
The problem is when hash key (Shift + 3) or star key (Shift + 8) is down, the '3' button (for case hash key) also be pressed in UI. How can I show that only hash button is pressed on UI when Shift + 3 are down, but not hash button together with '3' button?

Check the KeyEventArgs.Modifiers property, and only handle the key-down when no modifiers are set.
Alternatively, use the TextInput or PreviewTextInput event to get the composed text instead of the actual key. This may be preferable anyway, as it will respond to any method of entering the appropriate text input, rather than relying on a specific key (for example, you won't have to have cases for all the possible keys, such as the top-row numeric keys and the numeric pad keys, as you are now).

This works for me:
//Make the button to have "pressed" feel when the corresponding key is pressed
private void NumDisplayBox_PreviewKeyDown(object sender, KeyEventArgs e)
{
if (((Keyboard.Modifiers & ModifierKeys.Shift) == ModifierKeys.Shift))
{
if (e.Key == Key.D3)
HashBtn.Style = (Style) FindResource("PressedButtonStyle");
if (e.Key == Key.D8)
StarBtn.Style = (Style) FindResource("PressedButtonStyle");
}
switch (e.Key)
{
case Key.D0:
case Key.NumPad0:
ZeroBtn.Style = (Style) FindResource("PressedButtonStyle");
break;
case Key.D1:
case Key.NumPad1:
OneBtn.Style = (Style) FindResource("PressedButtonStyle");
break;
case Key.D2:
case Key.NumPad2:
TwoBtn.Style = (Style) FindResource("PressedButtonStyle");
break;
case Key.D3:
case Key.NumPad3:
{
if (Keyboard.IsKeyDown(Key.LeftShift) || Keyboard.IsKeyDown(Key.RightShift))
ThreeBtn.Style = (Style) FindResource("ButtonStyle4");
else
ThreeBtn.Style = (Style) FindResource("PressedButtonStyle");
break;
}
case Key.D4:
case Key.NumPad4:
FourBtn.Style = (Style) FindResource("PressedButtonStyle");
break;
case Key.D5:
case Key.NumPad5:
FiveBtn.Style = (Style) FindResource("PressedButtonStyle");
break;
case Key.D6:
case Key.NumPad6:
SixBtn.Style = (Style) FindResource("PressedButtonStyle");
break;
case Key.D7:
case Key.NumPad7:
SevenBtn.Style = (Style) FindResource("PressedButtonStyle");
break;
case Key.D8:
case Key.NumPad8:
{
if (Keyboard.IsKeyDown(Key.LeftShift) || Keyboard.IsKeyDown(Key.RightShift))
EightBtn.Style = (Style) FindResource("ButtonStyle4");
else
EightBtn.Style = (Style) FindResource("PressedButtonStyle");
break;
}
case Key.D9:
case Key.NumPad9:
NineBtn.Style = (Style) FindResource("PressedButtonStyle");
break;
default:
break;
}
}
//Return back to its original style
private void NumDisplayBox_PreviewKeyUp(object sender, KeyEventArgs e)
{
switch (e.Key)
{
case Key.D0:
case Key.NumPad0:
ZeroBtn.Style = (Style) FindResource("ButtonStyle4");
break;
case Key.D1:
case Key.NumPad1:
OneBtn.Style = (Style) FindResource("ButtonStyle4");
break;
case Key.D2:
case Key.NumPad2:
TwoBtn.Style = (Style) FindResource("ButtonStyle4");
break;
case Key.D3:
case Key.NumPad3:
ThreeBtn.Style = (Style) FindResource("ButtonStyle4");
HashBtn.Style = (Style) FindResource("ButtonStyle4");
break;
case Key.D4:
case Key.NumPad4:
FourBtn.Style = (Style) FindResource("ButtonStyle4");
break;
case Key.D5:
case Key.NumPad5:
FiveBtn.Style = (Style) FindResource("ButtonStyle4");
break;
case Key.D6:
case Key.NumPad6:
SixBtn.Style = (Style) FindResource("ButtonStyle4");
break;
case Key.D7:
case Key.NumPad7:
SevenBtn.Style = (Style) FindResource("ButtonStyle4");
break;
case Key.D8:
case Key.NumPad8:
EightBtn.Style = (Style) FindResource("ButtonStyle4");
StarBtn.Style = (Style) FindResource("ButtonStyle4");
break;
case Key.D9:
case Key.NumPad9:
NineBtn.Style = (Style) FindResource("ButtonStyle4");
break;
default:
break;
}
}

Switch case statement

I am trying to create an application in C# that converts numbers in a text box to roman numerals in a label control and need to use a case statement. However one of my variable Roman gets the error message: Use of unassigned local variable 'Roman'.
Here is my code:
using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;
namespace Roman_Numeral_Converter
{
public partial class Form1 : Form
{
public Form1()
{
InitializeComponent();
}
private void btnCalc_Click(object sender, EventArgs e)
{
int Number=int.Parse(txtNum.Text); // To hold Number
string Roman; // To hold Roman Numeral
if (Number>=1 && Number <=10)
{
switch (Roman)
{
case "Number==1":
lblRoman.Text = "I";
break;
case "Number==2":
lblRoman.Text = "II";
break;
case "Number==3":
lblRoman.Text = "III";
break;
case "Number==4":
lblRoman.Text = "IV";
break;
case "Number==5":
lblRoman.Text = "V";
break;
case "Number==6":
lblRoman.Text = "VI";
break;
case "Number==7":
lblRoman.Text = "VII";
break;
case "Number==8":
lblRoman.Text = "VIII";
break;
case "Number==9":
lblRoman.Text = "IX";
break;
case "Number==10":
lblRoman.Text = "X";
break;
}
}
else
{
MessageBox.Show("Error: Invalid Input");
}
}
private void btnExit_Click(object sender, EventArgs e)
{
// Close the form.
this.Close();
}
private void btnClear_Click(object sender, EventArgs e)
{
txtNum.Text = "";
lblRoman.Text = "";
}
}
}

Your structure is a little off.
private void btnCalc_Click(object sender, EventArgs e)
{
var Number = int.Parse(txtNum.Text); // To hold Number
switch (Number)
{
case 1:
lblRoman.Text = "I";
break;
case 2:
lblRoman.Text = "II";
break;
case 3:
lblRoman.Text = "III";
break;
case 4:
lblRoman.Text = "IV";
break;
case 5:
lblRoman.Text = "V";
break;
case 6:
lblRoman.Text = "VI";
break;
case 7:
lblRoman.Text = "VII";
break;
case 8:
lblRoman.Text = "VIII";
break;
case 9:
lblRoman.Text = "IX";
break;
case 10:
lblRoman.Text = "X";
break;
default:
MessageBox.Show("Error: Invalid Input");
break;
}
}
You're using the lblRoman to hold your result, thus your Roman variable is unnecessary. Additionally, since you're interrogating every possible valid number in your switch, you can just use the default to replace your if/else structure.
I'm assuming you're doing this as an academic exercise. That being said, I would be remiss not to point to you Mosè Bottacini's solution to this problem.

This is because Roman variable is really unassigned. You should assign it before you enter the statement

try this,
when your number value like 1 so roman number is I.
private void btnCalc_Click(object sender, EventArgs e)
{
int Number = int.Parse(txtNum.Text); // To hold Number
string Roman; // To hold Roman Numeral
if (Number >= 1 && Number <= 10)
{
switch (Number)
{
case 1:
lblRoman.Text = "I";
break;
case 2:
lblRoman.Text = "II";
break;
case 3:
lblRoman.Text = "III";
break;
case 4:
lblRoman.Text = "IV";
break;
case 5:
lblRoman.Text = "V";
break;
case 6:
lblRoman.Text = "VI";
break;
case 7:
lblRoman.Text = "VII";
break;
case 8:
lblRoman.Text = "VIII";
break;
case 9:
lblRoman.Text = "IX";
break;
case 10:
lblRoman.Text = "X";
break;
}
}
else
{
MessageBox.Show("Error: Invalid Input");
}
}

Instead of switch, You can do other way using Linq which is even better.
int Number=int.Parse(txtNum.Text);
var romanList = new List<string> {"I", "II", "III", "IV", "V", "VI", "VII", "VIII", "IX", "X"};
if (Number >= 1 && Number <= 10)
lblRoman.Text = romanList.Select((r, i) => new { Roman = r, Index = i+1}).FirstOrDefault(x=> x.Index == Number).Roman;

you can replace your switch statement this way. and of course you need to assign a variable before using it.
public string GetNum(string val)
{
string res = ""; // Assign it an empty string.
var numToRom = new Dictionary<string, string>
{
{"1","I"},
{"2","II"}
//so on
};
numToRom.TryGetValue(val, out res);
return res;
}

The case, breaks, and loops with c#

My application works if I type in 1 character, such as A. It will give me 10 2's,
but I want it to work on all 10 digits I type in. What am I doing wrong?
I want it so I can type in 1800HELLO2 and it will give me all digits.
class Program
{
static void Main(string[] args)
{
int x = 0;
string userInput;
Console.WriteLine("Please enter the 10 digit telephone number. ");
userInput = Console.ReadLine();
while (x < 10)
{
switch (userInput)
{
case "1":
userInput = "1";
x++;
break;
case "A":
case "B":
case "C":
case "2":
userInput = "2";
x++;
break;
case "D":
case "E":
case "F":
case "3":
userInput = "3";
x++;
break;
case "G":
case "H":
case "I":
case "4":
userInput = "4";
x++;
break;
case "J":
case "K":
case "L":
case "5":
userInput = "5";
x++;
break;
case "M":
case "N":
case "O":
case "6":
userInput = "6";
x++;
break;
case "P":
case "Q":
case "R":
case "7":
userInput = "7";
x++;
break;
case "S":
case "T":
case "U":
case "8":
userInput = "8";
x++;
break;
case "V":
case "W":
case "X":
case "Y":
case "Z":
userInput = "9";
x++;
break;
case "0":
userInput = "0";
break;
}
Console.WriteLine(userInput);
}
}
}
}

Your user input can be any number of characters (the ReadLine() function will read N characters until you press ENTER) but your switch statement doesn't check individual characters of your input - it only checks a number of 1-character strings.
This means that even if you type 1-800-333-1111, you'll never check it because it's not a 1-character string like the various cases you have in the switch.
You need to iterate through each character one-by-one in the input string and check the individual characters. For example:
if ( userinput != null )
{
userinput = userinput.ToUpper ();
for ( int i = 0; i < userinput.Length; i++ )
{
switch ( userinput[i] )
{
case '1':
case 'A':
...
break;
...
default:
// Handle invalid characters here
break;
}
}
}
Notice that the various case values are single characters (using the '), not 1-character strings.
Do note, that it's not a very good idea to hardcode the length of the phone number as a number in the code. Different users may enter the phone numbers differently - some may use spaces or dashes as separators, some may only enter the digit. In these cases the length of the input string will be different. Some users may even accidentally enter multiple spaces or put in ( and ) for the area code.
You should validate the input before you even check or you shouldn't rely on the number of input digits as you iterate through the input.

Your approach isn't really correct. You're switching on userInput every time, when really you want to check each character in the string. Study the code below:
using System;
class Program {
static void Main(string[] args) {
Console.WriteLine("Please enter the 10 digit telephone number. ");
string userInput = Console.ReadLine();
// Maybe do some validation here, check the length etc
Char output;
foreach (Char c in userInput) {
switch (c) {
case 'A':
case 'B':
case 'C':
output = '2';
break;
case 'D':
case 'E':
case 'F':
output = '3';
break;
case 'G':
case 'H':
case 'I':
output = '4';
break;
case 'J':
case 'K':
case 'L':
output = '5';
break;
case 'M':
case 'N':
case 'O':
output = '6';
break;
case 'P':
case 'Q':
case 'R':
output = '7';
break;
case 'S':
case 'T':
case 'U':
output = '8';
break;
case 'V':
case 'W':
case 'X':
case 'Y':
case 'Z':
output = '9';
break;
default:
output = c;
break;
}
Console.Write(output);
}
Console.WriteLine();
Console.ReadLine();
}
}
We use a foreach loop so we aren't hard coding the length, which gives flexibility.

Try this instead:
class Program
{
static void Main(string[] args)
{
int x = 0;
string userInput;
Console.WriteLine("Please enter the 10 digit telephone number. ");
userInput = Console.ReadLine();
// Did the user type in more than 10 characters?
if(userInput.Length > 10)
{
// Get the first ten letters, no matter how many letters the user entered
userInput = userInput.Substring(0, 10);
}
// Force values to upper case for comparison
userInput = userInput.ToUpper();
string systemOutput = String.Empty;
foreach(var c in userInput)
{
switch (c)
{
case "1":
systemOutput += "1";
break;
case "A":
case "B":
case "C":
case "2":
systemOutput += "2";
break;
case "D":
case "E":
case "F":
case "3":
systemOutput += "3";
break;
case "G":
case "H":
case "I":
case "4":
systemOutput += "4";
break;
case "J":
case "K":
case "L":
case "5":
systemOutput += "5";
break;
case "M":
case "N":
case "O":
case "6":
systemOutput += "6";
break;
case "P":
case "Q":
case "R":
case "7":
systemOutput += "7";
break;
case "S":
case "T":
case "U":
case "8":
systemOutput += "8";
break;
case "V":
case "W":
case "X":
case "Y":
case "Z":
systemOutput += "9";
break;
case "0":
systemOutput += "0";
break;
}
}
Console.WriteLine(systemOutput);
}
}

You can take benefit of Dictionary for this purpose:
static void Main(string[] args)
{
int x = 0;
string userInput;
Console.WriteLine("Please enter the 10 digit telephone number. ");
userInput = Console.ReadLine();
Dictionary<string,string> dict = new Dictionary<string,string>();
dict.Add("1","1");
dict.Add("ABC2","2");
dict.Add("DEF3","3");
dict.Add("GHI4","4");
dict.Add("JKL5","5");
dict.Add("MNO6","6");
dict.Add("PQR7","7");
dict.Add("STU8","8");
dict.Add("VWXYZ9","9");
dict.Add("0","0");
userInput = string.Join("",userInput.Select(c=>dict.First(k=>k.Key.Contains(c)).Value).ToArray());
Console.WriteLine(userInput);
}
or even more concise:
static void Main(string[] args)
{
int x = 0;
string userInput;
Console.WriteLine("Please enter the 10 digit telephone number. ");
userInput = Console.ReadLine();
string[] s = "0,1,ABC2,DEF3,GHI4,JKL5,MNOP6,PQR7,STU8,VWXYZ9".Split(',');
userInput = string.Join("",userInput.Select(c=>s.Select((x,i)=>new{x,i})
.First(k=>k.x.Contains(c)).i).ToArray());
Console.WriteLine(userInput);
}

c# Flowchart from buttons while the program is running

I need to create while running a flow chart for string input which I get from textbox1.
the form size is 700*450, and it is allowed scroll.between each letter(char from the input string) has to be( in the output) an arrow(which is displayed on button)
*the whole chart has to be ehxibited on buttons *
for example, for this input string: 'ABZAZAZA'
for each letter there is asuitable color that the background of the button should be colored in.
the program should be "print":
A --> B --> Z --> A --> Z --> A --> Z -->
A -->
the size of arrow button: 34*23
the size of letter button: 34*29
the problem with my code, that the flowchart isn't shown
Heres the code:
public void DrawingSystem(string st)
{
shura_acid = 12;
tur_acid = 185;
for (int i = 1; i <= st.Length; i++)
{
if ((i % 7) == 0)
{
OpenNewLine();
}
CreateAcid(st[i - 1], i);
shura_acid = shura_acid + 24 + 68;
}
}
public void OpenNewLine()
{
tur_acid = tur_acid + 29 + 12;//34 because the size of button,12 because space between lines
shura_acid = 12;
}
public void CreateAcid(char letter, int i)
{
//create acid
Button acid = new Button();
acid.Location = new System.Drawing.Point(shura_acid, tur_acid);
acid.Name = "acid" + i;
acid.Size = new System.Drawing.Size(34, 29);
acid.TabIndex = 100 + i;
acid.Text = Convert.ToString(letter);
switch (letter)
{
case 'A': acid.BackColor = System.Drawing.Color.Fuchsia; break;
case 'C': acid.BackColor = System.Drawing.Color.Pink; break;
case 'D': acid.BackColor = System.Drawing.Color.Gray; break;
case 'F': acid.BackColor = System.Drawing.Color.Azure; break;
case 'G': acid.BackColor = System.Drawing.Color.Red; break;
case 'H': acid.BackColor = System.Drawing.Color.Aqua; break;
case 'I': acid.BackColor = System.Drawing.Color.Lime; break;
case 'K': acid.BackColor = System.Drawing.Color.Yellow; break;
case 'L': acid.BackColor = System.Drawing.Color.Olive; break;
case 'M': acid.BackColor = System.Drawing.Color.Coral; break;
case 'N': acid.BackColor = System.Drawing.Color.SaddleBrown; break;
case 'P': acid.BackColor = System.Drawing.Color.Teal; break;
case 'Q': acid.BackColor = System.Drawing.Color.Blue; break;
case 'R': acid.BackColor = System.Drawing.Color.Orange; break;
case 'S': acid.BackColor = System.Drawing.Color.Green; break;
case 'T': acid.BackColor = System.Drawing.Color.SteelBlue; break;
case 'V': acid.BackColor = System.Drawing.Color.DarkViolet; break;
case 'W': acid.BackColor = System.Drawing.Color.Crimson; break;
case 'X': acid.BackColor = System.Drawing.Color.MediumAquamarine; break;
default: acid.BackColor = System.Drawing.Color.Gold; break;
}
//create arrow
Button arrow = new System.Windows.Forms.Button();
arrow.Location = new System.Drawing.Point(shura_acid + 34 + 12, tur_acid);
arrow.Name = "acid" + i;
arrow.Size = new System.Drawing.Size(34, 23);
arrow.TabIndex = 100 + i;
arrow.Text = "-->";
arrow.UseVisualStyleBackColor = false;
}

I'll take a stab at it. No where in your code do I see you actually adding the acid or arrow buttons to a container.
You need something like this:
this.Controls.Add(acid);
and
this.Controls.Add(arrow);
Change this.Controls to the container you want them to appear in.

C# Console Application - Odd behaviour - char '\a'

After extensive debugging of an application, I noticed the console window would hang when searching text for the char '\a'. The goal is to strip out characters from a file. The below portion just prints the stripped output. It causes the same issue.
The console window would always hang upon exiting the program, and it would make it to the last statement of main. I removed the '\a' from the switch statement and the console application does not hang anymore. Any idea why? I still need to strip out the char '\a', but cannot get the application to work without hanging.
static void Main(string[] args)
{
string s_filename = args[0];
Read(s_filename, 0);
}
static void Read(string s_filename, int i_char)
{
try
{
char ch;
StringBuilder sb = new StringBuilder();
using (FileStream fs = new FileStream(s_filename, FileMode.Open, FileAccess.Read))
{
using (BinaryReader br = new BinaryReader(fs))
{
for (int i = 0; i < fs.Length; i++)
{
byte b_byte = br.ReadByte(); //Reads the bytes one at a time.
ch = (char)(b_byte);
if (isString(ch, i_char) || (sb.Length > 0 && ch == ' '))
sb.Append(ch);
else
{
if (sb.Length == 0)
continue;
if (sb.Length >= 4)
{
Console.WriteLine(sb);
}
sb.Length = 0;
}
}
}
}
}
catch (Exception e)
{
Console.WriteLine("Error {0}", e);
}
}
static bool isString(char c, int i) //http://msdn.microsoft.com/en-us/library/h21280bw.aspx
{
if (i == 0)
{
if (c >= 'a' && c <= 'z')
return true;
if (c >= 'A' && c <= 'Z')
return true;
if (c >= '0' && c <= '9')
return true;
switch (c)
{
case '~':
case '`':
case '!':
case '#':
case '#':
case '$':
case '%':
case '^':
case '&':
case '*':
case '(':
case ')':
case '-':
case '_':
case '+':
case '=':
case '[':
case ']':
case '{':
case '}':
case '|':
case '\\':
case ';':
case ':':
case '"':
case '\'':
case '<':
case '>':
case ',':
case '.':
case '?':
case '/':
case '\t': //Horizontal Tab
case '\v': //Vertical Tab
case '\n': //Newline
case '\f'://Formfeed
case '\r': //carriage return
case '\b': //Backspace
case '\x7f': //delete character
case '\x99': //TM Trademark
case '\a': //Bell Alert
return true;
}
}
if (i == 1)
{
if (c >= 'a' && c <= 'z')
return true;
if (c >= 'A' && c <= 'Z')
return true;
if (c >= '0' && c <= '9')
return true;
switch (c)
{
case '~':
case '`':
case '!':
case '#':
case '#':
case '$':
case '%':
case '^':
case '&':
case '*':
case '(':
case ')':
case '-':
case '_':
case '+':
case '=':
case '[':
case ']':
case '{':
case '}':
case '|':
case '\\':
case ';':
case ':':
case '"':
case '\'':
case '<':
case '>':
case ',':
case '.':
case '?':
case '/':
return true;
}
}
if (i == 2)
{
if (Char.IsLetterOrDigit(c))
return true;
switch (c)
{
case '~':
case '`':
case '!':
case '#':
case '#':
case '$':
case '%':
case '^':
case '&':
case '*':
case '(':
case ')':
case '-':
case '_':
case '+':
case '=':
case '[':
case ']':
case '{':
case '}':
case '|':
case '\\':
case ';':
case ':':
case '"':
case '\'':
case '<':
case '>':
case ',':
case '.':
case '?':
case '/':
return true;
}
}
if (i == 3)
{
if (Char.IsLetterOrDigit(c))
return true;
switch (c)
{
case '~':
case '`':
case '!':
case '#':
case '#':
case '$':
case '%':
case '^':
case '&':
case '*':
case '(':
case ')':
case '-':
case '_':
case '+':
case '=':
case '[':
case ']':
case '{':
case '}':
case '|':
case '\\':
case ';':
case ':':
case '"':
case '\'':
case '<':
case '>':
case ',':
case '.':
case '?':
case '/':
case '\t': //Horizontal Tab
case '\v': //Vertical Tab
case '\n': //Newline
case '\f'://Formfeed
case '\r': //carriage return
case '\b': //Backspace
case '\x7f': //delete character
case '\x99': //TM Trademark
case '\a': //Bell Alert
return true;
}
}
if (i == 4)
{
if (Char.IsLetterOrDigit(c))
return true;
}
if (i == 5)
{
if (c >= 'a' && c <= 'z')
return true;
if (c >= 'A' && c <= 'Z')
return true;
if (c >= '0' && c <= '9')
return true;
}
return false;
}

I don't see why your program would hang, but you haven't given us much to go on.
Maybe try replacing the '\a' with a literal 7.
See also http://asciitable.com/ for other character codes.
But I'm thinking it has to do with some other program logic, not just the '\a' in your code.

Anyway, that seems to me a better approach - try to rework your code if applicable:
using System.Linq;
bool Contains(string input)
{
var arr = new[] { '\t', '\v', '\n', '\f', '\r', '\b', '\x7f', '\x99', '\a', .. };
return arr.Any(c => input.Contains(c));
}