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Can't update variable in a do while loop [closed]

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Console.WriteLine("Would you like to go first or second?");
string firstSecond = Console.ReadLine().ToUpper();
if (firstSecond == "FIRST")
{
Console.WriteLine("1");
}
else if (firstSecond == "SECOND")
{
Console.WriteLine("2");
}
else
{
string input = "x";
bool first = input == "FIRST";
bool second = input == "SECOND";
do
{
Console.WriteLine("Please say first or second:");
input = Console.ReadLine().ToUpper();
}
while (!(first | second));
}
The do while loop keeps on going even if I type first or second, I tried changing how I state the boolean but nothing seems to work. I am new so I am might some silly mistakes. How do I fix this?

You must put first and second condition into do while loop.
string input;
bool first;
bool second;
do {
Console.WriteLine("Please say first or second:");
input = Console.ReadLine().ToUpper();
first = input == "FIRST";
second = input == "SECOND";
}
while (!(first || second));

C# indexof is entering if statement when it should not based on the List i have [closed]

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So this should be super simple , perhaps indexOf is not the way to go
var incoming = "MDd"; // incoming data
List<string> cities = new List<string>();
cities.Add("MD");
cities.Add("Mumbai");
cities.Add("Berlin");
cities.Add("Istanbul");
if(cities.IndexOf(incoming) != 1 )
{
Console.WriteLine("found");
}
else
{
Console.WriteLine("not found");
}
I am seeing "found" with linqpad output , whether it is correct "MD" or "MDd" why? and what do I change to fix this?

From the documentation of IndexOf:
Return Value The zero-based index position of value if that string is
found, or -1 if it is not. If value is String.Empty, the return value
is 0.
When value is not found in the string, it returns -1, otherwise it returns index position, which is greater than or equal to 0. So either check if index is not -1 or check if it >= 0. I personally prefer the latter one:
// if (cities.IndexOf(incoming) != -1)
if (cities.IndexOf(incoming) >= 0)
{
Console.WriteLine("found");
}

This is a typo error. You want to check for -1 rather than 1 in your if statement:
if(cities.IndexOf(incoming) != -1)
{
Console.WriteLine("found");
}
else
{
Console.WriteLine("not found");
}

I want my if loop to do nothing if certain conditions are met [closed]

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i want my if loop to do nothing when the conditions that i gave it are there
i'm new to C# and winform so i searched the internet but didnt find an answer that seems to work and right now i have no idea what to do.
,Mo
screenshot of the loop

If I understand your question correctly, you want to "cancel" all operations in the current method, right? You can use return; to do that:
if(value2 == null) return;
There is just one other thing wrong with your code: value2 will never be null.
decimal value2;
if(!decimal.TryParse(result[1], out value2)) return;
should work a lot better ;)

I can't see any loop in the code provided. You want to change Parse to TryParse and use return in order to return from the method (== do nothing):
public void button14_Click(Object sender, EventArgs e) {
string[] result = input1.Text.Split(Oprator);
//TODO: it may appear, that you want TryParse here as well
decimal value1 = decimal.Parse(result[0]);
decimal value2;
// If you have too few items, and thus you have no "value2" - do nothing
if (result.Length < 2)
return;
// Try parse result[1] to decimal; if parse fails (e.g. result[1] == "zzz") - do nothing
if (!decimal.TryParse(result[1], out value2))
return;
// you have value1, value2, Oprator; put required logic here
switch (Oprator) {
...
}
}

Have you thought about a "While" loop?
int n = 1;
while (n < 6)
{
Console.WriteLine("Current value of n is {0}", n);
n++;
}

How do I turn .Any into a for loop? [closed]

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I'm having some trouble turning the following code into a for loop. The purpose of the code is to check if the string has both a letter and a number in it.
else if (!string.Any(Char.IsLetter) || !string.Any(Char.IsDigit))
{
return false;
}
Any ideas?

Do you mean something like this?
bool anyLetter = false;
bool anyDigit = false;
foreach(var ch in str)
{
if(char.IsLetter(ch)) anyLetter = true;
if(char.IsDigit(ch)) anyDigit = true;
if(anyLetter && anyDigit) break;
}
return anyLetter || anyDigit;
Note that if this string should contain at least one digit and one letter, you need to use && instead of ||

Since Selman22 seems to have already answered the question, another solution I found is I guess you could also use RegEx:
letterCount = Regex.Matches(yourstring,#"[a-zA-Z]").Count;
numberCount = Regex.Matches(yourstring,#"\d").Count;
return letterCount != 0 && numberCount != 0;

Did you mean a loop for a set of strings?
var src = new List<string>{"A4C", "D3F", "G7I"};
var allHaveCharAndDigit = src.TrueForAll(s => s.Any(c => char.IsLetter(c)) && s.Any(c => char.IsDigit(c)));

int.TryParse() always returns true [closed]

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Closed 9 years ago.
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My program contains a textbox.
I need to check if it gets only numbers, then print.
int num;
if (this.Tree.GetType() == Main.TestInt.GetType())
{
if (int.TryParse(this.label.Text,out num) == true) // i tried without the == before
{
this.Tree.SetInfo(int.Parse(this.TextBox.Text));
base.label.Text = base.TextBox.Text;
}
else
{
base.TextBox.Text = "";
MessageBox.Show("Only Numbers Allowed", "Error");
}
}
The problem is, for some reason it always returns true, and goes to the
this.Tree.SetInfo(int.Parse(this.TextBox.Text));
Why is it happening?

2 changes:
int num;
if (this.Tree.GetType() == Main.TestInt.GetType())
{
if (int.TryParse(this.TextBox.Text,out num)) //1, you were parsing label.Text
{
this.Tree.SetInfo(num); //2, don't bother parsing it twice!
base.label.Text = base.TextBox.Text;
}
else
{
base.TextBox.Text = "";
MessageBox.Show("Only Numbers Allowed", "Error");
}
}

Probably you want to check the value of TextBox not the Label. So it would be this.TextBox.Text instead of this.Label.Text
if (int.TryParse(this.TextBox.Text,out num))
{
this.Tree.SetInfo(this.TextBox.Text);
base.label.Text = base.TextBox.Text;
}
else
{
base.TextBox.Text = string.Empty;
MessageBox.Show("Only Numbers Allowed", "Error");
}