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How to convert String to One Int

following problem in C# (working in VS Community 2015):
First off, i fairly new to C#, so excuse me if that question would be an easy fix.
I have a contact sensor giving me a string of numbers (length measurement). I read them with the SystemPort Methods and cut them down to the numbers that i need with substring (as the beginning of the string, the "SR00002" is useless to me).
In the end i end up with a string like : "000.3422" or "012.2345". Now i want to convert that string to one solid int-variable that i can work with, meaning subtract values from and such.
Bsp: I want to calculate 012.234 - 000.3422 (or , instead of . but i could change that beforehand)
I already tried Parse and ConvertToInt (while iterating through the string) but the endresult is always a string.
string b = serialPort2.ReadLine();
string[] b1 = Regex.Split(b, "SR,00,002,");
string b2 = b1[1].Substring(1);
foreach (char c in b2)
{
Convert.ToInt32(c);
}
textBox2.Text = b2 + b2.GetType();
I know that when b2 will be int it can not be printed in the Textbox but ill take care of that later.
When everything is converted accordingly, ill outsource the conversion to its own method =)
The GetType is just for testing and as said shows only System.String (which i dont want). Help would be much appreaciated. I also browsed the searchfunction and google but couldnt find anything of help. I wish any possible helpers a nice day, mfg Chris.

use the int.Parse
int.Parse("123")

You need to assign the converted values to a new variable or array that takes int or other numeric values that you want.
int[] numbers = new int[b1.length];
for(int i = 0; i < b2.length; i++)
{
numbers[i] = Convert.ToInt32(b2[i]);
}

How to reverse string in C# [duplicate]

I didn't get the problem - I was trying to do a simple action:
for(i = x.Length-1, j = 0 ; i >= 0 ; i--, j++)
{
backx[j] = x[i];
}
Both are declared:
String x;
String backx;
What is the problem ? It says the error in the title...
If there is a problem - is there another way to do that?
The result (As the name 'backx' hints) is that backx will contain the string X backwards.
P.S. x is not empty - it contains a substring from another string.

Strings are immutable: you can retrieve the character at a certain position, but you cannot change the character to a new one directly.
Instead you'll have to build a new string with the change. There are several ways to do this, but StringBuilder does the job in a similar fashion to what you already have:
StringBuilder sb = new StringBuilder(backx);
sb[j] = x[i];
backx = sb.ToString();
EDIT: If you take a look at the string public facing API, you'll see this indexer:
public char this[int index] { get; }
This shows that you can "get" a value, but because no "set" is available, you cannot assign values to that indexer.
EDITx2: If you're looking for a way to reverse a string, there are a few different ways, but here's one example with an explanation as to how it works: http://www.dotnetperls.com/reverse-string

String is immutable in .NET - this is why you get the error.
You can get a reverse string with LINQ:
string x = "abcd";
string backx = new string(x.Reverse().ToArray());
Console.WriteLine(backx); // output: "dcba"

String are immuatable. You have convert to Char Array and then you would be able to modify.
Or you can use StringBuilder.
for example
char[] wordArray = word.ToCharArray();

In C# strings are immutable. You cannot "set" Xth character to whatever you want. If yo uwant to construct a new string, or be able to "edit" a string, use i.e. StringBuilder class.

Strings are immutable in C#. You can read more about it here: http://msdn.microsoft.com/en-us/library/362314fe.aspx

Both the variables you have are string while you are treating them as if they were arrays (well, they are). Of course it is a valid statement to access characters from a string through this mechanism, you cannot really assign it that way.
Since you are trying to reverse a string, do take a look at this post. It has lot of information.

public static string ReverseName( string theName)
{
string revName = string.Empty;
foreach (char a in theName)
{
revName = a + revName;
}
return revName;
}
This is simple and does not involve arrays directly.

The code below simply swaps the index of each char in the string which enables you to only have to iterate half way through the original string which is pretty efficient if you're dealing with a lot of characters. The result is the original string reversed. I tested this with a string consisting of 100 characters and it executed in 0.0000021 seconds.
private string ReverseString(string testString)
{
int j = testString.Length - 1;
char[] charArray = new char[testString.Length];
for (int i = 0; i <= j; i++)
{
if (i != j)
{
charArray[i] = testString[j];
charArray[j] = testString[i];
}
j--;
}
return new string(charArray);
}

In case you need to replace e.g. index 2 in string use this (it is ugly, but working and is easily maintainbable)
V1 - you know what you want to put their. Here you saying in pseudocode string[2] = 'R';
row3String.Replace(row3String[2], 'R');
V2 - you need to put their char R or char Y. Here string[2] = 'R' if was 'Y' or if was not stay 'Y' (this one line if needs some form of else)
row3String.Replace(row3String[2], row3String[2].Equals('Y') ? 'R' : 'Y');

Index of the string can be long?

I want to know whether we can give the index of the string as Long data type.
var i=long.Parse(Console.ReadLine());
var result = testString[i-1];
the second line giving me the error by saying that "The best overloaded method match for 'string.this[int]' has some invalid arguments."

No you can't use long for most collection types (you haven't specified what testString is).
One way to get around this would be to segregate the string into a multi-part / multi-dimension array then use a multiplier to get which part of the array to check.
For example:
Your index is 100,000 and you have an array of shorts (32,767 length)...
string[,] testString = new string[100, 32766]; //Replace this with your Initialisation / existing string
var arrayRank = (int)Math.Round((double) 100000 / 32767, 0);
var arrayIndex = (int)Math.Round((double)100000 % 32767, 0);
//Test this works.
//testString[arrayRank, arrayIndex] = "test"; - Test to see that the array range is assignable.
var result = testString[arrayRank, arrayIndex]; //Test value is what we expect
This may not be the most efficient way to go about things, but it is a workaround.

No, it cannot accept a long. The only overload accepts an int indexer. You would need to change your code to int.Parse() instead of long.Parse()

There is no way to pass long as an index of array, compiler doesn't allow that.
Workaround can be converting the long to int, this is called narrow conversion.
var result= testString[(int)i)];

Searching a string array without built in methods

If anyone can help out there, I'll be tremendously grateful.
Essentially I am working on a homework project where, for part of it, I need to search an array. The array, I currently have as a String type, but is essentially a collection of dates. (In the format 05/06/2014)
I am just about at my wits end trying to find a way to allow the user to search this array, in particular that doesn't use built in methods like array.binarysearch etc.
I tried to implement a binary search but that didn't seem to work, I can provide code if you wish to see where I'm probably going wrong. But is there perhaps a better search I should use for this string type, or should I be converting the string array into a different type?
If anyone can help I would greatly appreciated, I'm not necessarily asking for anyone to do my work for me I'd just be thrilled if someone could bump me in the right direction, as this problem has been doing my nut in. Thanks!
Current Binary Search Code:
public static void BinarySearch(string[] dateArray, string searchTerm)
{
int first = 0;
int last = dateArray.Length - 1;
int position = -1;
bool found = false;
int compCount = 0;
while (found != true && first <= last)
{
int middle = (first + last) / 2;
int comparisonSTR = string.Compare(dateArray[middle], searchTerm);
if (dateArray[middle] == searchTerm)
{
found = true;
position = middle;
compCount++;
Console.WriteLine("Your search has been found after " + compCount + "comparisons.");
}
else if (comparisonSTR > 0)
{
last = middle;
compCount++;
}
else
{
first = middle;
compCount++;
}
}
}

For an educational response, your binary search is correct*, if not very clean - like #Alex said, you only have to make sure you're comparing them as DateTimes. The problem is with the line
int comparisonSTR = string.Compare(dateArray[middle], searchTerm);
because the "string class" doesn't know what a date is so it can't really give you a datetime comparison when you're trying to search for dates. It can only give you a comparison on if one term comes alphabetically before, equal, or after another term.
Instead, if you convert them to DateTimes and use the comparer specific for DateTimes, then you should get back a comparison that you can use for binary search. You can either convert them to DateTime in-line
int comparisonSTR = DateTime.Compare(Convert.ToDateTime(searchTerm), Convert.ToDateTime(dateArray[middle]));
or convert them outside of the loop as the first thing you do in your method to make it a little easier to read
DateTime[] dates = Array.ConvertAll(dateArray, Convert.ToDateTime);
DateTime searchDate = Convert.ToDateTime(searchTerm);
while (found != true && first <= last)
{
int middle = (first + last) / 2;
int comparison = DateTime.Compare(searchDate, dates[middle]);
Other than that, you're pretty much set. You might have already solved this by now, so in that case I'm just posting it in part to explain why the string.Compare didn't work for you to convert dates in this case.
Edit: Make sure to test your edge cases (e.g. searching for not only the middle, but also the first and last elements for varying array sizes), because I suspect that your binary search may not be entirely correct on second review.

convert variable in asp.net

I wrote a piece of simple code that I dont to find what the problem.
the code is:
var sortSecurities="SELECT * FROM securities";
int total=0;
var value="";
foreach(var row in db.Query(sortSecurities))
{
value=row.lastGate;
total=Convert.ToInt32(value)*100;// here the problem with compilation..
db.Execute("INSERT INTO holding(IDgrossPortfolio,IDSecurity,totalHolding,units,buyGate) "+"VALUES (#0,#1,#2,#3,#4)",row.category,row.number,total,"100",row.lastGate);
}
what the problem with the convert?
the error is:
Exception Details: System.FormatException: Input string was not in a correct format.

value does not hold a value that can be converted to Int32. If you could do some debugging and see what the value of it is from row.lastGate, you might see what the problem is.
Also, not sure what is returned by db.Query(sortSecurities) (or really what kind of object row.lastGate is), but you can also try to change value=row.lastGate; to value=row.lastGate.ToString();

you can use try parse to check if the value actually contains a number
int total;
bool result = Int32.TryParse(value, out total);
if (result)
{
db.Execute("INSERT INTO holding(IDgrossPortfolio,IDSecurity,totalHolding,units,buyGate) "+"VALUES (#0,#1,#2,#3,#4)",row.category,row.number,total,"100",row.lastGate);
}

Your value isn't successfully being parsed by Convert.ToInt32()
Alternatively, consider using Int32.TryParse() and validate if the data is indeed the type of data you're expecting.
int result;
if(Int32.TryParse(row.lastGate, out result))
{
//row.lastGate was a valid int
total = result * 100;
}
else
{
//row.lastGate wasn't a valid int
}

Thanks you for all... I try now and found elegant answer.
Like I wrote in the comments, becouse I know that the value of row.lastGate
represent a number I don't need to check it.
So I try this and it works:
var sortSecurities="SELECT * FROM securities";
int total=0;
double value=0;
foreach(var row in db.Query(sortSecurities))
{
value=Convert.ToDouble(row.lastGate);
total=Convert.ToInt32(value)*100;//100 is default
db.Execute("INSERT INTO holding(IDgrossPortfolio,IDSecurity,totalHolding,units,buyGate) "+"VALUES (#0,#1,#2,#3,#4)",row.category,row.number,total,"100",row.lastGate);
}
Probably I needed to change the value first of all to double and then to int
Becouse when I try to change it directly to int the Compiler did'nt interpret the
string right, becouse of the dot in the number (type double).
thanks about the the intention..