Isolate int from string

Question

I have a string which is a word, then =, then a number.

e.g

"RefreshRate=75"

I want to get the integer at the end and store it in an Int. The program uses this value which is stored in an ini file, I need to isolate this value as some other values calculations are based upon it.

How can this be done?

Thank you in advance

Ooooopsss:

Sorry guys, i made a blunder.

The string is actually in the format "RefreshRate=numHz"...i.e "RefreshRate=65Hz"...Im sure this would work, however I get "Incorrect input format error since its adding the Hz as well, and this is throwingthe exception :s

Community · Accepted Answer · 2017-05-23 09:57:58Z

8

It’s easy! Just use a regular expression!

var m = Regex.Match(input, @"=\s*(-?\d+)");
if (!m.Success)
    throw new InvalidOperationException(
        "The input string does not contain a number.");
return Convert.ToInt32(m.Groups[1].Value);

This extracts the first integer that follows a = in any string. Therefore, if your input string is "Frequency2=47Hz", it will return 47.

edited May 23, 2017 at 9:57

CommunityBot

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answered Sep 8, 2010 at 14:43

Timwi

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Comments

Timwi · Accepted Answer · 2010-09-08 14:41:16Z

6

int i=Convert.ToInt32(st.Substring(st.IndexOf('=')+1))

edited Sep 8, 2010 at 14:41

Timwi

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answered Sep 8, 2010 at 14:27

AEMLoviji

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Anthony Pegram · Accepted Answer · 2010-09-08 14:59:48Z

5

If you are sure the format is word=value and is not variant, then this should work for you.

int value = int.Parse(line.Split('=').Last());

Edit: To deal with your ~~hurts~~ hertz problem

int value = int.Parse(line.Split('=').Last().Replace("Hz", ""));

edited Sep 8, 2010 at 14:59

answered Sep 8, 2010 at 14:25

Anthony Pegram

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Comments

Aliostad · Accepted Answer · 2010-09-08 14:55:11Z

4

How about:

    static int GetIntAfterEqual(string containsIntAfterEqual)
    {
        if(containsIntAfterEqual==null)
            throw new ArgumentNullException("containsIntAfterEqual");

        string[] splits = containsIntAfterEqual.Split('=');
        if (splits.Length == 2)
            return int.Parse(splits[1]);
        else
            throw new FormatException(containsIntAfterEqual);
    }

UPDATE: You said it could be "entryname=25hz". This should work for both cases:

    static int GetIntAfterEqual(string containsIntAfterEqual)
    {
        if(containsIntAfterEqual==null)
            throw new ArgumentNullException();

        Match match = Regex.Match(containsIntAfterEqual, @"[\d\w]+=([\d]+)\w*");
        if(match.Success)
            return int.Parse(match.Groups[1].Value);
        else
            throw new FormatException(containsIntAfterEqual);
    }

edited Sep 8, 2010 at 14:55

answered Sep 8, 2010 at 14:28

Aliostad

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2 Comments

brux Over a year ago

Hi, thanks for that....I had over looked smt :s the string is actually in the format "RefreshRate=numHz"...i.e "RefreshRate=65Hz"...Im sure this would work, however I get "Incorrect input format error since its adding the Hz as well, and this is throwingthe exception :s

Joel Over a year ago

then in the place of this: ` return int.Parse(splits[1]);` put this: return int.Parse(splits[1].Replace("Hz", ""); and that will remove the Hz from the end. Also, you'll need to fix the if statement

Kirk Woll · Accepted Answer · 2010-09-08 14:25:36Z

2

One way is to use string.Split:

int.Parse(s.Split("=")[1])

answered Sep 8, 2010 at 14:25

Kirk Woll

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Comments

AsifQadri · Accepted Answer · 2010-09-09 11:25:15Z

2

If you confirm about your text format in word, Then you can use this

var word="RefreshRate = 756numHZ";
         int n;
         int.TryParse(word.tolower().Replace("refreshrate","").Replace("=", "").Replace("numhz", "").Trim(), out n);

This will also handle case of blank space in your text.

edited Sep 9, 2010 at 11:25

answered Sep 8, 2010 at 15:28

AsifQadri

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Comments

Steve Michelotti · Accepted Answer · 2010-09-08 14:26:15Z

1

var line = "RefreshRate=75";
int number = int.Parse(line.Split('=')[1]);

answered Sep 8, 2010 at 14:26

Steve Michelotti

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Comments

Klaus Byskov Pedersen · Accepted Answer · 2010-09-08 14:25:30Z

0

You can do something along these lines, assuming that yourString contains the text RefreshRate=75.

int.Parse(yourString.Substring(yourString.IndexOf("=")+1));

answered Sep 8, 2010 at 14:25

Klaus Byskov Pedersen

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1 Comment

brux Over a year ago

Hi, thanks for that....I had over looked smt :s the string is actually in the format "RefreshRate=numHz"...i.e "RefreshRate=65Hz"...Im sure this would work, however I get "Incorrect input format error since its adding the Hz as well, and this is throwingthe exception :s

Conrad Frix · Accepted Answer · 2010-09-08 14:40:13Z

0

In case you don't want to deal with or checking for "RefreshRate=" or "RefreshRate==" or "RefreshRate=Foobar" You can do the following

public static class IntParseExtension
    {
        public static bool TryParseInt(this string s, out int i)
        {
            i = 0;     
            bool retVal = false;
            int index;
            string sNumber;
            index = s.IndexOf("=");
            if (index > -1)
            {
                sNumber = s.Substring(index + 1);
                if (sNumber.Length > 0)
                    retVal = int.TryParse(sNumber, out i);
            }
            return retVal;
        }
    }

answered Sep 8, 2010 at 14:40

Conrad Frix

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1 Comment

brux Over a year ago

hi mate, thanks for this, i made an error though, its actually "RefreshRate=numHz"...i.e "RefreshRate=65Hz", sry for the mistake, can you offer me further advice please?

yoav.str · Accepted Answer · 2010-09-08 14:51:32Z

-3

 class Program
{
    static void Main(string[] args)
    {
        int j = 0 ;
        bool flag = false;
        string s = "myage = 400";

        char[]c = s.ToCharArray();
        for (int i = 0; i <= s.Length -1; i++)
        {
            if ((c[i] > '0') && (c[i] < '9'))
            {
                flag = true;
            }
            if (flag)
            {
                c[j++] = c[i];
            }
        }
        //for (; j < s.Length - 1; j++)
        //{
            c[j] = '\0';

        s = new string(c,0,j);
        int num = int.Parse(s);
        Console.WriteLine("{0}",num);
        Console.ReadKey();
    }

i don't know if there's a better solution ... this one works

edited Sep 8, 2010 at 14:51

answered Sep 8, 2010 at 14:25

yoav.str

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3 Comments

Kirk Woll Over a year ago

TryParseInt? Where do you see that method?

Anthony Pegram Over a year ago

And how are you handling peeling "100" off from "foo=100"

yoav.str Over a year ago

i didnt see the full Q this one works for cases where after = you have lot of spaces and staff ...

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