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Thread: how to add strings as numbers?

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    Default how to add strings as numbers?

    hey

    i am trying to add two strings as numbers, as an exampel :

    String numb1 ="30";
    String numb2 ="30";

    where the answer would be 60 and not 3030. any ideas how to do that ?


  2. #2
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    Default Re: how to add strings as numbers?

    Quote Originally Posted by Dixxon View Post
    i am trying to add two strings as numbers, as an exampel :

    String numb1 ="30";
    String numb2 ="30";

    where the answer would be 60 and not 3030. any ideas how to do that ?
    Convert (better to say "parse") String to int. See parseInt, static method of java.lang.Integer.
    Andrea, www.andbin.net SCJP 5 (91%) SCWCD 5 (94%)

    Useful links for Java beginners My new project Java Examples on Google Code

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    Default Re: how to add strings as numbers?

    will that work ? as the method i am using is a string method , looks like this
    public static String add (String numb1, String nub2) 
     {
    	 // any code
     }

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    Default Re: how to add strings as numbers?

    Quote Originally Posted by Dixxon View Post
    will that work ?
    How/where you encapsulate the sum of two string-numbers is not very much important. The important base concept is the conversion from String to int (or long or double or other primitive, you can choose). And I repeat: see the parseInt method of Integer.
    Andrea, www.andbin.net SCJP 5 (91%) SCWCD 5 (94%)

    Useful links for Java beginners My new project Java Examples on Google Code

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    Default Re: how to add strings as numbers?

    i think it would look like :
     public static String addera (String tal1, String tal2) 
     {
    	 String Numb1= "30";
    	 String Numb2 ="30";
    	 int IntNumb1 = Integer.parseInt(Numb1);
    	 int IntNumb2 = Integer.parseInt(Numb2);
    	 return(IntNumb1 + IntNumb2);
     // gives an error "Type mismatch: cannot convert from int to String"
     }

    PS: i am new to java so excuse my questions....

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    Default Re: how to add strings as numbers?

    Quote Originally Posted by Dixxon View Post
    i think it would look like :
     return(IntNumb1 + IntNumb2);
     // gives an error "Type mismatch: cannot convert from int to String"
    return "" + IntNumb1 + IntNumb2;

    or (better)

    return Integer.toString(IntNumb1 + IntNumb2);

    or also (Integer.toString is called under the hood)

    return String.valueOf(IntNumb1 + IntNumb2);
    Andrea, www.andbin.net SCJP 5 (91%) SCWCD 5 (94%)

    Useful links for Java beginners My new project Java Examples on Google Code

  7. The Following User Says Thank You to andbin For This Useful Post:

    Dixxon (December 8th, 2013)

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    Default Re: how to add strings as numbers?

    oh yeah thanks , i got it work with String.valueOf()

    but while adding 3333333333333 + 3 it gives me an error :

    Exception in thread "main" java.lang.NumberFormatException: For input string: "3333333333"
    at java.lang.NumberFormatException.forInputString(Unk nown Source)
    at java.lang.Integer.parseInt(Unknown Source)
    at java.lang.Integer.parseInt(Unknown Source)
    at OperationerMedNaturligaHeltalGivnaSomTeckenstranga r.addera(OperationerMedNaturligaHeltalGivnaSomTeck enstrangar.java:60)
    at OperationerMedNaturligaHeltalGivnaSomTeckenstranga r.main(OperationerMedNaturligaHeltalGivnaSomTecken strangar.java:19)

    any ideas?

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    Default Re: how to add strings as numbers?

    Quote Originally Posted by Dixxon View Post
    but while adding 3333333333333 + 3 it gives me an error :

    Exception in thread "main" java.lang.NumberFormatException: For input string: "3333333333"
    3333333333333 is more than the largest int value. An int is 32 bit, ranges from -2147483648 to +2147483647.

    Quote Originally Posted by Dixxon View Post
    any ideas?
    Use long (64 bit). And please, see Long.parseLong method.
    Andrea, www.andbin.net SCJP 5 (91%) SCWCD 5 (94%)

    Useful links for Java beginners My new project Java Examples on Google Code

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