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Thread: what is charAt(0) ?

  1. #1
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    Default what is charAt(0) ?

    Is there anybody could tell me what does this function use for?For example :

    String strTemp = JOptionPane.showInputDialog(null,"Please Enter C To Open A Current Account \n Or J To Open A Joint Account");
    switch(strTemp.charAt(0)){
    				case 'c':
    				case 'C':
                                  //code statement
                                   break;
                                  case 'j':
                                  case 'J':
     }

    Basically if i program the statement in c++ ,i would coding it in this form
    switch(strTemp)
    {
                                   case 'c':
    				case 'C':
                                  //code statement
                                   break;
                                  case 'j':
                                  case 'J':
     }

    But it won't work in java ,while i try to compile it an error prompt out mentioned that ("invalid type" in switch(strTemp)) So why ?

  2. #2
    Super Moderator Json's Avatar
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    Default Re: what is charAt(0) ?

    Hello.

    The reason for the switch statement not liking "strTemp" being passed in is because you cannot use switch for checking strings. However if you use strTemp.charAt(0) you will get the first character in the string, hence the index zero (0). We can then use the switch to check the character. Switch will take anything represented as a number of int or lower or an enum. So thats byte, short, int, char and enum.

    // Json

  3. #3
    Senile Half-Wit Freaky Chris's Avatar
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    Default Re: what is charAt(0) ?

    I think you need to learn C++ better too before making those kind of remarks.

    #include <string>
    #include <iostream>
     
    using namespace std;
     
    int main(void){
        string test = "j";
     
        switch(test){
            case 'j':
                cout << "It worked! Huh... How!";
                break;
            default:
        }
     
        retrun 0;
    }
    this is an epic fail.
    chris[at]javaprogrammingforums[dot]com

    Prifysgol Bangor University, North Wales

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    mmm.. coffee JavaPF's Avatar
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    Default Re: what is charAt(0) ?

    Quote Originally Posted by Freaky Chris View Post
    this is an epic fail.
    lol thats funny
    Please use [highlight=Java] code [/highlight] tags when posting your code.
    Forum Tip: Add to peoples reputation by clicking the button on their useful posts.

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    Java kindergarten chronoz13's Avatar
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    Default Re: what is charAt(0) ?

    wud like to add some question....

    so thats why if i want to locate a character in a string i should measure it first...? by .length() method..
    and because java is measusring strings from 1-(depends on the maximum length) while the index are '0' I have to minus-1 (so it will be 0-(max length), so if i use .charAt(0) i can locate the first character and the index wont bounce out..

    any sense?
    Last edited by chronoz13; October 10th, 2009 at 09:59 PM.

  6. #6
    Super Moderator Json's Avatar
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    Default Re: what is charAt(0) ?

    Not really

    But here goes, in most cases in Java, the index is zero based. So for instance in the charAt method you will have to use a zero to get the first character. However if you wish to do a substring between x and y only the start position is zero based but the end is not. Not sure if that makes any sense, just have a look at the API reference.

    // Json

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

    chronoz13 (October 11th, 2009)