int to string - found method not working

This is a discussion on int to string - found method not working within the C++ Programming forums, part of the General Programming Boards category; Hi, I tried the following code to convert an int to a string: Code: int i = 5678; string s; ...

  1. #1
    epb
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    int to string - found method not working

    Hi,

    I tried the following code to convert an int to a string:

    Code:
    int i = 5678;
    string s;
    stringstream out;
    out << i;
    s = out.str();
    But it returns an empty string! If I print the "out" variable using
    Code:
    cout << out << endl;
    It prints "0". What could possibly be wrong? I'm using Mac OS X 10.6.1 and gcc version 4.2.1.

  2. #2
    C++ Witch laserlight's Avatar
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    Try printing s instead of out and you will probably find that out.str() did not return an empty string.
    Quote Originally Posted by Bjarne Stroustrup (2000-10-14)
    I get maybe two dozen requests for help with some sort of programming or design problem every day. Most have more sense than to send me hundreds of lines of code. If they do, I ask them to find the smallest example that exhibits the problem and send me that. Mostly, they then find the error themselves. "Finding the smallest program that demonstrates the error" is a powerful debugging tool.
    Look up a C++ Reference and learn How To Ask Questions The Smart Way

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    you can do lyke this

    int val=2635;
    char s[50];
    cout<<itoa(val,s,10)<<endl;

    is that you want?

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    Quote Originally Posted by joseCarlos View Post
    you can do lyke this

    int val=2635;
    char s[50];
    cout<<itoa(val,s,10)<<endl;

    is that you want?
    Except that's C and not defined in ANSI-C nor a part of C++?

  5. #5
    epb
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    Quote Originally Posted by laserlight View Post
    Try printing s instead of out and you will probably find that out.str() did not return an empty string.
    Sorry if I wasn't clear about this.. I have already tried printing out 's', and that revealed an empty string (which is why I concluded that the code returns an empty string).

    Quote Originally Posted by joseCarlos
    you can do lyke this

    Code:
    int val=2635;
    char s[50];
    cout<<itoa(val,s,10)<<endl;
    is that you want?
    No that is not what I want.. I want to convert the int directly to a C++ string (of the string class)

  6. #6
    C++ Witch laserlight's Avatar
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    Quote Originally Posted by epb
    Sorry if I wasn't clear about this.. I have already tried printing out 's', and that revealed an empty string (which is why I concluded that the code returns an empty string).
    Okay, so given this program:
    Code:
    #include <string>
    #include <sstream>
    #include <iostream>
    
    int main()
    {
        using namespace std;
        int i = 5678;
        string s;
        stringstream out;
        out << i;
        s = out.str();
        cout << s << endl;
    }
    Compile and run it. What output do you get?
    Quote Originally Posted by Bjarne Stroustrup (2000-10-14)
    I get maybe two dozen requests for help with some sort of programming or design problem every day. Most have more sense than to send me hundreds of lines of code. If they do, I ask them to find the smallest example that exhibits the problem and send me that. Mostly, they then find the error themselves. "Finding the smallest program that demonstrates the error" is a powerful debugging tool.
    Look up a C++ Reference and learn How To Ask Questions The Smart Way

  7. #7
    epb
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    Quote Originally Posted by laserlight View Post
    Okay, so given this program:
    Code:
    #include <string>
    #include <sstream>
    #include <iostream>
    
    int main()
    {
        using namespace std;
        int i = 5678;
        string s;
        stringstream out;
        out << i;
        s = out.str();
        cout << s << endl;
    }
    Compile and run it. What output do you get?
    I get no output. If I add
    Code:
    cout << out << endl;
    after the assignment of 'i' to 'out' I get '0' as a single output.

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    Quote Originally Posted by epb View Post
    I get no output. If I add
    Code:
    cout << out << endl;
    after the assignment of 'i' to 'out' I get '0' as a single output.

    Check this out

    Code:
    #include <string>
    #include <sstream>
    #include <iostream>
    
    int main()
    {
      using namespace std;
      int i = 5678;
      string s;
      stringstream out;
      out << i;
      cout << out.str() << endl;
      s = out.str();
      cout << s << endl;
    }

  9. #9
    epb
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    Quote Originally Posted by RockyMarrone View Post
    Check this out

    Code:
    #include <string>
    #include <sstream>
    #include <iostream>
    
    int main()
    {
      using namespace std;
      int i = 5678;
      string s;
      stringstream out;
      out << i;
      cout << out.str() << endl;
      s = out.str();
      cout << s << endl;
    }
    This is also gives me an empty output

    EDIT: The output is two empty lines, so I guess you can say that the output is not completely empty
    Last edited by epb; 10-26-2009 at 08:28 AM.

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    Quote Originally Posted by epb View Post
    This is also gives me an empty output

    EDIT: This gives me two empty lines, so I guess you can say that the output is not entirely empty
    I don't know why you are not getting the output but see my shell here

    and for your information i m on linux 2.6.29.4 and gcc 4.3.2

    [rocky@localhost test]$ ls
    a.out test.cc
    [rocky@localhost test]$ cat test.cc
    Code:
    #include <string>
    #include <sstream>
    #include <iostream>
    
    int main()
    {
      using namespace std;
      int i = 5678;
      string s;
      stringstream out;
      out << i;
      cout << out.str() << endl;
      s = out.str();
      cout << s << endl;
    }
    [rocky@localhost test]$ g++ test.cc
    .[rocky@localhost test]$ ./a.out
    5678
    5678

  11. #11
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    According to this thread:

    Cocoabuilder - (Dmitry Markman) ostringstream problem with Xcode 3.2

    Assuming you're using Xcode, try setting it to build as Release rather than Debug?

  12. #12
    C++ Witch laserlight's Avatar
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    Quote Originally Posted by epb
    after the assignment of 'i' to 'out' I get '0' as a single output.
    hmm... that should imply that the stringstream is in a failed state, which is strange.
    Quote Originally Posted by Bjarne Stroustrup (2000-10-14)
    I get maybe two dozen requests for help with some sort of programming or design problem every day. Most have more sense than to send me hundreds of lines of code. If they do, I ask them to find the smallest example that exhibits the problem and send me that. Mostly, they then find the error themselves. "Finding the smallest program that demonstrates the error" is a powerful debugging tool.
    Look up a C++ Reference and learn How To Ask Questions The Smart Way

  13. #13
    epb
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    Quote Originally Posted by JacobN View Post
    According to this thread:

    Cocoabuilder - (Dmitry Markman) ostringstream problem with Xcode 3.2

    Assuming you're using Xcode, try setting it to build as Release rather than Debug?
    Yes I am using Xcode. And that worked! Thanks

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