stringstream Help...

This is a discussion on stringstream Help... within the C++ Programming forums, part of the General Programming Boards category; Hello all- I need to take the first few lines on standard input and print it out. However, I need ...

  1. #1
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    Question stringstream Help...

    Hello all-

    I need to take the first few lines on standard input and print it out. However, I need to check them against some conditions. I have stored the first line in a string vector and then converted to a string stream in preparation for the second line. The following fails:
    Code:
    n.clear();
    while(getline(cin,n)) {
    v.push_back(n);
    if(v[0] != "P2"){
    exit(1); //Works up to this point
    }
    
    stringstream ss(n);
    ss >> a;
    iv.push_back(n);
    if(a < 0)
    exit(1);
    }
    This fails. Some help would be appreciated.
    Last edited by neogst; 02-07-2011 at 02:38 PM.

  2. #2
    Registered User whiteflags's Avatar
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    Quote Originally Posted by man exit
    void exit(int status);

    The exit() function causes normal process termination and the value of status & 0377 is returned to the parent
    You sure that's what you want? Your problem would be solved if you found some other way besides exit. Like, returning 0;

  3. #3
    and the hat of wrongness Salem's Avatar
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    Fails how?

    Doesn't compile?
    Exits when it shouldn't?
    Doesn't exit when it should?

    What type is a?

    What did you actually type in to make it pass/fail?

    Post a short and complete example, and the input you type in, if you want a fast and accurate answer.
    A few random lines of code without any context just draws a load of questions.

    And remember the code tags!
    If you dance barefoot on the broken glass of undefined behaviour, you've got to expect the occasional cut.
    If at first you don't succeed, try writing your phone number on the exam paper.
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  4. #4
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    Here is my code. Second if statement fails

    Code:
    #include<cstdio>
    #include<cstdlib>
    #include<vector>
    #include<string>
    #include<iostream>
    #include<sstream>
    #include<cmath>
    using namespace std;
    
    main() {
    
    
    int a;
    int check;
    string n, m, s;
    vector <string> v;
    vector <int> iv;
    
    
    n.clear();
    while(getline(cin,n)){
        v.push_back(n);
                                                                  
    
    
    vector <string> v;
    vector <int> iv;
    
    
    n.clear();
    while(getline(cin,n)){
        v.push_back(n);
        n.clear();
        if(v[0]!= "P2"){
            return 0;
                        }
        //stringstream ss(n);
        //ss >> a;
    //  v.push_back(n);
         a = atoi(n.c_str());
        stringstream ss(n);
        ss >> a;
        if (a <0){
            return 0;
        }
    
    }
    }
    Last edited by neogst; 02-07-2011 at 02:39 PM.

  5. #5
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    What do you mean by "Second if statement fails" do you mean that it always executes or never executes. Also please notice the third line after your while
    Code:
     n.clear();
    this clears (erases) anything that was in your variable n so when you get to your stringstream there is nothing in your variable 'n'.

    Jim
    Last edited by jimblumberg; 02-08-2011 at 09:40 AM.

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