Search for .txt file

This is a discussion on Search for .txt file within the C++ Programming forums, part of the General Programming Boards category; I would like to know if there is any way that the user could enter a filename and have my ...

  1. #1
    Registered User L_U_K_E's Avatar
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    Search for .txt file

    I would like to know if there is any way that the user could enter a filename and have my program open the file.The thing is all of the files already exist and i want my prog to search for the file and then open it.

    I was thinking maybe something like this:
    Code:
    case 1:
    {
       cout<<"enter filename:";
       getline(cin,filename);
       ofstream a_file("Ingrediants\\"<<filename<<".txt";
       a_file>> information;
       a_file.close();
       cout<<information;
    }
    But im not sure this will work because of the:
    Code:
       ofstream a_file("Ingrediants\\"<<filename<<".txt";
    part of the file.

  2. #2
    C++ Witch laserlight's Avatar
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    I think it should be:
    Code:
    ofstream a_file(("Ingrediants\\" + filename + ".txt").c_str());
    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

  3. #3
    Devil's Advocate SlyMaelstrom's Avatar
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    Code:
    getline(cin,filename);
    filename = "Ingrediants\\" + filename + ".txt";
    a_file.open(filename.c_str());
    EDIT: Though perhaps laserlight's suggestion would be better assuming you want to maintain the integrity of the original file name.
    Sent from my iPadŽ

  4. #4
    Registered User L_U_K_E's Avatar
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    Thanx for both of your help ill try them when i get home(lol)!

  5. #5
    Registered User L_U_K_E's Avatar
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    Right i can now open the file but why wont this piece of code work:
    Code:
    getline(file1,info1);
    this works
    Code:
    getline(cin,info1);
    but this accepts user input but i want to read in the first line of the file and then do whatever with it(lol).

  6. #6
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    The << operator is only overloaded (overloaded == used for special things) for stream operations like cout and cin (and file objects you create). It's not a magic C++ function.

    By the way, your line is missing a ")" in the end.
    Code:
    #include <stdio.h>
    
    void J(char*a){int f,i=0,c='1';for(;a[i]!='0';++i)if(i==81){
    puts(a);return;}for(;c<='9';++c){for(f=0;f<9;++f)if(a[i-i%27+i%9
    /3*3+f/3*9+f%3]==c||a[i%9+f*9]==c||a[i-i%9+f]==c)goto e;a[i]=c;J(a);a[i]
    ='0';e:;}}int main(int c,char**v){int t=0;if(c>1){for(;v[1][
    t];++t);if(t==81){J(v[1]);return 0;}}puts("sudoku [0-9]{81}");return 1;}

  7. #7
    C++ Witch laserlight's Avatar
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    Could be some problem with file1. How does it not work?
    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

  8. #8
    Registered User L_U_K_E's Avatar
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    well afterwards i have the line:
    Code:
    cout<<info1;
    however nothing is output onto the screen(??).

  9. #9
    Registered User L_U_K_E's Avatar
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    by the way i get the error message :

    "no matching function to call to 'getline(std:fstream&,std::string&)'

  10. #10
    C++ Witch laserlight's Avatar
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    getline() reads from an input stream. file1 is an output stream.
    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

  11. #11
    Registered User L_U_K_E's Avatar
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    i get ya (i hope), so i just need to open the file for reading from then im sorted.But how do i do that??

  12. #12
    C++ Witch laserlight's Avatar
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    so i just need to open the file for reading from then im sorted
    Use std::ifstream?
    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
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    Have you made sure that your file was opened correctly?

    Code:
    ifstream file("foobar.txt");
    if(!file.is_open() || file.bad())
    {
        cout << "Unable to open file!\n";
    }
    Code:
    #include <stdio.h>
    
    void J(char*a){int f,i=0,c='1';for(;a[i]!='0';++i)if(i==81){
    puts(a);return;}for(;c<='9';++c){for(f=0;f<9;++f)if(a[i-i%27+i%9
    /3*3+f/3*9+f%3]==c||a[i%9+f*9]==c||a[i-i%9+f]==c)goto e;a[i]=c;J(a);a[i]
    ='0';e:;}}int main(int c,char**v){int t=0;if(c>1){for(;v[1][
    t];++t);if(t==81){J(v[1]);return 0;}}puts("sudoku [0-9]{81}");return 1;}

  14. #14
    Registered User L_U_K_E's Avatar
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    Yeah i thought of that but im fairly new so well yeah!I'll try it.

  15. #15
    Registered User L_U_K_E's Avatar
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    yeah i ave checked to see if the file is open!

    but i ave aother problem (sorry about this i said i was new to this)
    Code:
                                          getline(file2,info);
                                          cout<<"Name:" + info << endl;
                                          getline(file2,info2);
                                          cout<<"Value:" + info2 << endl;
                                          getline(file2,info3);
                                          cout<<"Weight:" + info3 << endl;
                                          getline(file2,info4);
                                          cout<<"Effect 1:" + info4 << endl;
                                          getline(file2,info5);
                                          cout<<"Effect 2:" + info5 << endl;
                                          getline(file2,info6);
                                          cout<<"Effect 3:" + info6 << endl;
                                          getline(file2,info7);
                                          cout<<"Effect 4:" + info7 << endl;
                                          file2.close();
                                          cin.get();
    I was wondering what is the matter with this as it doesn't print any of the information from the file!

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