Variable filename

This is a discussion on Variable filename within the C++ Programming forums, part of the General Programming Boards category; When I do something like ofstream newfile("file.txt"); in order to create a new file, how can I use a user-input ...

  1. #1
    Registered User Azmeos's Avatar
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    Variable filename

    When I do something like ofstream newfile("file.txt"); in order to create a new file, how can I use a user-input variable as the filename and add .txt to it in order to make a custom-named file?

  2. #2
    Skunkmeister Stoned_Coder's Avatar
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    Code:
    string input;
    getinput(input); // you implement
    input += ".txt";
    ofstream file(input.c_str());
    is one way to do it
    Last edited by Stoned_Coder; 06-09-2003 at 12:22 PM.
    Free the weed!! Class B to class C is not good enough!!
    And the FAQ is here :- http://faq.cprogramming.com/cgi-bin/smartfaq.cgi

  3. #3
    Registered User Azmeos's Avatar
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    Thanks, I think that will work... but another part of my code is being screwy... when I enter something for the cin, it executes the if fine, but then it skips the next cin ... I know it's because it's reading the '\n' character, but I don't know how to stop it... any suggestions?

    Here's the code for better understanding:

    Code:
    void main() {
    	char name[20];
    
    	char choice;
    
    	cout << "Load file (L) or create New file (N)?";
    	cin >> choice;
    	if (tolower(choice) == 'l') {
    
    		//Does stuff...
    
    	}else{
    
    	cout << "Please enter your name(no more than 20 letters): ";
    	cin.getline(name, 20, '\n');			//It skips this line (or rather, it enters '\n')
    
    }

  4. #4
    Registered User
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    one way is to place a call to ignore() before every call to getline(). Depending on how persnickity you want to be you can do something simple like this:

    cin >> choice;
    cin.ignore();
    getline(cin, string1);

    which will ignore just one char, or somewhat more sure would be something like this:

    cin >> choice;
    cin.ignore(1000);
    getline(cin, string1);

    which will ignore up to 1000 char or until a newline char is found, whichever comes first. The most robust way is to use the largest size int possible, which is available from the limits.h or climits file and is called something like INT_MAX. It would look something like this:

    #include <climit>
    //do dah
    cin >> choice;
    cin.ignore(INT_MAX, string1);
    getline(cin, string1);

  5. #5
    Registered User
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    >>The most robust way is to use the largest size int possible
    You need the max. possible stream size.

    Code:
        cin.ignore(numeric_limits<std::streamsize>::max(), '\n');

  6. #6
    Registered User Azmeos's Avatar
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    Thanks, that worked! I have another question ... is there a way to do a tolower() effect on a string?

  7. #7
    Registered User
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    I believe most string classes have a tolower() function that would be used somehting like this:

    string s = "Hello";
    s.tolower();
    cout << s;

    It might be called Tolower() or tolower() or toLower() or whatever, so look at your documentation. the version of tolower() in sting.h (aka cstring) is for single char only, not full C style strings.

  8. #8
    Registered User
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    For std::string you can do you something like this
    Code:
    #include <iostream>
    #include <string>
    #include <algorithm>
    #include <functional>
    
    using namespace std;
    
    int main()
    {
       string str = "Hello World";
    
       transform(str.begin(),str.end(),str.begin(),ptr_fun(::toupper));
    
       cout << str << endl;
    }

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