Adding to file

This is what I have so far

Code:

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void enter()
{
    char mod_name[25], version[10], desc[150], cmds[100];
   
    ifstream infile("modregister.dat");
    ofstream outfile("modregister.dat");
   
    cin.ignore(numeric_limits<streamsize>::max(), '\n');   
    cout << "Module Name: ";
    gets(mod_name);
   
    cout << "Version: ";
    gets(version);
   
    cout << "Description (less than 150 words): ";
    gets(desc);
   
    cout << "Command: ";
    gets(cmds);
   
    outfile << mod_name << ' ' << version << ' ' << desc << ' ' << cmds << '\n';
    infile.close();    // Tidying up
    outfile.close();
}

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Now everytime that function runs it will override anything inside the file. I've just added in the infile part because the function needs to read from the file. I need the program to output text onto a consecutive line everytime this function is called without erasing what's previously in there. I haven't learnt how to do this yet.

ofstream outfile("modregister.dat" , ios::app | ios::out );

Okay now that's not funny. What does that mean? It works (thanks) but I'm frustrated cause it looks so easy and I was stumped!

One more thing, is all of that fine in one function?

>What does that mean?
ios::app means to append to the current data in the file.

>One more thing, is all of that fine in one function?
Of course, though mixing C and C++ I/O will bite you eventually if you aren't careful. Better to stick with the C++ I/O and save yourself the trouble of implementing awkward workarounds.

The thing is I'm focussing mainly on coding in C++. What have I done that's in C which should be in C++?

>What have I done that's in C which should be in C++?
Technically, it's all C++. But there are parts of the C subset which should be avoided whenever possible.

>char mod_name[25], version[10], desc[150], cmds[100];
C-strings are finicky and most novices have a lot of trouble with them. C++ std::strings in the <string> header are much easier to work with and are moe intuitive more intuitive (not to mention safer, but I will anyway).

>gets(mod_name);
gets is a function that even C programmers avoid like the plague. fgets would be better, but since you should be avoiding C-strings, use the getline function instead. It is declared in <string> as well and you use it like so:

Code:

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getline ( cin, an_std_string );

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>infile.close(); // Tidying up
>outfile.close();
Just being pedantic, but this isn't necessary. Both infile and outfile are local objects. Their destructors are called when the function exits and that flushes/closes the streams.

Is

Code:

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cin.getline(str, len, '\n');

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the same thing? The book I'm reading uses gets() which is why I used it, but it's not that hard to change gets() into something else.

Quote:

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>char mod_name[25], version[10], desc[150], cmds[100];
C-strings are finicky and most novices have a lot of trouble with them. C++ std::strings in the <string> header are much easier to work with and are moe intuitive more intuitive (not to mention safer, but I will anyway).

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Err...
As I said I'm just using ways I've learnt from a book. If there's a better way of doing it then please let me know. I find this all really fascinating!

>the same thing?
No, cin.getline is for C-style strings. The kind that use arrays and a nul termination character '\0'. The string class has its own overloaded getline function. Since it requires std::strings, it makes sense to be declared in <string>:

Code:

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#include <iostream>
#include <string>

int main()
{
  string s;

  cout<<"What's your name: ";
  if ( std::getline ( std::cin, s ) )
    std::cout<<"Hello, "<< s <<'!'<<std::endl;
}

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As opposed to the C-string equivalent which is declared as a part of std::istream and can be reached from <iostream>:

Code:

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#include <iostream>

int main()
{
  char s[100];

  cout<<"What's your name: ";
  if ( std::cin.getline ( s, sizeof s ) )
    std::cout<<"Hello, "<< s <<'!'<<std::endl;
}

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If I have this in a database:

Quote:

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module1 version1 description1 command1
module2 version2 description2 command2
...

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What I want to do is read from a database containing quite a few of those and then display certain things. Basically I want to take the first chars up to the whitespace and put it in an array, then move up a character and include everything up until the next whitespace. Then I'd have the values in an 4 different arrays which I can then work with. I could then do a loop to move to the next line and pick up the next values. There must be a way to do this, but as I don't understand a thing in my C++ book on I/O systems (chapter18 - I'm on 8). Anyone help me please?

Code:

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while ( fin>> mod >> ver >> des >> com ) {
  // Process a single record
}

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