Thread: Adding to file

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.

>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:

getline ( cin, an_std_string );

>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:

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

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.

>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).

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:

#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;
}

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

Code:

#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;
}

Code:

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