7 replies to this topic

[bexita]

Hi,

For exp, I got this text file containing & wanted to store different variables in a row under my struct:

John Son [tab] Mr [tab] CEO [tab] 98493834
Francis Ng [tab] Mr [tab] Coordinator [tab] 98493834
John Andrew [tab] Mr [tab] Application processing [tab] 98493834

My structure :

struct Staff

{

    char name;

    char title;

   char position;

};


// file.open text file & write it binary mode

Staff a;

//I want to store different variables in a row but still cannot get

while (file >>s.name)

{ file>> s.title>>s.position

}

After that I output into another text file but the content is messy. Whats wrong with my input ?
any advise? thx:crying:

Edited by Alyn, 19 October 2011 - 01:58 AM.
added code tag

[RhetoricalRuvim]

bexita said:

struct Staff

 {

 char name;

 char title;

 char position;

 };

I'm not sure if this is the problem, but aren't you supposed to use 'char name [512];' , or something, rather than 'char name;' ? Because what you currently have seems like name and title and position are one-character values.



By the way, please use CODE tags, when posting code. (For example, instead of typing:
print "Hello World!\r\n";

you type:
[NOPARSE]

print "Hello World!\r\n"; 

[/NOPARSE]

and this forum would automatically parse that, so it would turn into this:

print "Hello World!\r\n"; 

.)

[HemStar]

We cannot use a Single char variable to take too many characters.Each time you take data from file and give it as a value to char variable it replaces the old character which previously it war storing with the new character from the file.So you cannot get all the data printed out when you print that char variable it only prints the last stored value.I hope this may help you

[mebob]

Instead of 'char name', 'char title', and 'char position' (which would just be single characters) you may want to use 'string name', 'string title', and 'string position. You would also have to include the string header.

#include <string>

using namespace std;


struct Staff

{

    string name;

    string title;

    string position;

};

[Flying Dutchman]

Since you're coding in C++, why not use std::string? Also, I don't think >> and << operators will work properly on binary files.

[RhetoricalRuvim]

What's the C++ notion of fread () and fwrite () ?

[Flying Dutchman]

read() and write() methods of std::stream class.

[Muted]

bexita said:

After that I output into another text file but the content is messy. Whats wrong with my input ?
any advise? thx:crying:

Hello, bexita.

Creating file input/output with C++'s file streams (even for binary input/output) is VERY simple and relatively easy!
Here, I've taken the liberty of rewriting your program for you (with slight modifications along the way):

#include <iostream>
#include <fstream>

// You could use std::string instead of char*/char[] here as well
struct STAFF {
    char* name;
    char* title;
    char* position;

    STAFF() { }
    STAFF(char* name, char* title, char* position) : name(name), title(title), position(position) { }
};

int main() {

    // Our single, lonely employee :(
    STAFF staff("bexita", "Programmer", "Newbie");

    // A binary stream to write output to
    std::fstream file;

    // Open the file up for binary output (checking for an error state)
    file.open("staff.bin", std::ios::out | std::ios::app | std::ios::binary);
    if (!file.good()) {
        file.close();
        std::cerr << "Error opening file! Aborting program...\n";
        return 0;
    }

    // Write our single STAFF structure to the file (checking for an error state)
    file.write((char*)&staff, sizeof(STAFF));
    if (file.bad()) {
        file.close();
        std::cerr << "Error writing to file! Aborting program...\n";
        return 0;
    }

    // Close the file, and exit the program! :)
    file.close();

    return 0;
}

If you're honestly wanting to learn more about binary file input/output with C++, here are some resources to get started with:
- ostream - C++ Reference (Reference: "Unformatted output")
- C++ Binary File I/O (Bottom of the page, should jump on its own)

Google's a great resource. Have fun, and good luck (and belated merry Christmas)!! :)