file handling

[3li773]

Hey

I am making a program that is similar to an inventory program
and i was wondering if someone could help me or give a link on how i could, open a file to write in, and save that file as the part number, and put the amount of items inside the file for future viewing

thanks for all the help

[DNAunion2000]

/*DNAunion*/ Here's something I posted in another thread here that should get you started.



struct Person
{
char Name[40];
int Age;
char Gender;
char County[30];
};

...

Person people[20];

strcpy(people[0].Name, "Robert Jones");
people[0].Age = 25;
people[0].Gender = 'M';
strcpy(people[0].County, "Macon");

...

strcpy(people[19].Name, "Lauren Mathers");
people[19].Age = 15;
people[19].Gender = 'F';
strcpy(people[19].County, "Fair");

ofstream outfile("SomePeople.dat", ios::binary);

for (int Lcv = 0; Lcv < 20; ++Lcv)
{
outfile.write(reinterpret_cast<char*>people[Lcv], sizeof(Person));
}

...


Person peeps[20];
ifstream infile("SomePeople.dat", ios::binary);
for (int Lcv = 0; Lcv < 20; ++Lcv)
{
infile.read(reinterpret_cast<char*>peeps[Lcv], sizeof(Person));
}

[3li773]

well when i was compiling it, it said:
ISO C++ forbids

[sans-hubris]

forbids what?

[3li773]

strcpy(people[0].Name, "Robert Jones");

[stuka]

<rant>WHEN will people stop using char arrays in C++?????</rant> Seriously, the standard library provides std::string, which is easier, more robust, etc. It does make the file I/O a little more tricky (since std::string isn't fixed size), but I'd rather have complexity in ONE function rather than throughout my code!

[DNAunion2000]

/*DNAunion*/ Stuka, I originally posted the code in the C thread (where I made the C++ code mostly compatible with C).

[DNAunion2000]

3li773: well when i was compiling it, it said:
ISO C++ forbids [strcpy(people[0].Name, "Robert Jones");]

/*DNAunion*/ I just compiled the following code - clean compile and proper output.


#include <shlwapi.h>
#include <iostream>
using namespace std;

struct Person
{
char Name[40];
int Age;
char Gender;
char County[30];
};

int main()
{
Person people[20];

strcpy(people[0].Name, "Robert Jones");
people[0].Age = 25;
people[0].Gender = 'M';
strcpy(people[0].County, "Macon");

cout << people[0].Name << endl;
cout << people[0].Age << endl;
cout << people[0].Gender << endl;
cout << people[0].County << endl;

return 0;
}

[sans-hubris]

Originally posted by Stuka
<rant>WHEN will people stop using char arrays in C++?????</rant> Seriously, the standard library provides std::string, which is easier, more robust, etc. It does make the file I/O a little more tricky (since std::string isn't fixed size), but I'd rather have complexity in ONE function rather than throughout my code! Personally, I think that std::string makes even file IO pretty easy.

[stuka]

sans-hubris: well, you can't use handy sizeof() tricks, though with code I saw that's being considered for inclusion in the Boost library (dynamic_any), it would become trivial.

[3li773]

well since we're all talking here i would like to ask one more thing

i wanted to know how to put a variable in a system command like this.

int main
{

char cmd;
cin>>cmd;

system(cmd);

return 0;
}

but that does not work how could i make the variable determin the outcome

[stuka]

Your code doesn't work as posted because system() expects a string (char*), not a char.

[3li773]

Hey thanks alot