convert char array into CString?

nasaiya · #1 04-Jun-2005, 14:25

is it possible to convert a char array into a cstring?
i am trying to input strings from a file (using fstream) and i can't seem to use a cstring directly so i need to convert a char array to cstring. please help!

cable_guy_67 · #2 04-Jun-2005, 14:37

What exactly do you mean? Do you want to be able to move from a string to a char *?

Example:

CPP / C++ / C Code:

#include <string>
#include <cstring>
using std::string;

string my_string;
char* my_char_ptr;

strcpy(my_char_ptr, my_string.c_str());

Or something of that nature? This is of course not actual code but I hope it exibits what you are after.

Mark

nasaiya · #3 04-Jun-2005, 14:46

:edit: for somem reason when i try to define a string rather than a CString i get "undefined identifer" or something like that

this is basically what i'm triyng to do (this does not work)

CPP / C++ / C Code:

#include <fstream.h>

ifstream ccin;
CString cs;

ccin.open(data.dat);
ccin>>cs;
ccin.close();

the problem is that for some reason i can't use >> so i was going to use ccin.get or ccin.getline , but those require char arrays and i will have no way of knowing the size of the data being read into the variable

this is not a console app by the way if that makes a difference

ubergeek · #4 04-Jun-2005, 16:14

can you use a regular std::string instead of a CString? Not using VC++, I don't know how to use CString, but with an std::string:

CPP / C++ / C Code:

#include <fstream>
#include <string>
using namespace std;
...
ifstream ccin("data.dat");
if (ccin.is_open())
{
string data = "";
getline(ccin, data);
}
else error();

also, @cable_guy_67:
std::string::c_str member function returns a const char pointer, so you can't write to it with strcpy.

nasaiya · #5 04-Jun-2005, 16:28

well i know that getline would work with a std::string but i still can't figure out why the compiler doesn't seem to recognize the declaration of a string.

i am using vc++ and the program is a dialog based mfc app. i tried putting the #include <string> in the app class's header file and the implementation cpp file but it still doesn't seem to include it or use it. i'm trying to do the file input within the App class's constructor... could this be why it doesn't work?

ubergeek · #6 04-Jun-2005, 16:32

make sure to have somewhere

CPP / C++ / C Code:

using namespace std;

or just

CPP / C++ / C Code:

using std::string;

cable_guy_67 · #7 05-Jun-2005, 09:36

Not to be picky or anything but ...

CPP / C++ / C Code:

#include <iostream>
#include <string>
#include <cstring>
using std::string;
using std::cout;
using std::endl;

int main(){
  string my_string = "my_string";
  char my_char_ptr[] = "my_char_ptr";
  // due to lack of length checking char* MUST be longer than string
  // this is just a simple example
  strcpy(my_char_ptr, my_string.c_str());
  cout << "strcpy(my_char_ptr, my_string.c_str()) = " << my_char_ptr << endl;

  return 0;
}

My output:

Code:

ME@mycpu~/WorkArea/FLTKforum/fltkPhoneBook
$ g++ -Wall test_copy.cpp -s -o Test_Copy

ME@mycpu~/WorkArea/FLTKforum/fltkPhoneBook
$ Test_Copy
strcpy(my_char_ptr, my_string.c_str()) = my_string

ME@mycpu~/WorkArea/FLTKforum/fltkPhoneBook
$ g++ --version
g++ (GCC) 3.4.1 (cygming special)
Copyright (C) 2004 Free Software Foundation, Inc.
This is free software; see the source for copying conditions.  There is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.

Go figure, I use it all the time. fltk dosen't use <string> so I use this when placing text in a display widget which is a char*. I may have been wrong in my assumption that by CString the OP meant a char array not a type named CString. So from <string.h>

Code:

char *strcpy(char *s1, const char *s2);

Mark

ubergeek · #8 05-Jun-2005, 11:44

all right, fine. my mistake. i had the order of strcpy's parameters wrong

nasaiya · #9 05-Jun-2005, 12:45

would there happen to be a way to convert a std string to a CString or LPCTSTR? because the SetWindowText functions of some of my dialog box controls will only accept those or something in quotes but that won't work. i was able to define a std string after adding using std::string but i still can't pass the data from the string to the dialog box because of the CString/LPCTSTR requirement. any ideas?

nasaiya · #10 05-Jun-2005, 15:56

nevermind i got it-- thanks for the help

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