Programming Forums > Application Development > C++

Xyhm · Apr 19th, 2006, 9:48 PM

I've just started working on a project, in which part of the code is pre-written. This line generates an error message:

using std::time;

The compiler complains that time isn't a member of std. I don't know whether it is, but that code is supposed to work. As I mentioned in the title, I'm using Visual C++ 2005 Express edition.

DaWei · Apr 19th, 2006, 9:55 PM

Did you include the appropriate header? A 'using' statement doesn't magically crap these thangies, it just announces their birth.

Xyhm · Apr 19th, 2006, 10:01 PM

First I had time and stdlib, but VC++ didn't like these so I had to change them to time.h and stdlib.h. Does that explain the error?

Edit: Actually I think is does, and that it has to do with the fact that namespace was new in C++ and *.h is from C. And it seems to work simply by excluding that using-declaration. I'm not planning on duplicating any identifier anyway.

aznluvsmc · Apr 19th, 2006, 10:28 PM

I'm not sure about VC++ but if it follows the C++ standard then you generally would include <ctime> and <cstdlib> header files. By appending a "c" to the C header filename and dropping the .h extension C++ will make available the C functions you're used to. As a note, you might still have to whatever namespace you want to use but I'm hoping someone else can clarify that since I've never done VC++.

Xyhm · Apr 19th, 2006, 10:36 PM

Quote:

Originally Posted by aznluvsmc

I'm not sure about VC++ but if it follows the C++ standard then you generally would include <ctime> and <cstdlib> header files. By appending a "c" to the C header filename and dropping the .h extension C++ will make available the C functions you're used to. As a note, you might still have to whatever namespace you want to use but I'm hoping someone else can clarify that since I've never done VC++.

Thanks, "using std::time" works fine with ctime. So we have <ctime> for C++ and <time.h> for C, but what the heck is <time> then, that was written in my code to begin with? Non-standard C++?

Twilight · Apr 20th, 2006, 12:34 AM

I got another question, on a really basic level. If in VC++, I want to have string objects, and in my program I have:

(Toggle Plain Text)

#include "stdafx.h"
#include "Form1.h"
#include "string.h"  //or <cstring> or <string>, they all give the same errors as below
   .
   .
   .
string str1 = "text";

And I get the following errors:

(Toggle Plain Text)

.\Till Program.cpp(18) : error C2065: 'string' : undeclared identifier
.\Till Program.cpp(18) : error C2146: syntax error : missing ';' before identifier 'str1'
.\Till Program.cpp(18) : error C2065: 'str1' : undeclared identifier

Could somebody tell me what I missed, because in regular C++, that should work.

nnxion · Apr 20th, 2006, 3:15 AM

In regular C++ that would not work either, you need to use the std namespace.
Cstring/string.h is not what you want, those are just functions to C strings (i.e. char arrays).

(Toggle Plain Text)

#include <iostream>
#include <string>

using namespace std;

int main()
{
	string str = "bla";
	return 0;
}

If you remove the "using namespace std" line, you will see the same errors you currently have. Alternatively you can use std::string.

DaWei · Apr 20th, 2006, 5:58 AM

Again, Visual C++ is a compiler. It works with the ordinary C++ language, the ordinary C++ libraries. Write good code, you're pooty much home free. Compilers are, of course, platform dependent. Some manufacturers include proprietary extensions. Best to steer clear of those. Some are more or less compliant with the standards. VC++ 2005 isn't too bad, in my experience.

Twilight · Apr 20th, 2006, 5:23 PM

Quote:

Originally Posted by nnxion

In regular C++ that would not work either, you need to use the std namespace.
Cstring/string.h is not what you want, those are just functions to C strings (i.e. char arrays).

(Toggle Plain Text)

#include <iostream>
#include <string>

using namespace std;

int main()
{
	string str = "bla";
	return 0;
}

If you remove the "using namespace std" line, you will see the same errors you currently have. Alternatively you can use std::string.

Got it, thanks.

Apr 19th, 2006, 9:48 PM	#1
Xyhm Programmer Join Date: Mar 2006 Posts: 60 Rep Power: 3	Problem with Visual C++ Express I've just started working on a project, in which part of the code is pre-written. This line generates an error message: using std::time; The compiler complains that time isn't a member of std. I don't know whether it is, but that code is supposed to work. As I mentioned in the title, I'm using Visual C++ 2005 Express edition.

Apr 19th, 2006, 9:55 PM	#2
DaWei Resident Grouch Join Date: Jun 2005 Posts: 6,453 Rep Power: 10	Did you include the appropriate header? A 'using' statement doesn't magically crap these thangies, it just announces their birth. __________________ Abstraction doesn't make it impossible to write bad code; it makes it possible to write superior code. Contributor's Corner: Grumpy on C++ Exceptions DaWei on Pointers

Apr 19th, 2006, 10:01 PM	#3
Xyhm Programmer Join Date: Mar 2006 Posts: 60 Rep Power: 3	First I had time and stdlib, but VC++ didn't like these so I had to change them to time.h and stdlib.h. Does that explain the error? Edit: Actually I think is does, and that it has to do with the fact that namespace was new in C++ and .h is from C. And it seems to work simply by excluding that using-declaration. I'm not planning on duplicating any identifier anyway. Last edited by Xyhm; Apr 19th, 2006 at 10:12 PM.*

Apr 20th, 2006, 12:34 AM	#6
Twilight Programmer Join Date: Apr 2006 Location: Calgary, Alberta Posts: 67 Rep Power: 3	I got another question, on a really basic level. If in VC++, I want to have string objects, and in my program I have: (Toggle Plain Text) #include "stdafx.h" #include "Form1.h" #include "string.h" //or <cstring> or <string>, they all give the same errors as below . . . string str1 = "text"; #include "stdafx.h" #include "Form1.h" #include "string.h" //or <cstring> or <string>, they all give the same errors as below . . . string str1 = "text"; And I get the following errors: (Toggle Plain Text) .\Till Program.cpp(18) : error C2065: 'string' : undeclared identifier .\Till Program.cpp(18) : error C2146: syntax error : missing ';' before identifier 'str1' .\Till Program.cpp(18) : error C2065: 'str1' : undeclared identifier .\Till Program.cpp(18) : error C2065: 'string' : undeclared identifier .\Till Program.cpp(18) : error C2146: syntax error : missing ';' before identifier 'str1' .\Till Program.cpp(18) : error C2065: 'str1' : undeclared identifier Could somebody tell me what I missed, because in regular C++, that should work.

Apr 20th, 2006, 3:15 AM	#7
nnxion Programming Guru Join Date: Jun 2005 Location: elemental plane Posts: 1,429 Rep Power: 5	In regular C++ that would not work either, you need to use the std namespace. Cstring/string.h is not what you want, those are just functions to C strings (i.e. char arrays). (Toggle Plain Text) #include <iostream> #include <string> using namespace std; int main() { string str = "bla"; return 0; } #include <iostream> #include <string> using namespace std; int main() { string str = "bla"; return 0; } If you remove the "using namespace std" line, you will see the same errors you currently have. Alternatively you can use std::string. __________________ "Employ your time in improving yourself by other men's writings, so that you shall gain easily what others have labored hard for." -- Socrates

Apr 19th, 2006, 10:28 PM	#4
aznluvsmc Hobbyist Programmer Join Date: Aug 2005 Posts: 137 Rep Power: 4	I'm not sure about VC++ but if it follows the C++ standard then you generally would include <ctime> and <cstdlib> header files. By appending a "c" to the C header filename and dropping the .h extension C++ will make available the C functions you're used to. As a note, you might still have to whatever namespace you want to use but I'm hoping someone else can clarify that since I've never done VC++.

Apr 20th, 2006, 5:58 AM	#8
DaWei Resident Grouch Join Date: Jun 2005 Posts: 6,453 Rep Power: 10	Again, Visual C++ is a compiler. It works with the ordinary C++ language, the ordinary C++ libraries. Write good code, you're pooty much home free. Compilers are, of course, platform dependent. Some manufacturers include proprietary extensions. Best to steer clear of those. Some are more or less compliant with the standards. VC++ 2005 isn't too bad, in my experience. __________________ Abstraction doesn't make it impossible to write bad code; it makes it possible to write superior code. Contributor's Corner: Grumpy on C++ Exceptions DaWei on Pointers

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Programming Forums > Application Development > C++

Problem with Visual C++ Express