I have this call to the czmq api:
int rc = zsock_connect(updates, ("inproc://" + uuidStr).c_str());
(Note: uuidStr is of type std::string and zsock_connect expects a const char* as its second argument)
Which gives compiler error:
error: format not a string literal and no format arguments [-Werror=format-security]
int rc = zsock_connect(updates, ("inproc://" + uuidStr).c_str());
^
I've tried:
const char* connectTo = ("inproc://" + uuidStr).c_str();
int rc = zsock_connect(updates, connectTo);
and also
int rc = zsock_connect(updates, (const char*)("inproc://" +
uuidStr).c_str());
But the error persists.
How do I correct this?
Context; I'm trying to compile this code as a Python extension on Linux using pip install. On Windows it compiles with pip install and runs just fine, presumably that compiler is more permissive.
This function acts like printf() and friends, right? If so, you have the same problem with that that exists with printf(some_var) - if the string you're passing has format sequences in it, you get undefined behavior and bad stuff happening because there aren't the arguments present that you're telling the function to expect. The fix is to do something like:
int rc = zsock_connnect(updates, "inproc://%s", uuidStr.c_str());
Basically, give it a format that takes your string as an argument.
Related
Ok, so I'm using C++ to make a library that'd help me to print lines into a console.
So, I want to override " "(quote operators) to create an std::string instead of the string literal, to make it easier for me to append other data types to that string I want to output.
I've seen this done before in the wxWidgets with their wxString, but I have no idea how I can do that myself.
Is that possible and how would I go about doing it?
I've already tried using this code, but with no luck:
class PString{
std::string operator""(const char* text, std::size_t len) {
return std::string(text, len);
}
};
I get this error:
error: expected suffix identifier
std::string operator""(const char* text, std::size_t len) {
^~
which, I'd assume, want me to add a suffix after the "", but I don't want that. I want to only use ""(quotes).
Thanks!
You can't use "" without defining a suffix. "" is a const char* by itself either with a prefix (like L"", u"", U"", u8"", R"()") or followed by suffixes like (""s, ""sv, ...) which can be overloaded.
The way that wxString works is set and implicit constructor wxString::wxString(const char*); so that when you pass "some string" into a function it is essentially the same as wxString("some string").
Overriding operator ""X yields string literals as the other answer.
I am using Nodejs c++ addon in my nodejs project. JS calls a method defined in c++ with a string as the parameter. I couldn't get the string in c++. Below is my code in c++:
NAN_METHOD(DBNode::Test){
printf("Hello\n");
printf("%s\n", info[0]->ToString());
printf("%d\n", info[1]->ToNumber());
}
Below is my js code:
const test = require('./build/Release/test.node');
test.test('ssss', 99);
Below is the output:
$ node demo.js
Hello
?ڄ?C
-272643000
You can see from the above output that the string and integer values are not correctly printed. Is there anything wrong with my code?
Let start from numbers. ToNumber returns value of type Local<Number>. It differs from regular C-like value what printf can digest.
First of all you need unwrap Local. It is v8 pointer-like utility class.
You can do it with overrided * operator. So *(info[1]->ToNumber()) gives us v8 Number child of Value. But this is not the end of story. Now we can pull good-old int from it (*(info[1]->ToNumber())).Int32Value(). Or you can use the fact Handle ancestors override -> operator too and write like info[1]->ToNumber()->Int32Value().
String case is harder. V8 uses utf8 strings and you can use String::Utf8Value utility class to get buffer of char from it. *(String::Utf8Value(info[0]->ToString()))
Usually you do not need it in v8 addons and I suggest you work with v8 objects(like Local, String, Number, etc) in your native code.
below is the solution :--
NAN_METHOD(updateSignalValue) {
Nan::Utf8String lSignal(info[0]);
int len = lSignal.length();
if (len <= 0) {
return Nan::ThrowTypeError("arg must be a non-empty string");
}
std::cout << "\n hello lSignal value is :"<
Regards, Rakesh Kumar Jha
I write in mixed mode (C++/CLI) and I can not resolve this problem:
String ^progID = "Matrikon.OPC.Server";
CLSID clsid;
HRESULT result = CLSIDFromProgID(progID, &clsid);
error C2664: 'CLSIDFromProgID' : cannot convert parameter 1 from 'System::String ^' to 'LPCOLESTR'
How can I convert String^ to LPCOLESTR ?
Thanks!
I made another way:
// 1.
pin_ptr<const WCHAR> str = PtrToStringChars(progID);
LPCOLESTR coleString = (LPWSTR)str;
I have found that pin_ptr will be released if goes out of scope Define the Scope of Pinning Pointers and pin_ptr (C++/CLI)
This code works well for me:
// 2. this is the same like (1.)
String ^progID2 = "Matrikon.OPC.Simulation.1";// This is example of dynamic string
pin_ptr<const WCHAR> PINprogID2 = PtrToStringChars(progID2);
CLSID clsid2;
HRESULT result2 = CLSIDFromProgID(PINprogID2, &clsid2); //(LPCOLESTR, &CLSID)
Another example:
// 3.
pin_ptr<const WCHAR> sclsid3 = PtrToStringChars("{63D5F432-CFE4-11d1-B2C8-0060083BA1FB}");
CLSID clsid3;
CLSIDFromString((WCHAR*)sclsid3, &clsid3); //(LPOLESTR, &CLSID)
I am not much experienced and I am not sure if there are some lack of memory, but I think those codes are correct.
Avoid using the hammer for every nail. C++/CLI lets you just as easily use native types. So it is simply:
LPCOLESTR progid = L"Matrikon.OPC.Server";
// etc..
Non-zero odds (always say why) that you can simply use Type::GetTypeFromProgID().
First, lets convert System::String to char*
IntPtr p = Marshal::StringToHGlobalAnsi(progID);
char *pNewCharStr = static_cast<char*>(p.ToPointer());
second, casting char * to LPCOLESTR using ATL conversion macro:
LPCOLESTR converted_string = A2COLE(pNewCharStr);
I wrote a function to return the extension from a path, It looks like below:
LPTSTR GetExtension(LPCTSTR path1)
{
CString str(path1);
int length = str.ReverseFind(L'.');
str = str.Right(str.GetLength()-length);
LPTSTR extension= str.GetBuffer(0);
str.ReleaseBuffer();
return extension;
}
I checked the statement and found that extension have a valid value(.txt) while returning but when i use the following statement in main method like below
LPTSTR extension = GetExtension(L"C:\\Windows\\text.txt");
The variable extension is having the following junk values:
ﻮ
ﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮﻮ䞐瀘嗯᠀骰PꬰP⚜叕u
Can anyone tell me what is the reason behind it?
You are returning a pointer to a released buffer. And the buffer is a local variable of the function. Both big no-nos. Change the signature to
size_t GetExtension(LPCTSTR path, LPTSTR buffer, size_t bufferSize)
so that you can copy the result into buffer.
Or return a CString or std::wstring, you're using C++, not C. Using TCHAR is also a heavily outmoded way to handle strings, the last non-Unicode version of Windows died a timely death 12 years ago.
I dont have my compiler with me, but may be you are probably getting the buffer and storing a location of it. Then you release it while LPTSTR is still pointing to one location.
Or may be LPTSTR is on the stack while while you look at it inside the function. On exiting the function you are loosing it.
Our C++ lib works fine with Python2.4 using Swig, returning a C++ char* back to a python str. But this solution hit problem in Python3.0, error is:
Exception=(, UnicodeDecodeError('utf8', b"\xb6\x9d\xa.....",0, 1, 'unexpected code byte')
Our definition is like(working fine in Python 2.4):
void cGetPubModulus(
void* pSslRsa,
char* cMod,
int* nLen );
%include "cstring.i"
%cstring_output_withsize( char* cMod, int* nLen );
Suspect swig is doing a Bytes->Str conversion automatically. In python2.4 it can be implicit but in Python3.0 it's no long allowed.. Anyone got a good idea? thanks
It's rather Python 3 that does that conversion. In Python 2 bytes and str are the same thing, in Python 3 str is unicode, so something somewhere tries to convert it to Unicode with UTF8, but it's not UTF8.
Your Python 3 code needs to return not a Python str, but a Python bytes. This will not work with Python 2, though, so you need preprocessor statements to handle the differences.
I came across a similar problem. I wrote a SWIG typemap for a custom char array (an unsigned char in fact) and it got SEGFAULT when using Python 3. So I debugged the code within the typemap and I realized the problem Lennart states.
My solution to that problem was doing the following in that typemap:
%typemap(in) byte_t[MAX_FONTFACE_LEN] {
if (PyString_Check($input))
{
$1 = (byte_t *)PyString_AsString($input);
}
else if (PyUnicode_Check($input))
{
$1 = (byte_t *)PyUnicode_AsEncodedString($input, "utf-8", "Error ~");
$1 = (byte_t *)PyBytes_AS_STRING($1);
}
else
{
PyErr_SetString(PyExc_TypeError,"Expected a string.");
return NULL;
}
}
That is, I check what kind of string object PyObject is. The functions PyString_AsString() and PyUnicode_AsString() will return > 0 if its input it's an UTF- 8 string or an Unicode string respectively. If it's an Unicode string, we convert that string to bytes in the call PyUnicode_AsEncodedString() and later on we convert those bytes to a char * with the call PyBytes_AS_STRING().
Note that I vaguely use the same variable for storing the unicode string and converting it later to bytes. Despite of being that questionable and maybe, it could derive in another coding-style discussion, the fact is that I solved my problem. I have tested it out with python3 and python2.7 binaries without any problems yet.
And lastly, the last line is for replicating an exception in the python call, to inform about that input wasn't a string, either utf nor unicode.