I have this sample code and it throws an error:
std::random_device rd; // only used once to initialise engine
std::mt19937 rng(rd); // random-number engine used
std::uniform_int_distribution<int> uni(0, 7); // guaranteed unbiased
int random_integer = uni(rng);
The error is:
Error 1 error C2039: 'generate' : is not a member of
'std::random_device' c:\program files (x86)\microsoft visual studio
12.0\vc\include\random 1618 1 Life
Can somone explain me please, why is this happening? It seems to be an error in the header file and not in my code.
How can I fix it?
Thank you.
std::mt19937 has two constructors, one taking a single 32-bit unsigned value as parameter (default value 5489u), the other taking a seed-sequence (a template type) as a parameter. The latter is required to have a method called generate.
As a random_device does not have such a method, your code is not valid.
What you probably wanted to do is
std::mt19937 rng(rd());
That is extracting a value from the device and use that as a parameter.
Related
So I'm trying to compile this project : https://github.com/dmitrystu/libusb_stm32 with Segger Embedded studio which uses gcc. The process is choking on this error :
pasting formed 'u"Open source USB stack for STM32"', an invalid preprocessing token
which is caused by this line :
static const struct usb_string_descriptor manuf_desc_en = USB_STRING_DESC("Open source USB stack for STM32");
So USB_STRING_DESC is a macro :
#define USB_STRING_DESC(s) {.bLength = sizeof(CAT(u,s)),.bDescriptorType = USB_DTYPE_STRING,.wString = {CAT(u,s)}}
And CAT is a macro CAT(x,y) x##y. The intent must be to convert a string of type 8-bit char into a 16-bit Unicode type but the compiler doesn't like it. Is there some #include or compiler setting that may be missing that I have to add here? Clearly the author of this code expects it to work so there must be some fault in my setup.
Also I'm not clear on how the sizeof() operation is supposed to work here. As I understand it there is no way to get the length of a string at compile time so that operation will always return the size of a pointer.
In response to Keith's question, the gcc version is 4.2.1. Poking around the compiler settings the default option is the C99 standard, when I changed it to C11 everything compiled just fine. Thanks!
I'm working on some exercises for school.
The projects i have from my teacher work without any errors.
When i copy the code to a new project made on my computer, it shows this error:
Compiler Warning (level 3) C4996
I looked at both compiler settings and made them equal, this didn't work.
So i tried to make a project property file from my teachers project and insert it into my own project. Also this doesn't work.
Can somebody help me solving this issue?
This is the code:
#include <stdio.h>
#include <string.h>
int main(void)
{
char s1[32];
char s2[32];
strcpy(s1, "abc def.");
strcpy(s2, "ghi_x");
printf("s1=\"%s\" en s2=\"%s\"\n", s1, s2);
printf("s1 bevat %d symbolen en s2 bevat %d symbolen\n", strlen(s1), strlen(s2));
printf("De functie strcmp(s1,s2) geeft %d als functiewaarde\n", strcmp(s1, s2));
getchar();
return 0;
}
The Error I get is
Severity Code Description Project File Line Suppression State Error C4996 'strcpy': This function or variable may be unsafe. Consider using strcpy_s instead. To disable deprecation, use _CRT_SECURE_NO_WARNINGS. See online help for details
A quick Google search shows that "Compiler Warning (level 3) C4996" means you're using deprecated functions. The most likely culprits are your str* functions since they are generally unsafe. Switch to using their strn* counterparts (e.g. strncpy).
I haven't worked with C++ for several years and now I'm required to maintain a C++ project. I have the following piece of code which seems to compile in one project, but not in the other.
list.h
#include "mytype.h"
#include <set>
typedef std::set<MYTYPE> MYTYPE_LIST;
typedef MYTYPE_LIST::iterator MYTYPE_LIST_ITERATOR;
class LIST {
[...]
MYTYPE_LIST list;
};
list.cpp
void
LIST::somemethod(MYTYPE* requester)
{
MYTYPE_LIST_ITERATOR it;
for (it = list.begin(); it != list.end() ; it++ )
{
MYTYPE& info = (*it); // Error on this line
[...]
}
}
I am compiling my project with VS 2010, and I get the following errors on the marked line:
error C2440: 'initializing' : cannot convert from 'const MYTYPE' to 'MYTYPE &'
IntelliSense: qualifiers dropped in binding reference of type "MYTYPE &" to initializer of type "const MYTYPE"
I googled these errors, and as far as I understand, (*it) should not be const (because 'it' is not a ::const_iterator, see here), and therefor, I should be able to assign it to the reference variable.
In a std::set the data is the key, and since keys are constant you can't get a non-const reference.
Eventually I found that in VS 2010, Microsoft introduced a change which breaks backward compatibility with this code.
Apparently, this change was made for good reasons - modifying a set element might break the set's invariants. See here, "Problem 3: error C2662: 'NamedNumber::change_name' : cannot convert 'this' pointer from 'const NamedNumber' to 'NamedNumber &'".
The other project was compiled with and old version of Visual Studio, so we had no problem there.
Please explain me where I am wrong. I want to switch between several encoding utilities using pointer to function. I declare it like
int (*enc_routine)();
Later I switch coding utilities like
enc_routine = g723_24_encoder;
where utility by itself is something like
extern int g723_24_encoder(
int sample,
int in_coding,
struct g72x_state *state_ptr);
Everything was cute and fine on Linux, but now I am on Visual Studio 2012 and it says:
a value of type "int (*)(int sample, int in_coding, g72x_state *state_ptr)" cannot be assigned to an entity of type "int (*)()"
Thank you for help (if any)!
You need to declare the parameters for your function pointer. You can't declare it to take no parameters and set it equal to a function that requires 3 parameters. I'm shocked it worked on linux.
CString szMsg;
//Other non related code
//stOrderInfo.bstrOrderNum is defined as a _bstr_t
szMsg += ", Order: " + stOrderInfo.bstrOrderNum;
I'm converting the above from VS 6.0 to VS2k10 and I'm getting the following error (compiles in VS 6.0):
error C2593: 'operator +=' is ambiguous
What exactly does this mean and how can I fix it?
Because you've hard-coded ", Order: " the compiler is having a hard time to decide which type it should be.
The obvious type should be CString, but it might try to make it to some other string type, and add the number to it.
So it probably can't decide if it's a CString or another string type. So it can't decide what type you're adding to szMsg.
You could just use a type cast:
szMsg += (CString)(", Order: ") + (CString)((char *)(stOrderInfo.bstrOrderNum));
Cast between string types:
How to: Convert Between Various String Types
This means that compiler cannot choose which + operation to use for BSTR + char concatenations. You have a mismatch of three types: CString, _bstr_t, and char.
Try to unify all three operands to a single type, e.g. to CString
The implementation of CString::operator+= is known to have changed in Visual Studio 2010. For example in previous versions it handled embedded null characters OK, just like operator+ keeps doing, but the new version doesn't. So it might be related to this.
EDIT
Link to discussion on this topic:
http://social.msdn.microsoft.com/Forums/en-US/vcmfcatl/thread/c5d7f383-da80-4776-b9b8-a6065839bd87
Better use CString::AppendFormat. But ensure you pass correct format-specifier.