I can't find the problem. I am trying to use char as parameter for a class template:
#include <iostream>
using namespace std;
template <class Type1, class Type2> class myclass
{
Type1 i;
Type2 j;
public:
myclass(Type1 a, Type2 b) {i=a; j=b;}
void show() { cout << i << ' ' << j << '\n'; }
};
void main()
{
myclass<int, double> ob1(10, 0.23);
myclass<char, char *> ob2('X', Just show ");
ob1.show();
ob2.show();
}
You are missing an opening quote before Just:
myclass<char, char *> ob2('X', Just show ");
// ^
// should be:
myclass<char, char *> ob2('X', "Just show");
Note though that you should use const char* when you want to allow passing string literals and that this has ownership issues. Preferrably use std::string instead.
You are missing an " in myclass<char, char *> ob2('X', Just show ");, it should be myclass<char, char*> ob2('X', "Just show ");. Furthermore the type should probably myclass<char, const char*> instead of myclass<char, char*>
Related
#include "pch.h"
#include <iostream>
#include <cstdlib>
#include <ctime>
#include <stdio.h>
using namespace std;
class LetterDistribution
{
public: char district, trace;
public: int random_num;
public : LetterDistribution(){}
public: LetterDistribution(char dis)
{
district = dis;
trace = 'Z';
}
public: string LetterNumbers()
{
random_num = rand();
string letter_no ( district + " " + random_num);
return letter_no;
}
};
int main()
{
srand(time(0));
cout << "Enter district\n"<<endl;
char dis ;
cin >> dis;
LetterDistribution ld(dis);
cout << ld.LetterNumbers();
return 0;}
I am getting error in second last line inside main "cout << ld.LetterNumbers();". I am new to c++ , I have been working on C# earlier. I shall be thankful if someone could help me .
You have 2 issues in LetterNumbers function:
You can't add to string a number, you should convert the number to string first. you can do so by std::to_string(random_num)
You can't start concatenate string with a character, since character is like number in c++, and adding anything to number is a number. You should start from a string, even an empty one.
So the whole function can be something like:
string LetterNumbers()
{
random_num = rand();
string letter_no ( std::string("") + district + " " + std::to_string(random_num));
return letter_no;
}
Another issues: (but not errors!)
in c++ you can specify public: once, and everything after it is still public, until you change it. same thing for private and protected.
instead of <stdio.h> you should use <cstdio> which is the c++ wrapper for the c header.
Is it possible to do implicit/explicit conversion between time_points of two C++11 clocks?
Motivation: chrono::durations provide means of storing time intervals from epoch, conceptually is not equal to a time_point of a custom clock that has an epoch on its own.
Having an implicit conversion between clocks eases up the use Howard Hinnant's date library <date/date.h> which provides means to manipulate and print out time_points of system clocks.
Example:
#include <date/date.h>
using namespace date;
namespace ch = std::chrono;
//
#define EPOCH_OFFSET 100
template<class Duration> using PosixTimePoint =
ch::time_point<ch::system_clock, Duration>;
typedef PosixTimePoint<ch::duration<long,std::micro>> PosixTimePointType;
struct SomeClock{
typedef ch::duration<long,std::micro> duration;
typedef ch::time_point<SomeClock> time_point;
...
static time_point now() noexcept {
using namespace std::chrono;
return time_point (
duration_cast<duration>(
system_clock::now().time_since_epoch()) + date::years(EPOCH_OFFSET) );
}
static PosixTimePoint<duration> to_posix( const time_point& tp ){...}
}
auto tp = SomeClock::now(); //<time_point<SomeClock,ch::duration<long,std::micro>>;
Objective: to convert tp so the std::stream conversions of date.h works and prints out the current time, which in my case is: 2017-12-24 17:02:56.000000
// std::cout << tp; compile error
std::cout << SomeClock::to_posix( tp ); // OK
Explicit cast: this could ease up readability, support conversion feature of the language and facilitate access to date.h routines.
long time_value = static_cast<long>( tp );
auto st = static_cast<PosixTimePointType>( tp );
std::cout << static_cast<PosixTimePointType>( tp );
I recommend mimicking the implementations of either date::utc_clock or date::tai_clock found in tz.h. For example utc_clock implements two functions to convert to and from sys_time:
template<typename Duration>
static
std::chrono::time_point<std::chrono::system_clock, typename std::common_type<Duration, std::chrono::seconds>::type>
to_sys(const std::chrono::time_point<utc_clock, Duration>&);
template<typename Duration>
static
std::chrono::time_point<utc_clock, typename std::common_type<Duration, std::chrono::seconds>::type>
from_sys(const std::chrono::time_point<std::chrono::system_clock, Duration>&);
So you can think of std::chrono::system_clock as a "hub". Any clock that implements these conversions can convert to any other clock which implements these conversions by bouncing off of system_clock under the covers. And to facilitate that bounce, date::clock_cast is introduced.
Additionally, utc_time can be used as the hub, if that is more efficient for your type. For example tai_clock implements:
template<typename Duration>
static
std::chrono::time_point<utc_clock, typename std::common_type<Duration, std::chrono::seconds>::type>
to_utc(const std::chrono::time_point<tai_clock, Duration>&) NOEXCEPT;
template<typename Duration>
static
std::chrono::time_point<tai_clock, typename std::common_type<Duration, std::chrono::seconds>::type>
from_utc(const std::chrono::time_point<utc_clock, Duration>&) NOEXCEPT;
clock_cast is smart enough to deal with this "dual-hub" system, so one can convert a clock that converts to/from utc_time, to another clock that uses sys_time as its hub.
If you also implement to_stream for your clock, then you can directly use format to format your clock::time_point. And clock_cast is likely to be useful in the implementation of your to_stream function.
Also from_stream can be used to hook your clock::time_point up to date::parse.
Search https://howardhinnant.github.io/date/tz.html for "clock_cast" for example uses of it. For your use case the to_sys/from_sys API appears to be the most useful. Just these two functions will allow you to use clock_cast between your SomeClock and any other clock in tz.h (and any other custom clock that meets these requirements).
Full Demo
#include "date/tz.h"
#include <iostream>
#include <sstream>
struct SomeClock
{
using duration = std::chrono::microseconds;
using rep = duration::rep;
using period = duration::period;
using time_point = std::chrono::time_point<SomeClock>;
static constexpr bool is_steady = false;
static time_point now() noexcept
{
return from_sys(date::floor<duration>(std::chrono::system_clock::now()));
}
static constexpr auto offset = date::sys_days{} - date::sys_days{date::year{1870}/1/1};
template<typename Duration>
static
date::sys_time<Duration>
to_sys(const std::chrono::time_point<SomeClock, Duration>& t)
{
return date::sys_time<Duration>{(t - offset).time_since_epoch()};
}
template<typename Duration>
static
std::chrono::time_point<SomeClock, Duration>
from_sys(const date::sys_time<Duration>& t)
{
return std::chrono::time_point<SomeClock, Duration>{(t + offset).time_since_epoch()};
}
};
template <class Duration>
using SomeTime = std::chrono::time_point<SomeClock, Duration>;
constexpr date::days SomeClock::offset;
template <class CharT, class Traits, class Duration>
std::basic_ostream<CharT, Traits>&
to_stream(std::basic_ostream<CharT, Traits>& os, const CharT* fmt,
const SomeTime<Duration>& t)
{
return date::to_stream(os, fmt, date::clock_cast<std::chrono::system_clock>(t));
}
template <class CharT, class Traits, class Duration>
std::basic_ostream<CharT, Traits>&
operator<<(std::basic_ostream<CharT, Traits>& os, const SomeTime<Duration>& t)
{
const CharT fmt[] = {'%', 'F', ' ', '%', 'T', CharT{}};
return to_stream(os, fmt, t);
}
template <class Duration, class CharT, class Traits, class Alloc = std::allocator<CharT>>
std::basic_istream<CharT, Traits>&
from_stream(std::basic_istream<CharT, Traits>& is, const CharT* fmt,
SomeTime<Duration>& tp, std::basic_string<CharT, Traits, Alloc>* abbrev = nullptr,
std::chrono::minutes* offset = nullptr)
{
using namespace date;
sys_time<Duration> st;
date::from_stream(is, fmt, st, abbrev, offset);
if (!is.fail())
tp = clock_cast<SomeClock>(st);
return is;
}
int
main()
{
std::cout << SomeClock::now() << '\n';
std::cout << date::format("%a, %b %d, %Y\n", SomeClock::now());
std::istringstream in{"2017-12-24 19:52:30"};
SomeClock::time_point t;
in >> date::parse("%F %T", t);
std::cout << t << '\n';
}
I'm doing a script using CAPL and am stuck for a solution to grep the login ID from Windows. Could some please help show how to get Windows user login ID from within a CAPL program code, if this is possible?
For example, if the Windows user login ID is 'kp21ml' , I want to read this ID from a CAPL function, as shown below.
byte UserIdCheck()
{
char uid[10];
byte CanMessageTrasmission;
strncpy(uid, xxxx(), 6); // where xxxx() is the unknown OS or system function that could return the login ID ?
if (strncmp(uid, "kp21ml") != 0)
{
write("Access denied!"); // Message to CANoe's Write window
CanMessageTrasmission = 0;
}
else
{
// Access ok
CanMessageTrasmission = 1;
}
return CanMessageTrasmission;
}
I use this CAPL book as my reference guide, which is very good:
http://docplayer.net/15013371-Programming-with-capl.html
But I couldn't find anything to do with system access. I would appreciate your help.
Thanks
Juno
I'm afraid you won't be able to do that directly from a CAPL script.
I generally create a CAPL-DLL and include that in my CANoe project when I need to access some OS level functionality. Though I use it mostly for accessing an external device (e.g. USB) or to interact with another program using sockets over local host, the principle is the same.
You can find more information in CANoe's documentation with examples but the CAPL-DLL source code provided in CANoe samples is a little difficult to understand.
I've attempted to strip some of the "unnecessary" parts in the following code sample; this example will create a CAPL-DLL which "exposes" the multiplyBy10 function and basically allows you to call multiplyBy10 from you CAPL script):
#define USECDLL_FEATURE
#define _BUILDNODELAYERDLL
#pragma warning( disable : 4786 )
#include "cdll.h"
#include <iostream>
#include <stdio.h>
#include <stdlib.h>
#include <map>
char moduleName[_MAX_FNAME];
HINSTANCE moduleHandle;
unsigned int
CAPLEXPORT far CAPLPASCAL multiplyBy10 (unsigned char value)
{
unsigned int result = value * 10;
freopen("CONOUT$", "w", stdout);
std::cout << "multiplyBy10() - value: " << int(value) << ", result: " << result << std::endl;
return (result);
}
CAPL_DLL_INFO4 table[] =
{
{CDLL_VERSION_NAME, (CAPL_FARCALL)CDLL_VERSION, "", "", CAPL_DLL_CDECL, 0xABD, CDLL_EXPORT},
{"multiplyBy10", (CAPL_FARCALL)multiplyBy10, "CAPL_DLL", "This is a demo function", 'L', 1, "D", "", { "value"}},
{0, 0}
};
CAPLEXPORT CAPL_DLL_INFO4 far * caplDllTable4 = table;
bool
WINAPI DllMain(HINSTANCE handle, DWORD reason, void*)
{
static FILE * stream;
switch (reason)
{
case DLL_PROCESS_ATTACH:
{
moduleHandle = handle;
char path_buffer[_MAX_PATH];
DWORD result = GetModuleFileName(moduleHandle, path_buffer, _MAX_PATH);
char drive[_MAX_DRIVE];
char dir[_MAX_DIR];
char fname[_MAX_FNAME];
char ext[_MAX_EXT];
_splitpath_s(path_buffer, drive, dir, fname, ext);
strcpy_s(moduleName, fname);
AllocConsole();
freopen_s(&stream, "conout$", "w", stdout);
std::cout << "DLL_PROCESS_ATTACH" << std::endl;
return 1;
}
case DLL_PROCESS_DETACH:
{
std::cout << "DLL_PROCESS_DETACH" << std::endl;
FreeConsole();
fclose(stream);
return 1;
}
}
return 1;
}
I'm sorry if this is vague I'm still pretty new to programming(also new to forums >_>)
Ok, my code is supposed to read in a number from a file, then use that number to read in that amount of words as dictionary words. I then store those words into an array and keep them for later usage. After the dictionary words in the file comes some paragraph, i read that in and set it to c-string array.(iv got that all down so far) But for the last part of the program i need to go back though that paragraph c-string and count how many times each dictionary word appears. I'm currently trying paragraph.find (word[0]) but i get some error that i don't know how to fix.
error: |40|error: request for member 'find' in 'paragraph', which is of non-class type 'char [2000]'|
code:
#include <iostream>
#include <fstream>
#include <cstring>
#include <windows.h>
using namespace std;
int main()
{
ifstream inStream; //declare ifstream
inStream.open("infile2.txt"); //open my file
int number; // number at the begining of the file that lets the program know
inStream >> number; // how many dictionary words are to be expected.
cout << number << " dictionary word(s)" << endl << endl;
char dict[30];
char text[2000];
char paragraph[2000]; // declareing some stuff
int count;
int position;
string word[5];
for (int i=0; i<number; i++) // using c string to set the 'number' amount of words in the dict array
{
inStream.getline(dict,30,'|');
word[i] = dict;
}
for (int i=0; i<number; i++) // cout so i can see its all set up right.
{
cout << "word " << i+1 << " is: " << word[i] << endl;
}
cout << endl;
inStream.get(paragraph,2000,'|'); // setting the rest of the paragrapg of the txt document to a c string
cout << paragraph; // so it can be searched later using the 'dict' words
position = paragraph.find (word[0]); // trying to find the position of the first word stored in 'dict[0]' but i run into an error
return 0;
}
the infile2.txt looks like this:
3steak|eggs|and|
steak and eggs and eggs and steak, eggs and steak, steak and eggs...
delicious.
c-strings are not classes and do not have a find method (or any other methods for that matter) i.e paragraph.find. You could try using a string or if you need to use c-strings a find method that takes two c strings as parameters.
such as This one
I am looking for a command line parser for Qt4.
I did a small google search, and found this: http://www.froglogic.com/pg?id=PublicationsFreeware&category=getopt however it lacks support for "--enable-foo" and "--disable-foo" switches. Besides that, it looks like a real winner.
EDIT:
It seems Frologic removed this. So the best options I see are using Boost (which is not API nor ABI stable) or forking the support for kdelibs. Yay...
QCoreApplication's constructors require (int &argc, char **argv) (and QApplication inherits from QCoreApplication). As the documentation states, it is highly recommended that
Since QApplication also deals with common command line arguments, it is usually a good idea to create it before any interpretation or modification of argv is done in the application itself.
And if you're letting Qt get the first pass at handling arguments anyways, it would also be a good idea to use QStringList QCoreApplication::arguments() instead of walking through argv; QApplication may remove some of the arguments that it has taken for its own use.
This doesn't lend itself to being very compatible with other argument-parsing libraries...
However, kdelibs does come with a nice argument parser, KCmdLineArgs. It is LGPL and can be used without KApplication if you really want (call KCmdLineArgs::init).
KCmdLineOptions options;
options.add("enable-foo", ki18n("enables foo"));
options.add("nodisable-foo", ki18n("disables foo"));
// double negatives are confusing, but this makes disable-foo enabled by default
KCmdLineArgs::addCmdLineOptions(options);
KApplication app;
KCmdLineArgs *args = KCmdLineArgs::parsedArgs();
if (args->isSet("enable-foo") && !args->isSet("disable-foo"))
cout << "foo enabled" << endl;
else
cout << "foo disabled" << endl;
Untested (who ever tests what they post on S.O.?).
Since Qt 5.2 you can finally find a solution in QtCore itself: I contributed QCommandLineParser there.
This is more or less the same answer as ephemient, but with a simple regexp to help parse the args. (This way could be useful if you only need a handful of args)
Run with this:
./QArgTest --pid=45 --enable-foo
And the code:
int main(int argc, char *argv[]) {
QApplication app(argc, argv, false);
qDebug() << "QApp arg test app";
QStringList args = app.arguments();
int pid = 0;
QRegExp rxArgPid("--pid=([0-9]{1,})");
QRegExp rxArgFooEna("--enable-foo");
QRegExp rxArgFooDis("--disable-foo");
for (int i = 1; i < args.size(); ++i) {
if (rxArgPid.indexIn(args.at(i)) != -1 ) {
pid = rxArgPid.cap(1).toInt();
qDebug() << i << ":" << args.at(i) << rxArgPid.cap(1) << pid;
}
else if (rxArgFooEna.indexIn(args.at(i)) != -1 ) {
qDebug() << i << ":" << args.at(i) << "Enable Foo";
}
else if (rxArgFooDis.indexIn(args.at(i)) != -1 ) {
qDebug() << i << ":" << args.at(i) << "Disable Foo";
}
else {
qDebug() << "Uknown arg:" << args.at(i);
}
}
return 0;
}
There is also QxtCommandOptions from http://www.libqxt.org/
That package does support --disable-foo and --enable-foo via opts.addSwitch("disable-foo", &foo_disabled); and opts.addSwitch("enable-foo", &foo_enabled);. You need handle checking both, and dealing with someone specifying both (oops).
What I don't understand is how this has anything to do with QT4...
Look at this: http://code.google.com/p/qtargparser/
A really simple method is to scan "key=value" args,
put them in a table say zz.map: QString -> QVariant,
and get their values with zz.map.value( key, default ).
An example:
#include "ztest.h"
Ztest zz;
int main( int argc, char* argv[] )
{
zz.eqargs( ++ argv ); // scan test=2 x=str ... to zz.map
QString xx = zz.map.value( "xx", "" );
if( Zint( Size, 10 )) // a #def -> zz.map.value( "Size", 10 )
...
ztest.h is < 1 page, below; same for Python ~ 10 lines.
(Everybody has his/her favorite options parser;
this one's about the simplest.
Worth repeating: however you specify options, echo them to output files --
"every scientist I know has trouble keeping track
of what parameters they used last time they ran a script".)
To make QPoints etc work one of course needs a QString -> QPoint parser.
Anyone know offhand why this doesn't work (in Qt 4.4.3) ?
QPoint pt(0,0);
QDataStream s( "QPoint(1,2)" );
s >> pt;
qDebug() << "pt:" << pt; // QPoint(1364225897,1853106225) ??
Added 25nov --
// ztest.h: scan args x=2 s=str ... to a key -> string table
// usage:
// Ztest ztest;
// int main( int argc, char* argv[] )
// {
// QApplication app( argc, argv );
// ztest.eqargs( ++ argv ); // scan leading args name=value ...
// int x = Zint( x, 10 ); // arg x= or default 10
// qreal ff = Zreal( ff, 3.14 );
// QString s = Zstr( s, "default" );
// care: int misspelled = Zint( misspellled ) -- you lose
//version: 2009-06-09 jun denis
#ifndef ztest_h
#define ztest_h
#include <QHash>
#include <QString>
#include <QVariant>
#include <QRegExp>
//------------------------------------------------------------------------------
class Ztest {
public:
QHash< QString, QVariant > map;
int test; // arg test=num, if( ztest.test )
Ztest() : test( 0 ) {}
QVariant val( const QString& key, const QVariant& default_ = 0 )
{
return map.value( key, default_ );
}
void setval( const QString& key, const QVariant& val )
{
map[key] = val;
if( key == "test" || key == "Test" )
test = val.toInt();
}
//------------------------------------------------------------------------------
// ztest.eqargs( ++ argv ) scans test=2 x=3 ... -> ztest table
void eqargs( char** argv )
{
char** argv0 = argv;
char *arg;
QRegExp re( "(\\w+)=(.*)" ); // name= anything, but not ./file=name
for( ; (arg = *argv) && re.exactMatch( arg ); argv ++ ){
setval( re.cap(1), re.cap(2) );
}
// change argv[0..] -> args after all name=values
while(( *argv0++ = *argv++) != 0 ) {}
}
};
extern Ztest ztest;
// macros: int x = Zint( x, 10 ): x= arg or default 10
#define Zstr( key, default ) ztest.val( #key, default ).toString()
#define Zint( key, default ) ztest.val( #key, default ).toInt()
#define Zreal( key, default ) ztest.val( #key, default ).toDouble()
#endif
It's 2013 and still no "1st party" arg parser. Anyways..if anyone finds themselves facing the same problem and would like to avoid the learning curves that come with cmd parser libs, here is a "quick & dirty" fix for you:-
QString QArgByKey(QString key, QChar sep = QChar('\0') ) //prototype usually in separate header
QString QArgByKey(QString key, QChar sep )
{
bool sepd=sep!=QChar('\0');
int pos=sepd?qApp->arguments().indexOf(QRegExp('^'+key+sep+"\\S*")):qApp->arguments().indexOf(QRegExp(key));
return pos==-1?QString::null:
(sepd?qApp->arguments().at(pos).split(sep).at(1):(++pos<qApp->arguments().size()?qApp->arguments().at(pos):QString::null));
}
Example:-
user#box:~$ ./myApp firstKey=Value1 --secondKey Value2 thirdKey=val3.1,val3.2,val3.3 --enable-foo
Usage:
QString param1 = QArgByKey("firstkey",'='); // Returns `Value1` from first pair
QString param2 = QArgByKey("--secondkey"); // Returns `Value2` from second pair
QString param3-1 = QArgByKey("thirdkey",'=').split(',').at(0); // Returns `val3.1`
bool fooEnabled = qApp->arguments().contains("--enable-foo"); //To check for `--enable-foo`
Params can be passed in any order
Edit: Updates to this snippet will be found here
Does it have to be Qt4 specific? If not, GNU Getopt is really nice, although licensing may be a problem if you are not doing open source software.
Also for some fancy options parsing you can try gperf.
IBM has a nice tutorial on it.
Another option I ran across while looking to do this, too:
http://code.google.com/p/qgetopts/
I haven't used it though.