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I'm wondering if you can set or create a Variable or Objects name from text file.
example: text file("Iron Copper Steel")
read the file and create a new Variable or Object with the name "Iron" then continue reading and create a new object or variable named "Copper", etc.
No you cannot.
Object names/variable names are fixed before compiling the code.
You want to use an interpreted language
A variable is a data item, which needs to be stored in memory, and the name is mapped to that memory location. Each variable name must be given at compile time (except the temporaries, which have no name). If you want to give anything a name which you will use for some reason, you can create a class which can have a string for name and you can set it after reading the file. But this is totally different than the concept of variable name in C++.
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For example, I have my class employee. I want to keep record how many employees till date have worked for me. I can make static count variable and add 1 in my constructor. But whenever my temporary object will be created when we pass object in parameters or return object of our class it will add for them too.
Static class member is the right way to go. A few things to be careful about:
Make sure you overload all constructors. The ones you don't want to support you should explicitly delete.
Don't forget to decrement in destructor.
If this program of yours is multithreaded then use atomic_uint or provide locking mechanism of your own.
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I want to make a function that has one parameter (a string that contains the name of a variable in my program) and returns the value that the variable stores.
Unfortunately, C++ doesn't provide a simple mechanism for reflection (the idea that the program can, at runtime, look up variable names by value or the like). You may need to consider using an alternate approach.
For example, you could make a std::unordered_map whose keys represent certain values that you'd like to look up and whose values are populated with the items you'd like to look up.
Hope this helps!
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I want to pass values from qml to set function written in Qt cpp, the values that will be passed is of different data types, example int or string, I will be writing only one set function in cpp which will take this values and return Qstring or int or double.How can I write a code for this.
C++ does know of two types:
QVariant
QJSValue
which might be the value, that you passed... That depends on you.
Both of them have various methods to test for their content, and to convert to this.
See the linked documentations for this.
You may even store the passed value as the corresponding type, without the need of conversion (up to the time, you need it for calculations in C++) It depends on, what you will do with it, to find the right choice.
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After asking C++ Error linking in consumer file caused by static data field, I tried two different declarations for an instance of StateConservator:
StateConservator cs(*pContainer, pDoc->GetConfiguration());
and
StateConservator(*pContainer, pDoc->GetConfiguration());
The first did what I want, it only passes on the destructor only after the end of the scope. The second passes on the destructor in the own line of the declaration itself.
Is the compiler behaving correctly? If it is the correct behavior what is the way to declare an anonymous variable in that line?
You cannot have "unnamed" objects in C++. In the second case, the object is created and destroyed instantaneously because it is not associated with a name. The association with a name (e.g., variable) gives an object scope which controls its lifetime. By not naming an object, it's lifetime is bound to the statement. If it is given a name, then it is bound to the scope that the name is declared in.
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I have the following problem:
I have a configuration file that consists a description of fields , which I read it and then parse it. I want to move it into the code to compile it inside.
How would you do that as bug structure ??? or else ?
Thanks
I wouldn't move it into the code, I'd leave the configuration file as a configuration file.
If you really must do this, you can just embed the file as a string resource into the application and use that - that way you'd change only a minimal amount of existing code. The way you do this depends upon your platform.
If thats not feasible (for whatever reason) I'd set up a single configuration class / namespace to contain all the values.
It's not very clear what are you exactly asking.
If you are looking for on-the-fly code execution (like eval() function in some languages), then there is no such thing in C++. It's not an interpreted language which can be read and executed line-by-line, it needs to be compiled every time code changes. While it technically is possible to write self-changing code, it's probably not worth the effort.