#ifndef NEBULA_PLATFORM_CORE_TYPES_HPP
#define NEBULA_PLATFORM_CORE_TYPES_HPP

#include<type_traits>
#include<utility>
#include<optional>
#include<variant>

namespace nebula {
namespace platform {
namespace core {

enum class StdRetVals {

};

template<typename T, typename E = StdRetVals>
class Result final {
public:
    using valueType = T;
    using errorType = E;

    template<typename... Args, typename = std::enable_if<std::is_constructible<T, Args&&...>::value>>
    static Result FromValue(Args&&... args) {
        return Result{std::in_place_type<T>, std::forward<Args>(args)...};
    }

    static Result FromValue(T const& t) {
        return Result{std::in_place_type<T>, t};    
    }
    
    static Result FromError(E err) {
        return Result{std::in_place_type<E>};
    }

    template<typename... Args>
    Result(std::in_place_type_t<T>, Args&&... args) : dataVal{std::in_place_type<T>, std::forward(args)... } {

    }

    template<typename... Args>
    Result(std::in_place_type_t<E>, Args&&... args) : dataVal{std::in_place_type<E>, std::forward(args)... } {

    }

    Result(T const& t) : Result{std::in_place_type<T>, t} {

    }

    Result(T&& t) : Result{std::in_place_type<T>, std::move(t)} {

    }

    Result(E const& e) : Result{std::in_place_type<E>, e} {

    }

    Result(E&& e) : Result{std::in_place_type<E>, std::move(e)} {

    }

private:
    std::variant<T,E> dataVal;
};

}
}
}

int main() {
    auto k = nebula::platform::core::Result<int>::FromValue(10);
}

#endif

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Read inputs from stdin

OneCompiler's C++ online compiler supports stdin and users can give inputs to programs using the STDIN textbox under the I/O tab. Following is a sample program which takes name as input and print your name with hello.

#include <iostream>
#include <string>
using namespace std;

int main() 
{
    string name;
    cout << "Enter name:";
    getline (cin, name);
    cout << "Hello " << name;
    return 0;
}

About C++

C++ is a widely used middle-level programming language.

  • Supports different platforms like Windows, various Linux flavours, MacOS etc
  • C++ supports OOPS concepts like Inheritance, Polymorphism, Encapsulation and Abstraction.
  • Case-sensitive
  • C++ is a compiler based language
  • C++ supports structured programming language
  • C++ provides alot of inbuilt functions and also supports dynamic memory allocation.
  • Like C, C++ also allows you to play with memory using Pointers.

Syntax help

Loops

1. If-Else:

When ever you want to perform a set of operations based on a condition If-Else is used.

if(conditional-expression) {
   //code
}
else {
   //code
}

You can also use if-else for nested Ifs and If-Else-If ladder when multiple conditions are to be performed on a single variable.

2. Switch:

Switch is an alternative to If-Else-If ladder.

switch(conditional-expression){    
case value1:    
 // code    
 break;  // optional  
case value2:    
 // code    
 break;  // optional  
......    
    
default:     
 code to be executed when all the above cases are not matched;    
}

3. For:

For loop is used to iterate a set of statements based on a condition.

for(Initialization; Condition; Increment/decrement){  
  //code  
}

4. While:

While is also used to iterate a set of statements based on a condition. Usually while is preferred when number of iterations are not known in advance.

while (condition) {  
// code 
}

5. Do-While:

Do-while is also used to iterate a set of statements based on a condition. It is mostly used when you need to execute the statements atleast once.

do {  
 // code 
} while (condition);

Functions

Function is a sub-routine which contains set of statements. Usually functions are written when multiple calls are required to same set of statements which increases re-usuability and modularity. Function gets run only when it is called.

How to declare a Function:

return_type function_name(parameters);

How to call a Function:

function_name (parameters)

How to define a Function:

return_type function_name(parameters) {  
 // code
}