Dimensional Data

In addition to many beneficial features of C++ 17, there are elementary string conversions introduced in that specification. The std::to_chars() and std::from_chars() are defined in header to do conversions between numeric values to strings or strings to numeric values without considering locale-specific conversions. In this post, we explain the std::to_chars() and std::from_chars() that come with C++17. What Are The Elementary String Conversions That Come With C++ 17 ? What is std::to_chars()? The std::to_chars() is defined in header and is used to convert numeric values into a character string within the given valid range. The std::to_chars() is designed to copy the numeric value into a string buffer, with a given specific format, with the only overhead of making sure that the buffer is big enough. You don’t need to consider locale-specific conversions. Here is the syntax of std::to_chars in C++ 17.   std::to_chars_result  to_chars( char* first, char* last, value, int base = 10 );   Here is a simple example.   std::string str= “abcdefgh”; const int ival = 10001000; const auto con = std::to_chars( str.data(), str.data() + str.size(), ival);   In floating point number conversions, std::chars_format types can be used (i.e. std::chars_format::fixed, std::chars_format::scientific, std::chars_format::general,…) What is std::from_chars()? The std::from_chars() is defined in the header and used to convert the string data in a given range to a value (string to int, string to float operations) if no string characters match the pattern or if the obtained value is not representable in a given type of value, then the value has remains unchanged. The std::from_chars() is a lightweight parser that does not need to create dynamic allocation, and you don’t need to consider locale-specific conversions. Here is the syntax of std::from_chars in C++ 17.   std::from_chars_result from_chars( const char* first, const char* last, &value, int base = 10 );   Here is a simple example.   std::string str= “10001000”; int vali; auto [ptr, ec] = std::from_chars(str.data(), str.data() + str.size(), vali);   Is there a full example to elementary string conversions that comes with C++ 17? Here is a full example about std::to_chars() and std::from_chars() in C++ 17. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38   #include #include #include   int main() { std::string str= “abcdefgh”;   // INT TO CHAR const int ival = 10001000; const auto con = std::to_chars( str.data(), str.data() + str.size(), ival);   std::cout

In C++ Builder 12, and modern C++ the std::variant is one of the powerful features that comes with C++17. The std::variant is a discriminated union that we can work with multiple data types. It represents a type-safe union and holds one of its types in definition. What is the class template std::variant in C++ 17? The std::variant is a class template defined in  header that represents a disjoint union (or discriminated union). A value of variant contains one of an A, a B, or a C at any one time. It can be used as a multi-type variable, for example, a variable can be a float, an int, or a string. Here is the template definition since C++17:   template class variant;   Here is a simple example that shows how we can use it.   std::variant myvar; myvar = 100; // int   To get value of a variant we can use std::get (std::variant), here is how we can use it:   std::variant myvar2; myvar2 = std::get(myvar);   std::variant has many useful methods and properties that can be used in modern C++, such as index, valueless_by_exception, emplace, swap, get_if, visit, variant_size, variant_size_v, variant_npos, monostate, std::hash, and operators ( =, ==, !=, , =, ) Is there a full example about the class template variant in C++ 17? Here is an example. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23   #include #include #include   int main() { std::variant myvar;   //myvar = true; // bool myvar = 100; // int     if ( std::holds_alternative(myvar) ) std::cout

The C++ 17 standard bring us a lot of useful methods, templates and algorithms. One of the great algorithms is std::sample defined in the header that samples at most n elements uniformly from a given range. In this post, we explain the std::sample algorithm and how we can use it with an mt19937 random generator. What is the std::sample algorithm in C++ 17 and beyond? The std::sample algorithm is defined in header that samples at most n elements uniformly from a given range into the output iterator and random numbers can be generated by using a random number generator function. Generally std::mt19937{} is used as random generator and std::random_device{}() is used random generator device. The std::sample algorithm is defined as a template algorithm in C++17 as shown below.   template SampleIterator sample( PopulationIterator first_in, PopulationIterator last_in,                        SampleIterator output, Distance n, URBG&& function );   Here, first_in and last_in are the iterators that defines range of input. n is number of elements to be sampled into output iterator, function is random number generator function. Is there a full example about the std::sample algorithm in C++ 17 and beyond? Here is a full example about std::sample in C++ 17. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28   #include #include #include #include #include #include   int main() { std::vector vec_in {“This”, “LearnCPlusPlus.org”, “is”, “really”, “amazing”,“!”}; std::vector vec_out;   std::cout

Classes and Objects are part of object-oriented methods and typically provide features such as properties and methods. One of the great features of an object orientated language like C++ is a copy assignment operator that is used with operator= to create a new object from an existing one. In this post, we explain what a copy assignment operator is and its types in usage with some C++ examples. What is a copy assignment operator in C++? The Copy Assignment Operator in a class is a non-template non-static member function that is declared with the operator=. When you create a class or a type that is copy assignable (that you can copy with the = operator symbol), it must have a public copy assignment operator. Here is a simple syntax for the typical declaration of a copy assignment operator which is defaulted: Syntax (Since C++11).   class_name & class_name :: operator= ( const class_name& ) = default;   Here is an example in a class.   Tmyclass& operator=(const Tmyclass& other) = default; // Copy Assignment Operator   Is there a simple example of using the copy assignment operator in C++? The forced copy assignment operator is default in any class declarations. This means you don’t need to declare it as above. Let’s give examples without using it. Let’s give a simple C++ example to copy assignment operator with default option, here is a simple class:   class myclass {   public:   std::string str;   };   Because this is default in any class declaration, and it is automatically declared. This class is same as below.   class myclass {   public:   std::string str;     Tmyclass& operator=(const Tmyclass& other) = default; // Copy Assignment Operator };   And here is how you can use this “=” copy assignment operator with both class examples above.   Tmyclass o1, o2;   o2 = o1; // Using Copy Assignment Operator   now let’s see different usage types in C++, 1. Typical Declaration of A Copy Assignment Operator with Swap 2. Typical Declaration of A Copy Assignment Operator ( No Swap) 3. Forced Copy Assignment Operator 4. Avoiding Implicit Copy Assignment 5. Implicitly-declared copy assignment operator 6. Deleted implicitly declared copy assignment operator 7. Trivial copy assignment operator 8. Eligible copy assignment operator 9. Implicitly-defined copy assignment operator C++ Builder is the easiest and fastest C and C++ compiler and IDE for building simple or professional applications on the Windows operating system. It is also easy for beginners to learn with its wide range of samples, tutorials, help files, and LSP support for code. RAD Studio’s C++ Builder version comes with the award-winning VCL framework for high-performance native Windows apps and the powerful FireMonkey (FMX) framework for UIs. There is a free C++ Builder Community Edition for students, beginners, and startups; it can be downloaded from here. For professional developers, there are Professional, Architect, or Enterprise versions of C++ Builder and there is a trial version you can download from here.

The C++17 standard came with a lot of great features and std::optional was one of the main features of today’s modern C++. std::optional is a class template that is defined in the header and represents either a T value or no value. In this post, we explain, what is optional in modern C++ and how we can use it efficiently. What is the optional class template in C++ 17 and beyond? The std::optional feature is a class template that is defined in the header and represents either a T value or no value (which is signified by the tag type nullopt_t). In some respects, this can be thought of as equivalent to variant, but with a purpose-built interface. Here is the definition of the std::optional class template.   template class optional;   Optional can be used to define any type of variables as below.   std::optional a(5); std::optional b;   An optional variable can be checked by has_value() method if it has a value or not.   if (a.has_value()) { }   Here is another example that has a function with an optional return.   std::optional testopt(std::string s) { if(s.length()==0) return {}; else return s; }   as you see our function may return a string as an option or it may have no return value. A common use case for optional is the return value of a function that may fail. Any instance of optional at any given point in time either contains a value or does not contain a value. If an optionalcontains a value, the value is guaranteed to be allocated as part of the optional object footprint, i.e. no dynamic memory allocation ever takes place. Thus, an optional object models an object, not a pointer, even though operator*() and operator->() are defined. Is there a simple example about the optional class template in C++ 17? Here is a simple example about the std::optional, 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19   #include #include   int main() { std::optional a(5);  // a = 5 std::optional b;   // b has no value   if (a.has_value())         { int z = a.value() + b.value_or(0); std::cout

C++17 had enormous changes in C++ features. One of them was basic_string_view (std::basic_string_view) which is a constant string container that can be used for multiple string declarations. The basic_string_view is a modern way of read-only text definition. It can be used by iterators and other methods of the basic_string_view class. In this post, we explain basic_string_view and its types. What is basic_string_view in modern C++ In the Library Fundamentals Technical Specification (LFTS), The C++ commitee introduced std::basic_string_view, and it was approved for C++17. The basic_string_view (std::basic_string_view) is a class template defined in the header that is used to define a constant string container that can be used to define multiple strings which refers to the contiguous character sequence, and the first element of this sequence position at the zero position. The basic_string_view is a modern way of read-only text definition, it can be used by iterators, and other methods of the basic_string_view class can be used.  Here is the syntax of the basic_string_view:   template class basic_string_view;   We can use different character types in std::basic_string_view types as same as std::basic_string. The std::basic_string_view has 5 different string types, these are, std::string_view, std::wstring_view, std::u8string_view, std::u16string_view, and std::u32string_view. The std::string_view provides read-only access to a string definition with chars as similar to the interface of std::string. In addition to this, we can use std::wstring_view, std::u16string_view, and std::u32string_view in C++17. There is std::u8string_view that is added by the C++20 standards too. Here are the basic_string_types and their features. Type Char Type Definition Standard std::string_view char std::basic_string_view (C++17) std::wstring_view wchar_t std::basic_string_view (C++17) std::u8string_view char8_t std::basic_string_view (C++20) std::u16string_view char16_t std::basic_string_view (C++17) std::u32string_view char32_t std::basic_string_view (C++17) Is there an example about basic_string_view in modern C++ Here is a C++ example that we use std::string_view, std::wsting_view, std::u16string_view, std::u32string_view in C++17. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30   #include #include #include   int main() { const std::string_view  sview = “This is a stringview example”; const std::wstring_view wsview = L“This is a stringview example”; const std::u16string_view u16sview = u“This is a stringview example”; const std::u32string_view u32sview = U“This is a stringview example”;   const std::string_view sviews[]{ “This is “, “LearnCPlusPlus.org “, “and welcome “, “!” };   for ( auto sv : sviews) { std::cout