Generic function in c++ with example






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So if you want to maximize your code resuability and maintain its type safety, and performance then use generics. You can implement the first as a macro: define incr x ++ x Of course, this can have unpleasant side effects if you're not careful. If the return type is void, no return value is required. Generic class and Generic methods follow the same constraints.
T must be inherit from U. There could be a virtually infinite number of specializations of generic functions or types. In Visual C++, class or struct constructors may not be declared with generic type parameters. Generics enable you to work with typesafe data with no boxing and unboxing overhead.
Remarks Generic custodes generic function in c++ with example functions declared with a generic type parameter. Behind the scenes, languages that build in polymorphism are doing something just like this behind the scenes. The compiler applies type inference logic to all generic methods that share the same name. For example, the following methods can all be met in the same class: void DoWork   void DoWork   void DoWork   C Language Specification For more information, see the. Otherwise, you're probably in for weird behavior. The length of the block of memory isn't even stored in the pointer, let alone the xi of the data. Since it does both sort and swap, let's look at qsort in a little more detail. In the main method, we have passed the type argument in the Helper class. Generics replace these placeholders with some specific type at compile time. Piece public class GenericsClass {. At that moment, when an instantiation is required, the compiler generates a function specifically for those arguments from the template. You can leverage generics to create typesafe collections, as well as classes and methods that can accept a type as a parameter. 
C# Generic Methods - It's about the only method C provides for applying the same operation to any of a variety of types though. You can't do exactly what you're asking - operators like increment need to work with a specific type.
I have an incr function to increment the value by 1 I want to make it generic,because I don't want to make different functions for the same functionality. Sometimes It may give error : Invalid use of void expression. Is there a way to solve it in Conly or will I have to define incr for each datatypes? I want to swap and sort all kinds of data types with same function. You can implement the first as a macro: define incr x ++ x Of course, this can have unpleasant side effects if you're not careful. It's about the only method C provides for applying the same operation to any of a variety of types though. In particular, since the macro is implemented using text substitution, by the time the compiler sees it, you just have the literal code ++whatever;, and it can apply ++ properly for the type of item you've provided. With a pointer to void, you don't know much if anything about the actual type, so you can't do much direct manipulation on that data. In some cases e. Since it does both sort and swap, let's look at qsort in a little more detail. The second tells qsort the number of elements in the array. The third, the size of each element in the array. The last is a pointer to a function that can compare individual items, so qsort doesn't need to know how to do that. To achieve actual polymorphic behavior, you will have to pass in the type information as another variable and check for it in your incr function, then casting the pointer to the desired type OR by passing in any operations on your data as function pointers others have mentioned qsort as an example. C does not have automatic polymorphism built in to the language, so it would be on you to simulate it. Behind the scenes, languages that build in polymorphism are doing something just like this behind the scenes. The length of the block of memory isn't even stored in the pointer, let alone the type of the data. Remember that internally, all data are bits and bytes, and types are really just markers for how the logical data are physically encoded, because intrinsically, bits and bytes are typeless. In C, this information is not stored with variables, so you have to provide it to the compiler yourself, so that it knows whether to apply operations to treat the bit sequences as 2's complement integers, IEEE 754 double-precision floating point, ASCII character data, functions, etc. Otherwise, you're probably in for weird behavior. It's good for dealing with blocks of data without regards to type. This is necessary for things like memory allocation, copying, file operations, and passing pointers-to-functions. In almost all cases though, a C programmer abstracts from this low-level representation as much as possible by structuring their data with types, which have built-in operations; or using structs, with operations on these structs defined by the programmer as functions. You may want to for more info. You can't do exactly what you're asking - operators like increment need to work with a specific type. Both your swap and sort functions fall into this category. This code swaps two blocks of memory. I know that kind of dodged the original question; but hopefully it still solves your original problems. You can use the type-generic facilities C11 standard. If you intend to use more advanced math functions more advanced than the ++ operator , you can go to , which is type-generic definitions of the functions in and.