C + + templates (Templates)

Templates are the basis of generic programming , and the meaning of " generics " is that no specific data types are not dependent. The introduction of templates is to create generic classes (template classes) or functions (template functions). Typical containers such as iterators/algorithms are typical examples of generic programming. For example, define a vector that can use Vector<int>, Vector<string>, vector<vector>, and so on.

function templates

The general definition of a template function is: The type here can be seen as a placeholder name representing a data type, which can be used within the definition of a function.

Template <class
Ret-type func-Name (parameter list) {      //  body of function}

Examples are analyzed below. Note that the typename keyword and class keyword function is the same , the class keyword will let you produce whether the definition of the type can only be a class, but not other data types? To avoid this ambiguity, TypeName is introduced here!!!

1#include <iostream>2#include <string>3 4 using namespacestd;5 6Template <TypeNameT>7Inline TConst& Max (TConst& A, TConst&b) {8     returnA < b?b:a;9 }Ten  One intMain () { A  -     inti = the; -     intj = -; thecout <<"Max (i, J)"<< Max (i, J) <<Endl; # Max (i,j): -  -     DoubleF1 =13.5; -     DoubleF2 =20.7; +cout <<"Max (F1, F2)"<< Max (F1, F2) <<Endl; # Max (F1, F2): 20.7 -  +     stringS1 ="Hello"; A     stringS2 =" World"; atcout <<"Max (S1, S2)"<< Max (S1, S2) <<Endl; # Max (S1, S2): World -  -     return 0; -  -}

Class template

Just as we define a function template, you can define a class template here as well. The general form of declaring a class template is:

Template <class type>classclass-name{  }

Example:

#include <iostream>#include<vector>#include<cstdlib>#include<string>#include<stdexcept>using namespacestd;template<classT>classStack {Private: Vector<T> Elems;//Elements    Public:       voidPush (TConst&);//Push Element      voidPop ();//Pop elementT Top ()Const;//Return Top element      BOOLEmpty ()Const{//return True if empty.         returnElems.empty (); } }; Template<classT>voidStack<t>::p Ush (TConst&elem) {    //append copy of passed elementElems.push_back (Elem); } template<classT>voidStack<t>::p op () {if(Elems.empty ()) {ThrowOut_of_range ("Stack<>::p op (): Empty Stack"); }       //Remove last elementElems.pop_back (); } template<classT>T Stack<t>::top ()Const {    if(Elems.empty ()) {ThrowOut_of_range ("stack<>::top (): Empty Stack"); }       //return copy of last element   returnElems.back (); } intMain () {Try{Stack<int> intstack;//Stack of INTsstack<string> stringstack;//Stack of Strings//manipulate int StackIntstack.push (7); cout<< intstack.top () <<Endl; //7 //Manipulate string StackStringstack.push ("Hello"); cout<< stringstack.top () <<Std::endl;       //Hello stringstack.pop ();    Stringstack.pop (); }Catch(ExceptionConst&ex) {Cerr<<"Exception:"<< ex.what () <<Endl; //Exception:stack<>::p op (): Empty Stack return-1; } } 

Reference:

[1] C + + templates:https://www.tutorialspoint.com/cplusplus/cpp_templates.htm

C + + templates (Templates)