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this we pass data types as parameter so we don’t need to write codes

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<h3 class="pb-3 pt-3">Templates in C++</h3>

<p>In this tutorial, we are going to learn about C++ templates.</p>

<p>A template is a simple and powerful tool in C++ programming. Using

this we pass data types as parameter so we don’t need to write codes

again and again.</p>

<p>One of the best real life example of templates are <strong>forms</strong>. Forms may be

of various kinds like bank form, admission form, account opening form

etc. but the main aim of a form is to make data more generalized and

accessible.</p>

<p>Templates are often used in larger codebase for the purpose of code

reusability and flexibility of the programs.</p>

<p>The concept of templates can be used in two different ways:</p>

<ul>

<li>Function Templates</li>

<li>Class Templates</li>

</ul>

<hr/>

<h4 class="pt-3 pb-3">Function templates</h4>

<p>look at the following program</p>

<pre>#include <iostream>

using namespace std;

int greater(int a,int b){ // first function

if(a>b)

return a;

else

return b;

}

double greater(double a,double b){

if(a>b) // second funtion

return a;

else

return b;

}

int main(){

cout<< greater(5,4); //first function call

cout<< greater(4.5,6.7); //second function call

return 0;

}</pre>

<p>As you can see in the above program, we want to pass values of two

different data types. But for this we need to create two functions, have

change only in data type of argument.

</p>

<p>This can be resolved by making function templates.</p>

<p>The syntax of function template is given below:</p>

<pre>template<class type> type funcName(type arg1,….);</pre>

<p>the syntax consists keyword <strong>template</strong> followed by angular brackets

containing a keyword <strong>class</strong> and a variable datatype <strong>type</strong>. you can

represent type by any name and letter just as a variable. After <strong>type</strong> in

angular bracket, there is one more <strong>type</strong> followed by function name and

parameters.</p>

<p>Look at the following example</p>

<p><strong>Example:</strong></p>

<pre>#include<iostream>

using namespace std;

template <class X> X greater(X a,X b){ //function template

if(a>b)

return a;

else

return b;

}

int main(){

cout<< greater(5,4);

cout<< greater(4.5,6.7);

return 0;

}</pre>

<p>in the above program, we have <strong>X</strong> as <strong>type</strong> according to the syntax. Here

<strong>X</strong> is acting as variable data type, which depends upon the type of value

passed in the argument of the function.

</p>

<p>For example, when <strong>5</strong> and <strong>4</strong> were passed in the argument, <strong>X</strong> was acting

as int datatype. And when <strong>4.5</strong> and <strong>6.7</strong> were passed, <strong>X</strong> was acting as

double.</p>

<hr/>

<h4 class="pt-3 pb-3">Class templates</h4>

<p>Class template is also known as generic class</p>

<p>The syntax of class template is given below.</p>

<pre>template<typename type> class className{….};</pre>

<p>like functions, classes also requires parameters for their member

functions. Thus they also need to have a general datatype, which

change according to value passed. Hence we need class templates to

make it possible.</p>

<p>Go through the following example for better understanding.</p>

<p><strong>Example:</strong></p>

<pre>#include<iostream>

using namespace std;

template <typename T> //class template

class height{

T feet;

public:

void setData(T x)

{

feet=x

}

T getData(){

return feet;

}

};

int main(){

height <int>h1;

h1.setData(5);

cout<<"height is : "<< h1.getData<< endl;

height <double>h2;

height h2;

h2.setData(5.3);

cout<<"height is : "<< h2.getData()<< endl;

return 0;

}</pre>

<p><strong>Output:</strong></p>

<pre>height is : 5

height is : 5.3</pre>

<p>in the above program, as you can see we need to pass values to a

member function <strong>setData()</strong>.</p>

<p>Hence we declared class <strong>height</strong> as class template as</p>

<pre>template <typename T>

class height{…};</pre>

<p>here we passed int value to the member function by declaring object

as</p>

<pre>height <int>h1; </pre>

<p>similarly, passed double value to the same member function by

declaring object as</p>

<pre>height <double>h2;</pre>

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