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Type Inference in C++ (auto and decltype)
In this tutorial, we will be discussing a program to understand Type interference in C++ (auto and decltype).
In case of auto keyword, the type of the variable is defined from the type of its initializer. Further with decltype, it lets you extract the type of variable from the called element.
auto type
Example
#include <bits/stdc++.h>
using namespace std;
int main(){
auto x = 4;
auto y = 3.37;
auto ptr = &x;
cout << typeid(x).name() << endl
<< typeid(y).name() << endl
<< typeid(ptr).name() << endl;
return 0;
}Output
i d Pi
decl type
Example
#include <bits/stdc++.h>
using namespace std;
int fun1() { return 10; }
char fun2() { return 'g'; }
int main(){
decltype(fun1()) x;
decltype(fun2()) y;
cout << typeid(x).name() << endl;
cout << typeid(y).name() << endl;
return 0;
}Output
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Updated on: 12-Mar-2020
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