Cpp - Auto-Typed Variables

Introduction

The auto keyword makes C++ to infer type based on the value initially assigned to it.

The literal assigned to the variable at initialization determines the type.

The compiler figures out a suitable data type. Here are some examples:

auto index = 3; 
auto multiple = 2.25F; 
auto rate = 500 / 3.0; 

These statements create an index variable that holds an int value, a multiple variable that holds a float and a rate variable that holds a double.

In the preceding example is the same as follows:

int index = 3; 
float multiple = 2.25F; 
double rate = 500 / 3.0; 

When using auto, you must assign the variable a value at initialization.

Multiple variables can be assigned with an auto keyword as long as every one of the variables has the same data type.

auto a = 86, b = 75, c = 309; 

The following code shows how to use auto to define variables.

Demo

#include <iostream> 
 
int main() // w  w  w .  j  a  v  a2  s .co  m
{ 
    // define character values 
    auto strength = 80; 
    auto accuracy = 45.5; 
    auto dexterity = 24.0; 
 
    // define constants 
    const auto MAXIMUM = 50; 
 
    // calculate character combat stats 
    auto attack = strength * (accuracy / MAXIMUM); 
    auto damage = strength * (dexterity / MAXIMUM); 
 
    std::cout << "\nAttack rating: " << attack << "\n"; 
    std::cout << "Damage rating: " << damage << "\n"; 
}

Result