Type Casting

In C++, converting a value from one data type to another is called type casting (or type conversion). This is necessary when you need to perform operations involving different data types or to ensure an operation, like division, behaves exactly as you intend.

Implicit Type Casting

This is when the C++ compiler automatically converts one data type to another without you explicitly telling it to. This usually happens when a value of one type is assigned to a variable of another type, or in expressions with mixed types. The compiler generally allows conversions that it considers "safe."

#include <bits/stdc++.h>
using namespace std;

int main() {
    // Promotion: int to double (safe)
    int x = 5;
    double y = x; // y is now 5.0
    cout << "y = " << y << endl;

    // Promotion: char to int (safe)
    char c = 'A';
    int i = c; // i is now 65 (the ASCII value of 'A')
    cout << "i = " << i << endl;

    // Demotion: double to int (potential data loss!)
    double pi = 3.14159;
    int truncated_pi = pi; // truncated_pi is now 3 (the decimal part is lost)
    cout << "truncated_pi = " << truncated_pi << endl;
}

Explicit Type Casting

This is when you, the programmer, explicitly force a type conversion. This is often needed to get the desired behavior from an operation. The most commonly used syntax to do this is (new_type)value.

#include <bits/stdc++.h>
using namespace std;

int main() {
    // Promotion: int to double
    int x = 5;
    cout << "x = " << (double)x << endl; // Output: 5.0

    // Promotion: char to int
    char c = 'A';
    cout << "c = " << (int)c << endl; // Output: 65 (the ASCII value of 'A')

    // Demotion: double to int (potential data loss!)
    double pi = 3.14159;
    cout << "pi = " << (int)pi << endl;
    // Output: 3 (the decimal part is lost)
}