Type Casting in C++

Learn type casting in C++ with simple explanations and examples. Understand implicit and explicit casting, conversion between int and float, and how C++ handles data type conversion in programs.

1. What is Type Casting?

Type casting means converting a value from one data type to another data type.

For example:

int x = 10;
double y = x;

Here, int is converted to double.

int → double

2. Types of Type Casting

There are two basic types:

1. Implicit Type Casting
2. Explicit Type Casting

3. Implicit Type Casting

Implicit casting happens automatically.

The compiler performs the conversion without being told.

Example

int x = 10;
double y = x;

cout << y;

Output

10

Here:

int → double

The compiler automatically converts 10 into 10.0.

Remember

Implicit = Automatic

4. Explicit Type Casting

Explicit casting is done by the programmer.

The programmer tells C++ which data type to convert the value into.

Example

double x = 10.75;
int y = (int)x;

cout << y;

Output

10

Here:

double → int

The decimal part .75 is removed.

Remember

Explicit = Programmer tells C++

5. Another Example

int a = 5;
int b = 2;

double result = (double)a / b;

cout << result;

Output

2.5

The programmer explicitly converts a:

int → double

So the calculation becomes:

5.0 / 2 = 2.5

6. Implicit vs Explicit Casting

7. Exmaples

Example 1: Implicit Casting — int to double

#include <iostream>
using namespace std;

int main() {
    int num = 10;
    double result = num;

    cout << result;

    return 0;
}

Output:

10

Understand the Code:

• num is an int.
• result is a double.
• C++ automatically converts int to double.
• This is implicit casting.

Example 2: Explicit Casting — double to int

#include <iostream>
using namespace std;

int main() {
    double num = 15.75;
    int result = (int)num;

    cout << result;

    return 0;
}

Output:

15

Understand the Code:

• num contains 15.75.
• (int)num converts it to an integer.
• The decimal part .75 is removed.
• This is explicit casting.

Example 3: Explicit Casting in Division

#include <iostream>
using namespace std;

int main() {
    int a = 5;
    int b = 2;

    double result = (double)a / b;

    cout << result;

    return 0;
}

Output:

2.5

Understand the Code:

• Normally, 5 / 2 gives 2 because both values are integers.
• (double)a converts 5 into 5.0.
• Now the calculation becomes 5.0 / 2.
• The result is 2.5.

⭐ Remember

Implicit casting: C++ does it automatically.

Explicit casting: The programmer does it using:

(type)value

Example:

(double)a
(int)num