Type Casting

C# Type Casting

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

Two ways to convert

1. Implicit - automatic, happens when converting a smaller type to a larger one (no data loss).
2. Explicit - manual, needed when converting a larger type to a smaller one (possible data loss).

Implicit casting (automatic)

The compiler converts automatically from smaller to larger types:

int myInt = 9;
double myDouble = myInt;   // Automatic: int -> double

Implicit conversions: char -> int -> long -> float -> double.

Explicit casting (manual)

Use parentheses with the target type. This is required when going from a larger type to a smaller one:

double myDouble = 9.78;
int myInt = (int) myDouble;   // Manual: double -> int

myInt becomes 9 - the decimal part is truncated (not rounded).

Conversion Methods

The .NET Convert class handles conversions between types:

int myInt = 10;
double myDouble = 5.25;
bool myBool = true;

Console.WriteLine(Convert.ToString(myInt));    // "10"
Console.WriteLine(Convert.ToDouble(myInt));    // 10
Console.WriteLine(Convert.ToInt32(myDouble));  // 5
Console.WriteLine(Convert.ToString(myBool));   // "True"

Parsing strings

Convert a string into a number with int.Parse or Convert.ToInt32:

string text = "42";
int number = int.Parse(text);

TL;DR

• Implicit casting is automatic (small -> large).
• Explicit casting uses (type) and may lose data.
• Convert.ToString, Convert.ToInt32, etc. convert between types.
• Use int.Parse to turn a string into a number.