Apprendre Conversion de Types de Base | Gestion des Types de Données

Type Casting is the process of converting a value from one data type to another. This is often possible between types that represent numbers. For example, you can convert a float to an int and vice versa. However, converting a string directly to an int doesn't make logical sense and is not possible without additional steps.

There are two types of type casting: implicit type casting and explicit type casting.

Implicit type casting occurs automatically when a value is converted from one type to another, usually from a smaller to a larger data type.

main.cs


              1234
            
int val1 = 10;
long val2 = val1; // int is automatically converted to long
float val3 = var1; // int is automatically converted to float
double var4 = var1; // int is automatically converted to double

Implicit type casting happens automatically when a smaller data type is converted to a larger one. The size of a data type is determined by how much data it can hold, measured in bits. For example, an int can hold 32 bits, while a long can hold 64 bits, so converting an int to a long happens automatically. Similarly, a float can be converted to a double without any issues.

Here's a list of data types ordered from smallest to largest: char -> int -> long -> float -> double

Explicit type casting is when you, as the programmer, tell the computer to convert a value to a different data type. This is necessary when converting from a larger data type to a smaller one because some data might be lost. For example, converting the float 3.14 to an integer results in 3, losing the decimal part. That's why you need to explicitly tell the computer to make such conversions.

main.cs


              123456789101112131415
            
using System;

namespace ConsoleApp
{
    internal class Program
    {
        static void Main(string[] args)
        {
			float val1 = 3.14f;
			int val2 = val1; // Error: Cannot implicitly convert type 'float' to 'int'. An explicit conversion exists (are you missing a cast?)
			Console.WriteLine(val1);
			Console.WriteLine(val2);
        }
    }
}

To fix the error in the above code, we need to explicitly cast val1 to an integer value.

The syntax of a cast is (datatype) value, for-example (int) 3.1415. So in this case we will write (int) val1:

main.cs


              123456789101112131415
            
using System;

namespace ConsoleApp
{
    internal class Program
    {
        static void Main(string[] args)
        {
			float val1 = 3.14f;
			int val2 = (int) val1;
			Console.WriteLine(val1);
			Console.WriteLine(val2); 
        }
    }
}

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Section 2. Chapitre 11

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There are two types of type casting: implicit type casting and explicit type casting.

Implicit type casting occurs automatically when a value is converted from one type to another, usually from a smaller to a larger data type.

main.cs


              1234
            
int val1 = 10;
long val2 = val1; // int is automatically converted to long
float val3 = var1; // int is automatically converted to float
double var4 = var1; // int is automatically converted to double

Here's a list of data types ordered from smallest to largest: char -> int -> long -> float -> double

main.cs


              123456789101112131415
            
using System;

namespace ConsoleApp
{
    internal class Program
    {
        static void Main(string[] args)
        {
			float val1 = 3.14f;
			int val2 = val1; // Error: Cannot implicitly convert type 'float' to 'int'. An explicit conversion exists (are you missing a cast?)
			Console.WriteLine(val1);
			Console.WriteLine(val2);
        }
    }
}

To fix the error in the above code, we need to explicitly cast val1 to an integer value.

The syntax of a cast is (datatype) value, for-example (int) 3.1415. So in this case we will write (int) val1:

main.cs


              123456789101112131415
            
using System;

namespace ConsoleApp
{
    internal class Program
    {
        static void Main(string[] args)
        {
			float val1 = 3.14f;
			int val2 = (int) val1;
			Console.WriteLine(val1);
			Console.WriteLine(val2); 
        }
    }
}

Tout était clair ?

Merci pour vos commentaires !

Section 2. Chapitre 11