Array class const int.MaxValue int.Parse namespace Nullable Odd, Even short

`Int`

In computer programs, a larger, standard type (like int and uint) is easier to access than a smaller one (like a bit). In C# int has advantages: it has optimized performance.

Used in loops, for local variables and class fields, and returned from methods, the C# int is everywhere. Int is 4 bytes, while nint is a native-sized int.

`Int` example

Here we use ints in a variety of ways, and also test their physical characteristics (memory usage). We use Console.WriteLine to write the integer to the screen.

Part 1 We declare and assign an int. It will be placed into a local variable slot in the stack memory.

Part 2 You can compare 2 integers (variables or values) using the "==" equality operator. This compares all the bits for equivalence.

Part 3 The int type also has MinValue and MaxValue properties. These are useful for when you want to loop through all integers.

Part 4 This part of the program shows that each integer, when allocated as part of an array, will occupy 4 bytes.

using System;

// Part 1: demonstrate an int value type.
int number = 11;
Console.WriteLine(number);
number = -1; // Can be negative
Console.WriteLine(number);

// Part 2: use operators.
Console.WriteLine(number == -1);
Console.WriteLine(number + 100);
Console.WriteLine(number.GetType());
Console.WriteLine(typeof(int));

// Part 3: get minimum and maximum.
Console.WriteLine(int.MinValue);
Console.WriteLine(int.MaxValue);

// Part 4: find the memory usage for an int in an array.
long bytes1 = GC.GetTotalMemory(false);
int[] array = new int[1000 * 1000];
array[0] = 1;
long bytes2 = GC.GetTotalMemory(false);
Console.WriteLine(((bytes2 - bytes1) / (1000 * 1000)).ToString("0 bytes per int"));11
-1
True
99
System.Int32
System.Int32
-2147483648
2147483647
4 bytes per int

Minimum, maximum

Here we consider both Int32 and UInt32, the unsigned int type. With int we can go negative, but with uint we have a higher maximum.

int.MinValue = -2147483648
int.MaxValue =  2147483647uint.MinValue = 0
uint.MaxValue = 4294967295

`Int` arguments

We use int as a parameter. You can pass a variable or a constant to the method that uses an integer parameter. An int argument is a common type.

Info The arguments are copied to the new method whenever it is called, but this cost is reduced when functions are inlined.

Here The program shows the boolean method pattern. This can help simplify complex tests.

using System;

// Use integer type as argument to method.
bool result = IsOdd(1);
Console.WriteLine(result);

// Test call the method with different integers.
result = IsOdd(6);
Console.WriteLine(result);

result = IsOdd(100);
Console.WriteLine(result);

result = IsOdd(101);
Console.WriteLine(result);

// Use the integer parameter in the method body.
static bool IsOdd(int number) => number % 2 != 0;True
False
False
True

Uint example

Uint is similar to int, but reserves no space for the sign. Unsigned integers can be used through many programs. With uint we can increase the bounds of a loop.

Detail The uint type is the same as the System.UInt32 type in the System namespace. This alias provides for clearer code in programs.

Tip When code that uses uint is executed, it is allocated in the method's stack. No dynamic heap allocation is done. This is efficient.

Result The program displays the System.Type object for the 2 numeric types. This shows the struct that uint aliases to.

Info Uints lack the sign bit that, when set, makes a number equal a negative value.

using System;

// Declare example unsigned and signed integers.
uint value1 = 100;
int value2 = 100;

// Display values.
Console.WriteLine(value1);
Console.WriteLine(value2);

// Assign the maximum values.
uint max1 = uint.MaxValue;
int max2 = int.MaxValue;

// Display maximum values.
Console.WriteLine(max1);
Console.WriteLine(max2);

// Assign the minimum values.
uint min1 = uint.MinValue;
int min2 = int.MinValue;

// Write the minimum values.
Console.WriteLine(min1);
Console.WriteLine(min2);

// Write the types.
Console.WriteLine(typeof(uint));
Console.WriteLine(typeof(int));100
100
4294967295
2147483647
0
-2147483648
System.UInt32
System.Int32

`Int` errors

If you try to assign an int variable in your program to a numeric literal that is too big, the C# compiler will give you a compile-time error.

So For example, try compiling code that assigns an int to 3000000000. The C# compiler will give the error here.

Tip If you change the "int" type to "uint," your program will compile successfully.

class Program
{
    static void Main()
    {
        int value1 = 3000000000;
    }
}Error CS0266
Cannot implicitly convert type 'uint' to 'int'.
An explicit conversion exists (are you missing a cast?)

Null `int`

An int can never be null. But we can use a nullable int, which is a struct that wraps around an int value, to represent a null int.

Info A nullable int can be tested directly against null. This makes it different from a class instance that has an int field.

using System;

// A nullable int can be a number, or null.
int? test = 100;
Console.WriteLine("Value is {0}", test.Value);
test = null;
Console.WriteLine("Null: {0}", test == null);Value is 100
Null: True

Nint, nuint

In C# there is also the concept of a "native" int. This is the size of integers used in C++ programs based on the computer architecture.

Part 1 Use an nint, which is aliased to the IntPtr type. When calling a C++ method from a DLL, nint can be a useful syntax feature.

Part 2 Use an IntPtr, which has the same result and same type as the nint. The code is less elegant.

Part 3 With the nuint type, we have an alias to the UIntPtr type, which is unsigned (no negative values are represented).

Part 4 UIntPtr is the type to which the nuint type is aliased. In some programs, specifying UIntPtr can be hard to read, while nuint is clearer.

Part 5 We show the maximum values of nint and uint, along with the IntPtr and UIntPtr types.

using System;

// Part 1: use an nint.
nint test = 10;
Console.WriteLine(test);
Console.WriteLine(typeof(nint));

// Part 2: use an IntPtr.
IntPtr test2 = 10;
Console.WriteLine(test2);
Console.WriteLine(typeof(IntPtr));

// Part 3: use an nuint.
nuint test3 = 1000;
Console.WriteLine(test3);
Console.WriteLine(typeof(nuint));

// Part 4: use an UIntPtr.
UIntPtr test4 = 1000;
Console.WriteLine(test4);
Console.WriteLine(typeof(UIntPtr));

// Part 5: some maximums.
Console.WriteLine(nint.MaxValue);
Console.WriteLine(IntPtr.MaxValue);
Console.WriteLine(nuint.MaxValue);
Console.WriteLine(UIntPtr.MaxValue);10
System.IntPtr
10
System.IntPtr
1000
System.UIntPtr
1000
System.UIntPtr
9223372036854775807
9223372036854775807
18446744073709551615
18446744073709551615

Int is found in almost every program, while uint is less common. Int is exceedingly useful and simple to understand, and can be considered the default number type.

Int

Int example