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How to parse a string into a nullable int in C#?
C# provides a special data types, the nullable types, to which you can assign normal range of values as well as null values.
C# 2.0 introduced nullable types that allow you to assign null to value type variables. You can declare nullable types using Nullable where T is a type.
Nullable types can only be used with value types.
The Value property will throw an InvalidOperationException if value is null; otherwise it will return the value.
The HasValue property returns true if the variable contains a value, or false if it is null.
You can only use == and != operators with a nullable type. For other comparison use the Nullable static class.
Nested nullable types are not allowed. Nullable<Nullable<int>> i; will give a compile time error.
Example 1
static class Program{
static void Main(string[] args){
string s = "123";
System.Console.WriteLine(s.ToNullableInt());
Console.ReadLine();
}
static int? ToNullableInt(this string s){
int i;
if (int.TryParse(s, out i)) return i;
return null;
}
}Output
123
When Null is passed to the extenstion method it doesn't print any value
static class Program{
static void Main(string[] args){
string s = null;
System.Console.WriteLine(s.ToNullableInt());
Console.ReadLine();
}
static int? ToNullableInt(this string s){
int i;
if (int.TryParse(s, out i)) return i;
return null;
}
}Output
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