C# difficulties are solved one by one (7): checked and unchecked

C# By default, if the value of a constant expression exceeds the maximum value of the target type, a compilation error will occur.

If the target data type cannot accommodate the data of non-constant expressions, the data will be truncated during assignment.

class Program 
{ 
static void Main(string[] args) 
{ 
int n = int.MaxValue;//n=2147483647 
n = n + 1; 
System.Console.WriteLine(n); 
} 
}

At this time, it can be explained by memory storage data. Previously, int.MaxValue was 32-bit 1 in the memory. After adding 1, it becomes 32-bit 0. At this time, 0 is considered to be a negative sign, so it will be obtained -2147483648.

Placing the above code in the checked block will cause a System.OverflowException type.

class Program 
{ 
static void Main(string[] args) 
{ 
checked 
{ 
int m = int.MaxValue; 
m = m + 1; 
System.Console.WriteLine(m); 
} 
} 
}

For variables placed in checked blocks in C#, if an overflow assignment occurs during runtime, an exception will be thrown.

unchecked is used to cancel overflow checking of integer arithmetic operations and conversions.

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