When working with data, you will inevitably need to convert data from one type to another.

For example, suppose you are building a calculator and you want to capture input from the user. You would typically do it as follows:

Console.WriteLine("Enter first number:");
var firstInput = Console.ReadLine();
Console.WriteLine("Enter second number:");
var secondInput = Console.ReadLine();

var first = int.Parse(firstInput);
var second = int.Parse(secondInput);

Console.WriteLine($"The result is: {first + second}");

The trouble with this code is that it assumes that the user will enter a valid number.

This is not a valid assumption to make!

You need to be proactive and catch the inevitable exception that may arise.

Console.WriteLine("Enter first number:");
var firstInput = Console.ReadLine();
Console.WriteLine("Enter second number:");
var secondInput = Console.ReadLine();

int first, second;
try
{
    first = int.Parse(firstInput);
}
catch (Exception e)
{
    Console.WriteLine("Invalid first number");
    return;
}

try
{
    second = int.Parse(secondInput);
}
catch (Exception e)
{
    Console.WriteLine("Invalid second number");
    return; 
}

Console.WriteLine($"The result is: {first + second}");

Better.

An even better technique is to take advantage of the fact that parsing inputs is an exercise that is very likely to have invalid inputs, and using Exceptions to manage control flow is expensive.

Most conversion methods have a TryParse method designed for this purpose.

We can rewrite our code as follows:

int first, second;
Console.WriteLine("Enter first number:");
while (!int.TryParse(Console.ReadLine(), out first)) ;
Console.WriteLine("Enter second number:");
while (!int.TryParse(Console.ReadLine(), out second)) ;

Console.WriteLine($"The result is: {first + second}");

The magic is taking place here:

int.TryParse(Console.ReadLine(), out first)

This method attempts to parse the input and store it in the out variable first. If it succeeds, it will do just that and return true,

If it fails, it will return false.

You can check this return value to determine what happened.

We are taking advantage of this to write a loop, where we will only proceed if a valid number is keyed in.

while (!int.TryParse(Console.ReadLine(), out first)) ;

If we run this and enter some input, we get the following results:

Enter first number:
monkey
sdf
60
Enter second number:
uu
jjj
jj
70
The result is: 130

Most key data types have such a method:

TLDR

Most types have a TryParse method that you can use to attempt conversion and verify success or otherwise before proceeding with your logic.

The code is in my GitHub.

Happy hacking!