Simple C# multiplication table program

Question

I'm pretty new to C# and have decided that I wanted to make a program that calculate the multiplication table of a selected number to practice on loops etc. I'm pretty satisfied, but I wondered if there is anything I can do to make the code better and more concise.

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
namespace Multiplication
{
 class Program
 {
 static void Main(string[] args)
 {
 Console.WriteLine("Write a number and I'll calculate the multiplication table of the number");
 int userValue_number = int.Parse(Console.ReadLine());
 Console.WriteLine("How far do you want to go? E.g. 12, then {0} x 12 is the highest I will go ", userValue_number); 
 int userValue_length = int.Parse(Console.ReadLine());
 int n = userValue_number;
 int i = 1;
 while (n <= (userValue_number * userValue_length))
 {
 Console.WriteLine("{0} x {1} = {2}", i, userValue_number, n);
 n=n+userValue_number;
 i++;
 }
 Console.ReadLine();
 }
 }
}

Answer 1

int.Parse will throw an exception if input isn't an integer. Consider using int.TryParse instead.

You should verify that the user doesn't enter a negative integer for the 2nd argument.

Your while loop should be a for loop.

A multiplication isn't much more expensive than an addition, especially compared with the performance cost of calling Console.WriteLine; so I'd use multiplication instead if that makes the code clearer:

for (int i = 1; i <= userValue_length ; ++i)
{
 Console.WriteLine("{0} x {1} = {2}", i, userValue_number, i * userValue_number);
}

userValue_number is a strange mix of camelCase and using_underscores. camelCase is more conventional in C#. I think I'd rename those to chosenNumber and chosenTimes or something like that.

The final Console.ReadLine(); is ugly and uncessary. You probably use it for debugging; instead (to inspect output from a debugger session before the console window auto-closes) put a debugger breakpoint on the final curly brace of main.

Your message E.g. 12, then {0} x 12 is ... doesn't match your output {0} x {1} = ...; instead i should be the 2nd (not 1st) number in your output.

• SylvainD: Also, this version is not affected by infinite loops like OP's version (when userValue_number is 0)
• ChrisW: I'd upvote that if you post it as a separate answer (because I especially admire code reviews which find bugs).