Input string was not in a correct format ошибка

Problems

There are some possible cases why the error occurs:

1. Because textBox1.Text contains only number, but the number is too big/too small

2. Because textBox1.Text contains:

   • a) non-number (except space in the beginning/end, - in the beginning) and/or
   • b) thousand separators in the applied culture for your code without specifying NumberStyles.AllowThousands or you specify NumberStyles.AllowThousands but put wrong thousand separator in the culture and/or
   • c) decimal separator (which should not exist in int parsing)

NOT OK Examples:

Case 1

a = Int32.Parse("5000000000"); //5 billions, too large
b = Int32.Parse("-5000000000"); //-5 billions, too small
//The limit for int (32-bit integer) is only from -2,147,483,648 to 2,147,483,647

Case 2 a)

a = Int32.Parse("a189"); //having a 
a = Int32.Parse("1-89"); //having - but not in the beginning
a = Int32.Parse("18 9"); //having space, but not in the beginning or end

Case 2 b)

NumberStyles styles = NumberStyles.AllowThousands;
a = Int32.Parse("1,189"); //not OK, no NumberStyles.AllowThousands
b = Int32.Parse("1,189", styles, new CultureInfo("fr-FR")); //not OK, having NumberStyles.AllowThousands but the culture specified use different thousand separator

Case 2 c)

NumberStyles styles = NumberStyles.AllowDecimalPoint;
a = Int32.Parse("1.189", styles); //wrong, int parse cannot parse decimal point at all!

Seemingly NOT OK, but actually OK Examples:

Case 2 a) OK

a = Int32.Parse("-189"); //having - but in the beginning
b = Int32.Parse(" 189 "); //having space, but in the beginning or end

Case 2 b) OK

NumberStyles styles = NumberStyles.AllowThousands;
a = Int32.Parse("1,189", styles); //ok, having NumberStyles.AllowThousands in the correct culture
b = Int32.Parse("1 189", styles, new CultureInfo("fr-FR")); //ok, having NumberStyles.AllowThousands and correct thousand separator is used for "fr-FR" culture

Solutions

In all cases, please check the value of textBox1.Text with your Visual Studio debugger and make sure that it has purely-acceptable numerical format for int range. Something like this:

1234

Also, you may consider of

1. using TryParse instead of Parse to ensure that the non-parsed number does not cause you exception problem.

2. check the result of TryParse and handle it if not true

   int val;
   bool result = int.TryParse(textbox1.Text, out val);
   if (!result)
       return; //something has gone wrong
   //OK, continue using val
   

The input string was not in a correct format error might occur when you try to convert a non-numeric string from the input into an int. Moreover, you’ll get the said error while storing the input values that are larger than the range of the int data type as int. This post explains the causes stated above to give you clarity before you read about the solutions.

Continue reading to see how to solve the error and get your program back on track.

Why the Input String Was Not in a Correct Format Error Occur?

The given error occurs when you attempt to convert non-numeric data into an int. Also, exceeding the limit of the int data type to store larger values will give you the same error. Here are the detailed explanations of the causes:

– Converting the Non-numeric Data in Text Boxes Into Int

Are you working on a Windows Form and getting the above error? Well, the issue might be with converting the data of the empty text boxes when the form loads for the first time. So, here the erroneous code might be the one that attempts to convert an empty string from the text box into an int.

This line of code might throw the mentioned error when called inside the constructor:

lucky_number = Int32.Parse(luckyTextBox.Text);

– You Are Using Int With Input Values Larger than the Int Range

If the input provided by the user is larger than the range of int data type and you attempt to store the same in an int column, then the stated error occurs.

How To Fix the Format Error Found With the Strings?

You can fix the given error by putting into use the below solutions as per your need:

– Use the Int.TryParse() Method

As the text boxes are always empty when the form is loaded for the first time, you should use the Int.TryParse() method instead of the Int32.Parse() method. It will ensure that the error isn’t thrown even if the empty strings are attempted to be converted.

Replace the above line of code with the following:

lucky_number = Int.TryParse(luckyTextBox.Text);

– Use Varchar Instead of Int To Fix the Input String Was Not in a Correct Format Error

You should use the varchar data type instead of int to store any values that are larger than the range of int. It will most probably solve the error.

FAQ

Here you’ll find some additional information that will help you in your coding routine:

– What Is an ‘Input’ String?

An ‘input’ string refers to the data passed to a computer through a peripheral device such as a keyboard. A good example of this can be the data that you fill in the text boxes of an online form.

– How To Ensure That the ‘Input’ String Matches a Particular Format?

You can use a variety of methods including the regular expressions and loops to check if the given input string matches a particular format. Indeed, the regular expressions offer a quick and easy way to ensure the correctness of the string format. Moreover, using the loops can be helpful when you want to check each character of the string individually. So, it depends on your program requirements and the logic that you are trying to implement.

– How To Get Rid of Number Format Exception in Java?

You can resolve the number format exception in Java by checking if the string that you are trying to parse contains a numeric value. It is because the given exception occurs when you convert a string that doesn’t fulfill the requirements of an integer data type. Now, the name of the stated exception might be clear to you as well.

Conclusion

You don’t need to be worried anymore regarding the error discussed in this article. Indeed, it can be solved easily if you implement the stated solutions. Please look here for one-liner solutions:

• Input string was not in a correct format error occurs when you convert non-numeric data into an int or exceed the limit of the int data type.
• You should use Int.TryParse instead of Int32.Parse method to get rid of the said error
• You should store large numeric values in a column with a varchar data type

Never forget to match the destination data type with input data to avoid such kind of errors in the future.

In the first case:

int i = 20;
Console.WriteLine($" int i = { i }");

which is also identical to:

int i = 20;
Console.WriteLine($" int i = {i}");

This is called string interpolation , it’s a language feature that was introduced in C# 6.
It just provides a more readable syntax than the usage of string.Format. but the compiler just transforms it to a call to string.Format method.
You can say that it takes whatever inside the curly braces, put a number instead of it, and passes what was inside the curly braces to a the string.Format.
so spaces really doesn’t matter here.

To make things more simpler:
You can say that you write a REAL C# expression inside the curly braces. Does it make sense that the spaces in that case should make a different ?
For Example:
Aren’t the following two lines the same ?

Console.WriteLine( i );
Console.WriteLine(i);

In the second case:

 int i = 20;
Console.WriteLine("int i = {0}", i);

Inside of the .NET Framework, the arguments of Console.WriteLine are passed to string.Format, and this is just how string.Format works.

In the third case:

 int i = 20;
Console.WriteLine("int i = { 0 }", i);

Short answer: This is not how string.Format should work, string.Format expects {number} without any spaces. Nothing more, Nothing less.

Long answer: That will require going a little bit deep inside the .NET source code. The real magic that causes string.Format to really do its job is an internal method called AppendFormatHelper. That method was designed to expect a number between the curly braces without additional spaces.