I get Input string was not in a correct format. error

[Soren Lyder Nielsen]

I Get this error, when I write a number in my textBox1, and then erase it again.. Then this popup appers: An unhandled exception of type 'System.FormatException' occurred in mscorlib.dll Additional information: Input string was not in a correct format. Code:

private: System::Void textBox1_TextChanged(System::Object^ sender, System::EventArgs^ e) {
double tysk, ti, femten, tyve, dansk;
tysk = System::Convert::ToDouble(textBox1->Text);

         dansk = tysk \* 7.5;
         ti = tysk \* 7.5 \* 0.90;
         femten = tysk \* 7.5 \* 0.85;
         tyve = tysk \* 7.5\* 0.80;
         
         label7->Text = System::Convert::ToString(dansk);
         label8->Text = System::Convert::ToString(ti);
         label9->Text = System::Convert::ToString(femten);
         label10->Text = System::Convert::ToString(tyve);
     }

};

It also appers when I type a letter in the teksBox1. Otherwise it workd fine. Its just a simlpe calculator.

[Lost User]

tysk = System::Convert::ToDouble(textBox1->Text);

This will always throw an exception if the contents of teksBox1 is not a number. You should either catch the exception and deal with it, or use the TryParse[^] method.

Use the best guess

[Lost User]

Look this Example .. it will help.

int a= Convert::ToInt32(this->textBox1->Text->Trim());
int b= Convert::ToInt32(this->textBox2->Text->Trim());
int sum=a+b;

"The more quieter you become, the more you are able to hear..."

[User 9966263]

Use this instead of "Convert::ToString()" function int a = 287; String ^b = ""; b += a;