wrong result from multiplication operation

Question

I am trying to multiply two numbers in my application but in some case it result wrong value

var result = 0;
var firstNumber = 654165;
var secondNumber = 6541;
result = firstNumber * secondNumber;

it result -16074031 which is wrong

can you help me to found where is the error?

Answer 1

Try this:

checked
{
    var result = 0;
    var firstNumber = 654165;
    var secondNumber = 6541;
    result = firstNumber * secondNumber;
}

this way you can see the problem System.OverflowException. To solve simply use long

unchecked
{
    var result = 0L;
    var firstNumber = 654165L;
    var secondNumber = 6541L;
    result = firstNumber * secondNumber;
}

Take a look at checked and unchecked keywords.