I need to convert a string to a float....

glennPattonWork3

Hi All,... I am reading into a rich text box a small number (0.385 to 0.457) which is read into a Rich Text Box as a string and my though was to use Text.ConvertTo(float) in the following way

Value_Extract = ((Convert.ToDecimal(rtbIncoming.Text));

Value_Extract is a float... This does not work compiles and Bang falls over when run, had look on Stack Overflow they seem to do in a similar way. Is this the correct way?? As VS helpfully tells me I need to cast a float as a decimal, decimal.tryparse??

Ron Nicholson

I typically use float.TryParse(string, out float result); This returns true if successful and false if not. HTH

Jack of all trades, master of none, though often times better than master of one.

glennPattonWork3

Hi, Thanks for that float.TryParse(), will I be able to get out as a floating point?..

Richard Deeming

Are you sure it compiles? String doesn't have a ConvertTo method, and you can't pass the Decimal type as an argument like that. Assuming the text is a valid number, then Convert.ToSingle(rtdData.Text) should give you a float back. Or Convert.ToDecimal(rtdData.Text) would give you a decimal, which you would then have to cast to store in a float variable. But these methods will throw an exception if the text is not a valid number. It would be better to use float.TryParse / decimal.TryParse so that you can notify the user if the value can't be parsed.

"These people looked deep within my soul and assigned me a number based on the order in which I joined." - Homer

glennPattonWork3

Okay, I will give that a go... It hasn't crashed yet!!

OriginalGriff

Yes:

if (float.TryParse(myTextBox.Text, out float result))
{
Console.WriteLine(result);
}

"I have no idea what I did, but I'm taking full credit for it." - ThisOldTony "Common sense is so rare these days, it should be classified as a super power" - Random T-shirt AntiTwitter: @DalekDave is now a follower!

Bosse62

Is there a problem with the decimal sign; period or comma?

glennPattonWork3

Old question now solved!

CharHen

With this extension we can parse strings directly to a numeric type

static bool Fail<T>(this object _, out T item) where T : struct
{
item = default;
return false;
}

static bool Pass<T>(this object obj, out T item) where T : struct
{
Type conversionType = typeof(T);
item = (T)Convert.ChangeType(obj, conversionType);
return true;
}

const string System_Int16 = "System.Int16";

const string System_UInt16 = "System.UInt16";

const string System_Int32 = "System.Int32";

const string System_Int64 = "System.Int64";

const string System_UInt32 = "System.UInt32";

const string System_Single = "System.Single";

const string System_Double = "System.Double";

const string System_UInt64 = "System.UInt64";

const string System_Byte = "System.Byte";

const string System_Decimal = "System.Decimal";

const string System_SByte = "System.SByte";

const string System_Numerics_BigInteger = "System.Numerics.BigInteger";

public static bool TryParse<T>(this string value, out T item) where T : struct
{
var conversionType = typeof(T);
var floatType = typeof(float);
var doubleType = typeof(double);
var decimalType = typeof(decimal);
if(conversionType != floatType && conversionType != doubleType
&& conversionType != decimalType && value.Contains('.'))
{
//we're not converting to float, double or decimal
//there's no rounding, we just drop everything from the "."
value = value.Remove(value.LastIndexOf('.'));
}
return conversionType.FullName switch
{
System_Int16 => short.TryParse(value, out var result) ?
result.Pass(out item) : value.Fail(out item),

    System_UInt16 => ushort.TryParse(value, out var result) ?
            result.Pass(out item) : value.Fail(out item),

    System_Decimal => decimal.TryParse(value, out var result) ?
            result.Pass(out item) : value.Fail(out item),

    System_Int32 => int.TryParse(value, out var result) ?
            result.Pass(out item) : value.Fail(out item),

    System_Int64 => long.TryParse(value, out var result) ?
            result.Pass(out item) : value.Fail(out item),

    System_UInt64 => ulong.TryParse(value, out var result) ?
            result.Pass(out item) : value.Fail(out item),

    System_UInt32 => uint.TryParse(value, out var result) ?
            result.Pass(out item) : value.Fail(out item),

    System_Single => float.TryParse(value, out var result) ?
            result.Pass(out item) : value.Fail(out item),

    System_Double => double.TryParse(value, out var result) ?
            result.Pass(out item) : value.Fail(out item),

    System_Byte => byte.TryParse(value, out var result) ?
            result.Pass(out item) : value.Fail(out item),

    System_SByte => sbyte.TryParse(value, out var result) ?
            result.Pass(out item) : value.Fail(out item),

    System_Numerics_BigInteger => BigInteger.TryParse(value, out var result) ?
            result.Pass(out item) : value.Fail(out item),

    _ => conversionType.Fail(out item)
} ;

}