This occurs when the attempt to convert a string value to any other base type fails because the string is not in the proper format. An InvalidCastException is thrown for the following conversions:Ĭonversions from Char to Boolean, Single, Double, Decimal, or DateTime.Ĭonversions from Boolean, Single, Double, Decimal, or DateTime to Char.Ĭonversions from DateTime to any other type except String.Ĭonversions from any other type, except String, to DateTime.Ī FormatException. This occurs when a particular conversion is not supported. In this case, the method simply returns an instance of the original type.Īn InvalidCastException. This occurs when an attempt is made to convert from a type to itself (for example, by calling Convert.ToInt32(Int32) with an argument of type Int32). However, the actual call to a particular conversion method can produce one of five outcomes, depending on the value of the base type at run time and the target base type. This article consists of the following sections:Ĭonversions to and from Base Types Non-Decimal Numbers Conversions from Custom Objects to Base Types Culture-Specific Formatting Information Base64 Encoding Other Common ConversionsĪ conversion method exists to convert every base type to every other base type. In addition, the Convert class includes methods to support other kinds of conversions. The supported base types are Boolean, Char, SByte, Byte, Int16, Int32, Int64, UInt16, UInt32, UInt64, Single, Double, Decimal, DateTime and String. The static methods of the Convert class are primarily used to support conversion to and from the base data types in. "optional sign followed by a series of digits" ) Ĭonsole::WriteLine( "Overflow in string to Int32 conversion" ) Ĭonsole::WriteLine( "Your integer as a Double is ", _ NewInteger = Convert::ToInt32( System::Console::ReadLine() ) Ĭonsole::WriteLine( "String does not consist of an " + System::Console::ReadLine() returns a string and itĬonsole::WriteLine( "Enter an integer:" ) String^ strNumber = Convert::ToString( dNumber ) Ĭhar chrNumber = Convert::ToChar( strNumber->Substring( 0, 1 ) ) Ĭonsole::WriteLine( "String length is greater than 1" ) "Overflow in Double to Int32 conversion" ) īoolean bNumber = Convert::ToBoolean( dNumber ) Int32 iNumber = Convert::ToInt32( dNumber ) using System Ĭonsole.WriteLine($"Unable to parse '", ++numVal) Ĭonsole.WriteLine("numVal cannot be incremented beyond its current value") Ĭonsole.WriteLine("Input string is not a sequence of digits.") Ĭonsole.WriteLine("The number cannot fit in an Int32.The following example demonstrates some of the conversion methods in the Convert class, including ToInt32, ToBoolean, and ToString. The following example demonstrates both successful and unsuccessful calls to Parse and TryParse. You can check for a null or empty string before attempting to parse it by calling the String.IsNullOrEmpty method. A string whose value is null or String.Empty fails to parse successfully. 3" (note the embedded space), "10e1" ( float.TryParse works here), and so on. For example, you can use decimal.TryParse to parse "10", "10.3", or " 10 ", but you can't use this method to parse 10 from "10X", "1 0" (note the embedded space), "10. Any white space within the string that forms the number causes an error. The Parse and TryParse methods ignore white space at the beginning and at the end of the string, but all other characters must be characters that form the appropriate numeric type ( int, long, ulong, float, decimal, and so on). When calling a Parse method, you should always use exception handling to catch a FormatException when the parse operation fails. If the string isn't in a valid format, Parse throws an exception, but TryParse returns false. The Parse method returns the converted number the TryParse method returns a boolean value that indicates whether the conversion succeeded, and returns the converted number in an out parameter. The Convert.ToInt32 method uses Parse internally. You use Parse or TryParse methods on the numeric type you expect the string contains, such as the System.Int32 type. Using a Convert method is more useful for general objects that implement IConvertible. It's slightly more efficient and straightforward to call a TryParse method (for example, int.TryParse("11", out number)) or Parse method (for example, var number = int.Parse("11")). You convert a string to a number by calling the Parse or TryParse method found on numeric types ( int, long, double, and so on), or by using methods in the System.Convert class.
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