[C #] Simple and fast to convert various numeric words to numbers (String to int)

I believe that when you are writing programs, you must have a lot of opportunities to convert numeric strings into int or float type values, but the numeric characters may not be very clean, sometimes there are thousands Quantile, currency symbol, blanks before and after, or even not decimal, so the conversion is a bit tiring, like thousandths or currency symbols, I used Replace to delete symbols such as $ and then convert them, but if you use them. Net Framework 2.0 and above are actually not so troublesome, there are built-in functions to help you deal with these miscellaneous things, let us see how to do it.

I believe that when you are writing programs, you must have a lot of opportunities to convert numeric strings into int or float type values, but the numeric characters may not be very clean, sometimes There will be thousands, currency symbols, blanks before and after, or even not decimal, so the conversion is a bit tiring, like the thousands or currency symbols, I used Replace to delete symbols such as $ and then convert them, but if If you are using .Net Framework 2.0 or above, it doesn’t have to be so troublesome. There are built-in functions to help you deal with these miscellaneous things. Let’s see how to do it.

Use int.Parse or int.TryParse

If you read it right, it is int.Parse. You can use int.Parse to contain thousands, String transformation of currency symbol.

Maybe you will say that I lied to you, then you must have not looked at the other parameters of the Parse method (Method), Parse has a parameter System.Globalization.NumberStyles enumeration type (Enum) is used to declare the allowed style of the incoming string, and the members of NumberStyles are as follows:

< tr>

Name	Description
None	It must be exactly a decimal integer number.
AllowLeadingWhite	Allow white space before the number.
AllowTrailingWhite	Allow white space after the number.
AllowLeadingSign	Allow signs in front of numbers .
AllowTrailingSign	Allow sign behind the number .
AllowParentheses	Allows a pair of brackets to enclose numbers , The brackets indicate that the string to be parsed represents a negative number.
AllowDecimalPoint	Numerical strings can have decimal points.
AllowThousands	The numeric string can contain group separation symbol.
AllowExponent	Numerical strings can use exponential notation .
AllowCurrencySymbol	The numeric string can contain currency symbols.
AllowHexSpecifier	Use hexadecimal for numeric strings Value, but cannot add “0x” or “&h” in front of it.

The following are the combination members:

< tr>

Name	Description
Integer	AllowLeadingWhite | AllowTrailingWhite | AllowLeadingSign.
HexNumber	AllowLeadingWhite | AllowTrailingWhite | AllowHexSpecifier.
Number	AllowLeadingWhite | AllowTrailingWhite | AllowLeadingSign | AllowTrailingSign | AllowDecimalPoint | AllowThousands.
Float	AllowLeadingWhite | AllowTrailingWhite | AllowLeadingSign | AllowDecimalPoint | AllowExponent.
Currency	All except AllowExponent and AllowHexSpecifier model.
Any	All modes except AllowHexSpecifier.

This is only a brief table. For details, please see [MSDN] NumberStyles enumeration type.

The default NumberStyles used by int.Parse is Integer. Integer only allows blank and addition and subtraction modes, so pass in others.

There are other numeric ValueTypes such as decimal.Parse, float.Parse, byte.Parse, short.Parse, etc., which support the use of NumberStyles, because in fact they are all used The same Class handles the conversion, but the NumberStyles used are different. For example, decimal.Parse uses NumberStyles.Currency by default.

TryParse is a better method for conversion, because Parse is that the format of the value is incorrect and an Exception will be thrown. If the program is not written well, the program may be closed, but TryParse is different. Incorrect format only does not return the converted value, it will not cause disaster for the big too (but not necessarily, because the variable that used TryParse to receive the converted value in the original case must have a value, but the conversion failed and nothing else was done. In the end, NullReferenceException may still be generated. To avoid such problems, you can refer to the spirit of defensive programming (Defensive programming).

Usage example

//Contains thousandths

int value1 = int.Parse("1,000,000", NumberStyles.AllowThousands);

int value2 = (int)decimal.Parse("1,000,000"); //Of course, decimal.Parse can also be used, just to transform



//But if you have decimals, you can’t use int. Parse will fail

int value3 = (int)decimal.Parse("1,000,000.50", NumberStyles.AllowThousands | NumberStyles.AllowDecimalPoint);



//A currency symbol is also ok, but the $ and the number cannot be separated, but the computer’s cultural setting is used

int value4 = int.Parse("NT$1,000,000", NumberStyles.AllowCurrencySymbol | NumberStyles.AllowThousands);



//You can also use the cultural settings of different countries

int value5 = int.Parse("$1,000,000", NumberStyles.Any, CultureInfo.GetCultureInfo("en")); //United States

int value6 = int.Parse("￥1,000,000", NumberStyles.Any, CultureInfo.GetCultureInfo("ja")); //Japan



//Index

int value7 = int.Parse("1E+6", NumberStyles.AllowExponent);



//parentheses

int value8 = int.Parse("(1,000,000)", NumberStyles.AllowParentheses | NumberStyles.AllowThousands);



/hexadecimal

int value9 = int.Parse("F4240",NumberStyles.HexNumber);



//Blank before and after

int value10 = int.Parse(" 1000000 ",NumberStyles.AllowLeadingWhite | NumberStyles.AllowTrailingWhite);



//But the percentage value is not supported, additional processing is required

int str = "10.5%";

if (str.IndexOf(‘%‘)>-1)

{

 int value11 = decimal.Parse(str.TrimEnd(new char[] {‘%‘,‘ ‘})) / 100M;

}



//2 or octal, use another Method

int value12 = Convert.ToInt32("11110100001001000000", 2);

int value13 = Convert.ToInt32("3641100", 8);



//If you are lazy, you can write like this, but the performance will be a little bit worse

int value14 = (int)decimal.Parse("1,000,000", NumberStyles.Any);

Reference data

[MSDN]NumberStyles enumeration type

[Wikipedia]Defensive programming

Original: Large column [C#] Convert various numerical characters into numbers (string to int) simply and quickly