string-formatting

问题 I'm trying to define a class method for debug prints that will behave like printf : inline void debug(const char* fmt, ...) __attribute__ ((format (printf, 1, 2))) This complains about: error: format string argument not a string type I recalled that a class method declaration has an implicit this parameter, so I changed the locations of the parameters to 2, 3: inline void debug(const char* fmt, ...) __attribute__ ((format (printf, 2, 3))) and now it compiles, but it looks like the parameters

问题 I was wondering if there's a syntax for formatting NULL values in string.Format, such as what Excel uses For example, using Excel I could specify a format value of {0:#,000.00;-#,000.00,NULL} , which means display the numeric value as number format if positive, number format in parenthesis if negative, or NULL if the value is null string.Format("${0:#,000.00;(#,000.00);NULL}", someNumericValue); Edit I'm looking for formatting NULL / Nothing values for all data types, not just numeric ones.

问题 I am creating a lightweight editor in C# and would like to know the best method for converting a string into a nicely formatted XML string. I would hope that there's a public method in the C# library like "public bool FormatAsXml(string text, out string formattedXmlText)", but it couldn't be that easy, could it? Very specifically, what would the method "SomeMethod" have to be that would produce the output below? string unformattedXml; string formattedXml; unformattedXml = "<?xml version=\"1.0

问题 This question already has answers here : C++: “std::endl” vs “\n” (13 answers) Closed 2 years ago . Is there a reason to use endl with cout when I can just use \n ? My C++ book says to use endl, but I don't see why. Is \n not supported as widely as endl , or am I missing something? 回答1: endl appends '\n' to the stream and calls flush() on the stream. So cout << x << endl; is equivalent to cout << x << '\n'; cout.flush(); A stream may use an internal buffer which gets actually streamed when

问题 On a EN-US regional system, what does B or b represent in a format mask? While it does nothing in VBA's Format function, both the TEXT function and Custom Number Formatting recognize b as a legal Number Format Code and return a number that I cannot determine the origin of. To further confuse matters, larger numbers return different values when formatted with bbbb and while blocks of sequential numbers return the same value, there are transitions when they jump ahead a digit. I do know that

问题 Is there any way so that i can show only first character of a Bound string on a textblock..? For eg;If i Bind 'Male', my textblock should only show 'M'..... 回答1: You might use a value converter to return a string prefix: class PrefixValueConverter : IValueConverter { public object Convert(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture) { string s = value.ToString(); int prefixLength; if (!int.TryParse(parameter.ToString(), out prefixLength) || s

问题 I have a variable of type double , I need to print it in upto 3 decimals of precision but it shouldn't have any trailing zeros... eg. I need 2.5 // not 2.500 2 // not 2.000 1.375 // exactly till 3 decimals 2.12 // not 2.120 I tried using DecimalFormatter , Am i doing it wrong? DecimalFormat myFormatter = new DecimalFormat("0.000"); myFormatter.setDecimalSeparatorAlwaysShown(false); Thanks. :) 回答1: Try the pattern "0.###" instead of "0.000" : import java.text.DecimalFormat; public class Main {

问题 What's the difference between these 2 string format statements in Python: '{0}'.format(a) '{0!s}'.format(a) Both have the same output if a is an integer, list or dictionary. Is the first one {0} doing an implicit str() call? Source PS: keywords: exclamation / bang "!s" formatting 回答1: It is mentioned in the documentation: The conversion field causes a type coercion before formatting. Normally, the job of formatting a value is done by the __format__() method of the value itself. However, in

问题 I have strings of the form Version 1.4.0\n and Version 1.15.6\n , and I'd like a simple way of extracting the three numbers from them. I know I can put variables into a string with the format method; I basically want to do that backwards, like this: # So I know I can do this: x, y, z = 1, 4, 0 print 'Version {0}.{1}.{2}\n'.format(x,y,z) # Output is 'Version 1.4.0\n' # But I'd like to be able to reverse it: mystr='Version 1.15.6\n' a, b, c = mystr.unformat('Version {0}.{1}.{2}\n') # And have

问题 How do I get an integer to fill 0's to a fixed width in python 3.2 using the format attribute? Example: a = 1 print('{0:3}'.format(a)} gives ' 1' instead of '001' I want. In python 2.x, I know that this can be done using print "%03d" % number. I checked the python 3 string documentation but wasn't able to get this. http://docs.python.org/release/3.2/library/string.html#format-specification-mini-language Thanks. 回答1: Prefix the width with a 0 : >>> '{0:03}'.format(1) '001' Also, you don't need