boost::locale::basic_format< CharType > Class Template Reference

a printf like class that allows type-safe and locale aware message formatting More...

#include <boost/locale/format.hpp>

Public Types
typedef CharType	char_type
	Underlying character type.
typedef basic_message< char_type >	message_type
typedef std::basic_string< CharType >	string_type
	string type for this type of character
typedef std::basic_ostream< CharType >	stream_type
	output stream type for this type of character

Public Member Functions
	basic_format (const string_type &format_string)
	Create a format class for format_string.
	basic_format (const message_type &trans)
	basic_format (const basic_format &other)=delete
	Non-copyable.
void	operator= (const basic_format &other)=delete
	basic_format (basic_format &&other)
	Moveable.
basic_format &	operator= (basic_format &&other)
template<typename Formattible >
basic_format &	operator% (const Formattible &object)
string_type	str (const std::locale &loc=std::locale()) const
	Format a string using a locale loc.
void	write (stream_type &out) const
	write a formatted string to output stream out using out's locale

Detailed Description

template<typename CharType>
class boost::locale::basic_format< CharType >

a printf like class that allows type-safe and locale aware message formatting

This class creates a formatted message similar to printf or boost::format and receives formatted entries via operator %.

For example

std::cout << format("Hello {1}, you are {2} years old") % name % age << std::endl;

Formatting is enclosed between curly brackets { } and defined by a comma separated list of flags in the format key[=value] value may also be text included between single quotes ' that is used for special purposes where inclusion of non-ASCII text is allowed

Including of literal { and } is possible by specifying double brackets {{ and }} accordingly.

For example:

std::cout << format("The height of water at {1,time} is {2,num=fixed,precision=3}") % time % height;

The special key – a number without a value defines the position of an input parameter. List of keys:

• [0-9]+ – digits, the index of a formatted parameter – mandatory key.
• num or number – format a number. Optional values are:
  • hex – display hexadecimal number
  • oct – display in octal format
  • sci or scientific – display in scientific format
  • fix or fixed – display in fixed format
  For example number=sci
• cur or currency – format currency. Optional values are:
  • iso – display using ISO currency symbol.
  • nat or national – display using national currency symbol.
• per or percent – format percent value.
• date, time , datetime or dt – format date, time or date and time. Optional values are:
  • s or short – display in short format
  • m or medium – display in medium format.
  • l or long – display in long format.
  • f or full – display in full format.
• ftime with string (quoted) parameter – display as with strftime see, as::ftime manipulator
• spell or spellout – spell the number.
• ord or ordinal – format ordinal number (1st, 2nd... etc)
• left or < – align to left.
• right or > – align to right.
• width or w – set field width (requires parameter).
• precision or p – set precision (requires parameter).
• locale – with parameter – switch locale for current operation. This command generates locale with formatting facets giving more fine grained control of formatting. For example:

  std::cout << format("Today {1,date} ({1,date,locale=he_IL.UTF-8@calendar=hebrew,date} Hebrew Date)") % date;

• timezone or tz – the name of the timezone to display the time in. For example:
  

  std::cout << format("Time is: Local {1,time}, ({1,time,tz=EET} Eastern European Time)") % date;

• local - display the time in local time
• gmt - display the time in UTC time scale

  std::cout << format("Local time is: {1,time,local}, universal time is {1,time,gmt}") % time;

Invalid formatting strings are slightly ignored. This would prevent from translator to crash the program in unexpected location.

Member Typedef Documentation

message_type

template<typename CharType>

typedef basic_message<char_type> boost::locale::basic_format< CharType >::message_type

The translation message type

Constructor & Destructor Documentation

basic_format()

template<typename CharType>

boost::locale::basic_format< CharType >::basic_format ( const message_type &  trans )

inline

Create a format class using message trans. The message if translated first according to the rules of the target locale and then interpreted as a format string

Member Function Documentation

operator%()

template<typename CharType>

template<typename Formattible >

basic_format& boost::locale::basic_format< CharType >::operator% ( const Formattible &  object )

inline

Add new parameter to the format list. The object should be a type with defined expression out << object where out is std::basic_ostream.

A reference to the object is stored, so do not store the format object longer than the lifetime of the parameter. It is advisable to directly print the result:

basic_format<char> fmt("{0}");
fmt % (5 + 2); // INVALID: Dangling reference
int i = 42;
return fmt % i; // INVALID: Dangling reference
std::cout << fmt % (5 + 2); // OK, print immediately
return (fmt % (5 + 2)).str(); // OK, convert immediately to string

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The documentation for this class was generated from the following file:

• boost/locale/format.hpp