32 questions
2
votes
1
answer
177
views
How boost format works in terms of c++?
I was looking at boost::format documents and just the first example made me wondering:
cout << boost::format("writing %1%, x=%2% : %3%-th try") % "toto" % 40.23 % 50;
What ...
- 1,436
1
vote
1
answer
1k
views
boost format set maximum precision of floating point
I have essentially the following:
typedef TFp double;
boost::format fmt("Floating point: %2$f");
TFp v = 0.000000001;
fmt % v;
std::cout << fmt.str();
As per the boost format manual, this ...
- 19.6k
1
vote
0
answers
73
views
boost format yield different output for seemingly same strings
Background
I am using the boost format library to format some text. My input is an uint8_t array. This is the code I used:
#include <array>
#include <vector>
#include <string>
#...
- 1,139
0
votes
1
answer
543
views
What's preventing Boost.Format form using my stream operator overload for optional int?
I want to be able to use a std::optional<int> with Boost.Format.
#include <iostream>
#include <optional>
#include <boost/format.hpp>
struct SomeType
{
int x;
};
std::...
- 5,517
1
vote
1
answer
647
views
Feeding boost::format with variadic parameters
I am attempting to write a logging function which takes a variadic argument list and prints in a safe manor.
vprintf seems like the obvious answer, but I cannot seem to find a safe way to handle when ...
- 48
0
votes
1
answer
520
views
boost::format exception under windows only
I already used boost::format in many case but I found one for which the windows implementation doesn't react as I expected because it throw an exception
boost::bad_format_string: format-string is ill-...
- 8,419
7
votes
2
answers
2k
views
Why do Boost Format and printf behave differently on same format string
The Boost Format documentation says:
One of its goal is to provide a replacement for printf, that means
format can parse a format-string designed for printf, apply it to the
given arguments, ...
- 961
2
votes
2
answers
2k
views
Boost::Format with char array
I've looked around and I've been unable to find a solution to storing what is returned from a boost format into a char array. For example:
#include "stdafx.h"
#include <iostream>
#include <...
- 304
3
votes
1
answer
560
views
How to create / combine / concatenate boost::format from multiple boost::format
This is given:
boost::format greeting("%s (Greeting)");
boost::format name("%s (Name)");
'greetingwithname' should combine and reuses 'greeting' and 'name' so that it is equivalent to this:
boost::...
- 961
-2
votes
2
answers
5k
views
Error in boost format
When I try to compile in cygwin there are problem like this:
fatal error: boost/format.hpp: No such file or directory #include
<boost/format.hpp>
How I fix this problem, someone please ...
- 29
3
votes
1
answer
2k
views
Odd behavior in boost::format hex
I'm trying to format a binary array: char* memblock to a hex string.
When I use the following:
fprintf(out, "0x%02x,", memblock[0]);
I get the following output:
0x7f,
When I try to use boost::...
- 15.5k
5
votes
2
answers
4k
views
How to use boost::format to zeropad a number where the number of decimal places is contained in a variable?
I would like to zeropad a number such that it has 5 digits and get it as a string. This can be done with the following:
unsigned int theNumber = 10;
std::string theZeropaddedString = (boost::format("...
- 5,075
11
votes
3
answers
6k
views
boost::format with variadic template arguments
Suppose I have a printf-like function (used for logging) utilizing perfect forwarding:
template<typename... Arguments>
void awesome_printf(std::string const& fmt, Arguments&&... ...
- 26.2k
26
votes
5
answers
17k
views
C++11 Equivalent to Boost.Format
Anything like Boost.Format in the C++11 standard? I've been able to avoid using Boost with a better C++11 option for every other need I've had.
For that matter, Boost.Format doesn't hold a candle to ...
- 17.7k
0
votes
3
answers
208
views
C++ variable lifetime -- need workaround to return temporary
I have a C++ object (boost::format) that has a str() function which returns an std::string.
So when I need a formatted C string, I need to write something like:
(boost::format("%1% %2%") % "1" % "2")...
- 14.3k
0
votes
1
answer
2k
views
C++ how to show exact digits of fraction part
Is there any way in C++ (or boost lib) to show a given number digits of fraction part? But I don't want to print the trailing 0 in fraction part (eg. 1.000, 1.500). See this case:
cout << std::...
- 38.2k
2
votes
2
answers
844
views
Compile-time checking of Boost.Format
Both Clang and GCC can check printf-style functions for mismatches between their format strings and their arguments. For example, they'll complain about statements like this:
printf("Hello, %s!\n");
...
- 58.2k
1
vote
2
answers
4k
views
A convenient logging statement for C++ using boost::format
I want to design a logging function with the following characteristics:
based on std::string rather than char*
supports variable number of variables, like printf
accepts as first parameter a severity ...
- 3,835
3
votes
1
answer
4k
views
c++ boost format float - how to specify that I do not want . and following zeros
I would like to use boost::format to convert a float number to string.
These are several examples for the expected results:
0.5 -> "0.5"
0 -> "0"
1.00001 -> "1"
3.66 -> "3.7"
...
- 7,192
11
votes
3
answers
10k
views
Formatting n significant digits in C++ without scientific notation
I want to format a floating point value to n significant digits but never using scientific notation (even if it would be shorter).
The format specification %f doesn't deal in significant digits, and %...
- 1,067
5
votes
2
answers
2k
views
Printing bools with boost::format as symbolic values?
How do I print boolean values with boost::format as symbolic values?
Can this be done without boost::io::group? It seems that flags sent to the stream beforehand get retested:
#include <iomanip>
...
- 20.8k
12
votes
2
answers
9k
views
Why boost::format cannot be converted directly to std::string? [closed]
Following is not possible:
std::string s = boost::format("%d") % 1; // error
You have to explicitely call the method str():
std::string s = (boost::format("%d") % 1).str(); // OK
It would only be ...
- 3,713
0
votes
2
answers
1k
views
VC++ 2012 and Boost incompatibility - `throw()` specifications in library headers
I have a new project where I cannot use boost::format. I get a compiler error complaining that boost's override of a virtual function, ~basic_altstringbuf, lacks a "throw()". Even the most trivial ...
- 17k
10
votes
4
answers
2k
views
boost::format and custom printing a std containers
I have a function in my namespace ns that helps me print STL containers. For example:
template <typename T>
std::ostream& operator<<(std::ostream& stream, const std::set<T>&...
- 27.6k
7
votes
1
answer
13k
views
Using %s format specifier with boost::format and std::string
I know that using the %s format specifier and std::string like this leads to undefined behaviour:
std::string myString = "test";
printf("%s", myString);
But is it save to use the same specifier and ...
- 1,427
0
votes
1
answer
256
views
How do you use a CAtlStringW with boost format?
I tried this:
#include <iostream>
#include <boost\format.hpp>
#include <atlstr.h>
std::ostream& operator<<(std::ostream& os, const ATL::CAtlStringW& string)
{
...
- 60.2k
1
vote
1
answer
121
views
How to cumulate time durations
I am using boost::format variable to get elapsed time in seconds
boost::posix_time::time_duration total_time = start_1.elapsed();
long milliseconds = total_time.total_milliseconds();
boost::format ...
- 2,493
7
votes
1
answer
1k
views
Is it possible to use Boost.Format with a preallocated buffer?
I was wondering whether Boost.Format does support using a fixed-width / preallocated buffer as output instead of a dynamic buffer managed by the lib itself?
That is, normally you'd do:
boost::...
- 38.7k
3
votes
6
answers
752
views
Real positional string formatting?
(Note: I know of Boost.Format, I'm looking for a better way to do the following.)
First a use-case example: In some countries, you name a person by calling his / her surname first and the forename ...
- 132k
4
votes
2
answers
2k
views
Using boost::format %s specifier with UTF-8 strings
We are adding support for UTF8 to an existing application with a large code base. This application uses boost::format(), and the output in non-ASCII characters is not aligning properly. Specifically,...
- 41
1
vote
1
answer
735
views
boost::format() output operator
I need to write the class which will accept boost::format() through the operator like cout does:
cout << boost::format("some string; some param = %d\n") % someValue;
Which type of operator's ...
- 2,226
5
votes
2
answers
606
views
Using boost::format in a boost::lambda
For some reason, I fail to use boost::format in a boost::lambda. Here is a (hopefully) compilable simplification of my code :
#include <algorithm>
#include <iomanip>
#include <iostream&...
- 76.7k