fmt - McMap

1

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How to correctly use named args in C++ Fmt library

I have the following bit of code, that uses a runtime determined width: #include <string> #include <vector> #include <fmt/core.h> #include <fmt/format.h> int main() { std...

c++c++20 fmt

Epaminondas asked 1/9 at 5:5

1

Solved

Why does std::format() throw at runtime for incorrect format specifiers?

Recently I discovered that the following code compiles on a few major compilers, and then throws at runtime: std::cout << std::format("{:*<{}}", 10, "Hello") << s...

c++fmt

Deipnosophist asked 9/2 at 20:19

3

Solved

Format no such file or directory

I was trying to use the C++ format utility (std::format). I tried to compile this simple program: #include <format> int main() { std::cout << std::format("{}, {}", "Hel...

c++gcc fmt

Tull asked 1/12, 2020 at 1:33

1

Solved

Why does std::println(std::vector) fail to compile?

I have the following code: #include <print> #include <vector> int main() { std::vector<int> v{1, 2, 3}; std::println("{}", v); } Among the numerous errors this produ...

c++stdvector libc++fmt c++23

Rage asked 4/1 at 0:44

1

How do I check at compile-time if there's enough `{}` placeholders for all arguments?

std::format has a (compile-time and runtime) format string validation, but one thing not included in this validation is whether there are enough {} placeholders for all arguments (excessive argumen...

c++fmt stdformat

Archoplasm asked 7/12, 2023 at 5:52

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How do I use std::formatter directly?

Let's say I want to format a single object directly using std::formatter, bypassing std::format. How do I do that? According to Formatter, I need to call .format(value, format_ctx), where format_ct...

c++fmt stdformat

Hartsfield asked 16/11, 2023 at 5:47

2

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fmt format %H:%M:%S without decimals

I am trying to format a std::chrono::duration object to the format HH:MM::SS, e.g. 16:42:02 being the hours (16), the minutes (42), and the seconds (2). the library fmt offers useful formatting spe...

c++formatting c++20 c++-chrono fmt

Glittery asked 10/11, 2023 at 17:13

2

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Does GCC support C++23 std::print?

On CppCon 2022 was announced, that new official HelloWorld in C++ is now: #include <print> int main() { std::print("Hello world\n"); return 0; } Do you know, is std::print avail...

c++gcc std fmt c++23

Malefactor asked 24/8, 2023 at 7:49

5

Solved

C++ namespace "std" has no member "format" despite #include <format>

I am new to C++. I am trying to store the current date and time as a string variable. At this question, I found an answer, and installed the date.h library. However, when I try to use the code prov...

c++visual-studio-2022 fmt

Foch asked 3/12, 2021 at 2:52

2

Solved

std::format %z specifier not working for local_time

I want to get a timestamp in the format "YYYY-MM-DD hh::mm::ss.fff +zz". I thought I could do this with the %z specifier for std::format but I'm getting this error on MSVC: error C7595: '...

c++c++20 fmt

Over asked 23/6, 2023 at 18:22

1

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Displaying steady_clock::now() using fmt library

I'm able to display the current time using C++ fmt library using std::chrono::system_clock and std::chrono::high_resolution_clock but unable to display time using std::chrono::steady_clock. Here is...

c++c++11 c++-chrono fmt

Botryoidal asked 25/2, 2023 at 11:18

3

C++ 23 Does std::print or std::println flush the output stream?

Prior to C++ 23, when using std::cout to send output to stdout, there is a distinction between the following two ways of adding a new line at the end of the printed string: std::cout << &quo...

c++stl fmt c++23

Kellby asked 22/2, 2023 at 21:0

3

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How can I avoid using #define macros in C++ in a case where I have to concatenate two const char* variables?

I would like to remove the reliance of #define macros in my code, and I'm unable to achieve the same functionality with constexpr. To be practical, consider the following example: #define PRODUCT_N...

c++c++20 constexpr fmt string-view

Planetary asked 24/1, 2023 at 2:3

1

Code using fmt::format breaks after Visual Studio 2022 Update 17.4

I am using fmt::format from the fmtlib extensively. After updating Visual Studio 2022 from 17.3.5 to 17.4.0 I have a problem in Release Builds with Code like the following: const std::string s1 = f...

c++visual-studio-2022 fmt

Adrienneadrift asked 11/11, 2022 at 13:12

5

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Does GCC support C++20 std::format?

If it doesn't, do you know what compiler or version will? See cppreference/format.

c++gcc stl c++20 fmt

Shifflett asked 3/9, 2020 at 12:50

3

Solved

eigen3 with libfmt >= 9.0

I used to be able to pass Eigen3 arrays/matrices to spdlog, which internally uses libfmt. Starting with libfmt 9.0.0, these types are no longer formatted by libfmt without further code. Custom type...

eigen eigen3 fmt

Jericajericho asked 16/9, 2022 at 18:18

1

Solved

Does fmt library handle printing std::chrono::time_point?

An earlier version of the documentation for the C++ {fmt} libary said, about the "chrono format specifiers": Specifiers that have a calendaric component such as 'd' (the day of month) ar...

c++c++-chrono fmt

Agbogla asked 9/9, 2022 at 3:31

1

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How to use std::format to format all derived class of the same base class?

I have lots of classes derived from the same base class, and I'm trying to avoid writing a formatter for all derived classes. I tried to only implement the std::formatter for the base class, but pa...

c++formatting c++20 fmt

Silurian asked 22/6, 2022 at 5:58

3

Solved

How do I print a vector of chars using fmt?

I have a const std::vector<char> - not null-terminated. I want to print it using the fmt library, without making a copy of the vector. I would have hoped that specifying the precision would s...

c++c++14 std null-terminated fmt

Demibastion asked 5/6, 2022 at 20:18

4

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How to pass not variadic values to fmt::format?

I'm playing with the great fmt C++ library to format strings more gracefully. And I'd like to pass a non-variable arguments list to fmt::format. It could be a std::vector, or std::string, or whate...

c++formatting variadic-functions variadic fmt

Armin asked 19/2, 2018 at 23:2

2

Solved

Can't use std::format in c++20

I've been trying to use the std::format function included in C++20. As far as I can tell, clang 14 is supposed to support this feature, but for some reason I am receiving the following error: no me...

c++clang++fmt

Tushy asked 7/4, 2022 at 6:53

1

Solved

fmt Library - Formatting to a (compile-time) string_view

I would like to use the fmt library to create a string_view from my format args. There is plenty documented about passing in a compile-time string as the format string, however, I want to output a ...

c++string-formatting compile-time string-view fmt

Glove asked 22/2, 2022 at 13:25

1

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How to figure out the length of the result of `fmt::format` without running it?

While answering this question about printing a 2D array of strings into a table, I realized: I haven't found a better way to determine the length of the result of a fmt::format call that to actuall...

c++fmt

Conners asked 8/12, 2021 at 18:40

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Prevent fmt from printing function pointers

I have a following buggy program. Logic is nonsense, it is just a toy example. #include <ranges> #include <iostream> #include <fmt/format.h> #include <fmt/ranges.h> templat...

c++c++20 fmt

Antonomasia asked 22/11, 2021 at 16:29

2

Solved

How to create a function that forwards its arguments to fmt::format keeping the type-safeness?

I have two broadly related questions. I want to make a function that forwards the arguments to fmt::format (and later to std::format, when the support increases). Something like this: #include <...

c++c++20 fmt

Perihelion asked 6/8, 2021 at 2:8

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