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fmtlib

fmtlib

编译

git clone https://github.com/fmtlib/fmt.git fmt
# 选择tag 8.1.1
cd fmt & git tag & git checkout -b 8.1.1 
mkdir debug & cd debug
cake .. & make -j
# 编译完毕后，生成“libfmt.a”静态库

使用

将"include/fmt/format.h, include/fmt/core.h, debug/libfmt.a"拷贝到需要使用的目录，如"third/fmt/"

在头文件中，增加

#include <fmt/format.h>
#include <fmt/core.h>

fmt语法

格式语法: Format String Syntax

replacement_field ::=  "{" [arg_id] [":" (format_spec | chrono_format_spec)] "}"
arg_id            ::=  integer | identifier
integer           ::=  digit+
digit             ::=  "0"..."9"
identifier        ::=  id_start id_continue*
id_start          ::=  "a"..."z" | "A"..."Z" | "_"
id_continue       ::=  id_start | digit

# 
format_spec ::=  [[fill]align][sign]["#"]["0"][width]["." precision]["L"][type]
fill        ::=  <a character other than '{' or '}'>
align       ::=  "<" | ">" | "^"
sign        ::=  "+" | "-" | " "
width       ::=  integer | "{" [arg_id] "}"
precision   ::=  integer | "{" [arg_id] "}"
type        ::=  "a" | "A" | "b" | "B" | "c" | "d" | "e" | "E" | "f" | "F" | "g" |
                 "G" | "o" | "p" | "s" | "x" | "X"

#
chrono_format_spec ::=  [[fill]align][width]["." precision][chrono_specs]
chrono_specs       ::=  [chrono_specs] conversion_spec | chrono_specs literal_char
conversion_spec    ::=  "%" [modifier] chrono_type
literal_char       ::=  <a character other than '{', '}' or '%'>
modifier           ::=  "E" | "O"
chrono_type        ::=  "a" | "A" | "b" | "B" | "c" | "C" | "d" | "D" | "e" | "F" |
                        "g" | "G" | "h" | "H" | "I" | "j" | "m" | "M" | "n" | "p" |
                        "q" | "Q" | "r" | "R" | "S" | "t" | "T" | "u" | "U" | "V" |
                        "w" | "W" | "x" | "X" | "y" | "Y" | "z" | "Z" | "%"

https://hackingcpp.com/cpp/libs/fmt.html

基础用法示例

#include <fmt/core.h>
#include <fmt/format.h>
#include <fmt/color.h>

using namespace fmt::literals;

// (1) 结果为: "The answer is 4"
fmt::print(stdout, "The answer is {} \n", 4);

// (2) 结果为: "string:ABC, char:F, Int:8, Double:5.12"
fmt::print(stdout, "string:{}, char:{}, Int:{}, Double:{} \n", "ABC", 'F', 8, 5.12);

// (3) 使用索引，从0开始
//     结果为: "ABC Hello ABC"
fmt::print("{1} {0} {1} \n", "Hello", "ABC");

// (4) 使用命名的{}来格式化, 需要 “using namespace fmt::literals;”
//     结果为"SSE:600008"
fmt::print("{exchange}:{code} \n", "exchange"_a = "SSE", "code"_a = "600008");

// (5) 需要长度的格式化
//     结果为"price:   6.236"
fmt::print("price:{:>8.3f} \n", 6.235689); // 右对齐，保留3位小数，总长度为8

// (6) 对齐
fmt::print("{:>10}", 245); // 右对齐，长度为10
fmt::print("{:<10}", 245); // 左对齐
fmt::print("{:*^10}", 245); // 中间对齐，用*填充

// (7) 颜色, fmt::rgb
fmt::print(fg(fmt::color::steel_blue) | fmt::emphasis::italic, "{}.\n", 42);
fmt::print(fg(fmt::rgb(100, 28, 36)) | fmt::emphasis::italic, "{}.\n", 42);

// (8) 格式化字符串
fmt::memory_buffer buf;
fmt::format_to(buf, "hello {}! ", "world");
fmt::format_to(buf, "This is {}.", 42);
std::cout << buf.data() << std::endl;

// (9) pointer
const char *p = "abc";
fmt::print("{}", fmt::ptr(p));

// (10) print vector
std::vector<uint32_t> vec(1, 2, 4, 5);
fmt::print("{}", fmt::join(vec, ",")); // 1, 2, 4, 5