format

简介

CPP库: fmt

格式化语法: Format String Syntax

注意: pkg只封装了fmt中core.h的format接口，无法使用一些特殊的格式：如 计时规格 等

基本用法：

string result = format.format("Hello {}\n", "world"); // Hello world
format.print("Hello {}\n", "world"); // Hello world

更新

v1.1.0 支持了首字母大写、大小写转换功能：

format.format("Hello {0:c}\n", "world"); // Hello World
format.print("{:c}\n", "hello World"); // Hello World
format.format("Hello {0:u}\n", "world"); // Hello WORLD
format.format("Hello {0:l}\n", "world"); // Hello world

组件接口

format.gs

函数原型	函数作用
string format(string fmt, ...)	根据指定的格式将对象的值转换为字符串并插入到相应位置
void print(string fmt, ...)	直接打印结果

样例

// Accessing arguments by position:
write(format.format("{0}, {1}, {2}\n", "a", "b", 10));
// Result: "a, b, c"
write(format.format("{}, {}, {}\n", "a", "b", "c"));
// Result: "a, b, c"
write(format.format("{2}, {1}, {0}\n", "a", "b", "c"));
// Result: "c, b, a"
write(format.format("{0}{1}{0}\n\n", "abra", "cad"));  // arguments' indices can be repeated
// Result: "abracadabra"

// Aligning the text and specifying a width:
write(format.format("{:<30}\n", "left aligned"));
// Result: "left aligned                  "
write(format.format("{:>30}\n", "right aligned"));
// Result: "                 right aligned"
write(format.format("{:^30}\n", "centered"));
// Result: "           centered           "
write(format.format("{:*^30}\n\n", "centered"));  // use '*' as a fill char
// Result: "***********centered***********"

// Dynamic width:
write(format.format("{:<{}}\n\n", "left aligned", 30));
// Result: "left aligned  

// begin @ format
// Dynamic precision:
write(format.format("{:.{}f}\n\n", 3.14, 1));
// Result: "3.1"

// Dynamic precision:
write(format.format("{:.{}f}\n\n", 3.14, 1));
// Result: "3.1"

// Replacing %+f, %-f, and % f and specifying a sign:
write(format.format("{:+f}; {:+f}\n", 3.14, -3.14));  // show it always
// Result: "+3.140000; -3.140000"
write(format.format("{: f}; {: f}\n", 3.14, -3.14));  // show a space for positive numbers
// Result: " 3.140000; -3.140000"
write(format.format("{:-f}; {:-f}\n\n", 3.14, -3.14));  // show only the minus -- same as '{:f}; {:f}'
// Result: "3.140000; -3.140000"

// Replacing %x and %o and converting the value to different bases:
write(format.format("int: {0:d};  hex: {0:x};  oct: {0:o}; bin: {0:b}\n", 42));
// Result: "int: 42;  hex: 2a;  oct: 52; bin: 101010"
// with 0x or 0 or 0b as prefix:
write(format.format("int: {0:d};  hex: {0:#x};  oct: {0:#o};  bin: {0:#b}\n\n", 42));
// Result: "int: 42;  hex: 0x2a;  oct: 052;  bin: 0b101010"

// Padded hex byte with prefix and always prints both hex characters:
write(format.format("{:#04x}\n\n", 0));
// Result: "0x00"

// Box drawing using Unicode fill:
format.print(
  "┌{0:─^{2}}┐\n"
  "│{1: ^{2}}│\n"
  "└{0:─^{2}}┘\n\n", "", "Hello, world!", 20);
// Result:
// ┌────────────────────┐
// │   Hello, world!    │
// └────────────────────┘

// :c :u :l
write(format.format("Hello {0:c}\n", "world"));

format.print("{:c}\n", "hello World");

format.print("Hello {0:u}\n", "world");
format.print("Hello {0:l}\n", "WORLD");