formattedWrite

Converts its arguments according to a format string and writes the result to an output range.

The second version of formattedWrite takes the format string as a template argument. In this case, it is checked for consistency at compile-time.

  1. uint formattedWrite(Writer w, Char[] fmt, Args args)
  2. uint formattedWrite(Writer w, Args args)
    uint
    formattedWrite
    (
    alias fmt
    Writer
    Args...
    )
    (
    auto ref Writer w
    ,
    Args args
    )

Parameters

w Writer

an output range, where the formatted result is written to

fmt
args Args

a variadic list of arguments to be formatted

Writer

the type of the writer w

Args

a variadic list of types of the arguments

Return Value

Type: uint

The index of the last argument that was formatted. If no positional arguments are used, this is the number of arguments that where formatted.

Throws

A FormatException if formatting did not succeed.

Note: In theory this function should be @nogc. But with the current implementation there are some cases where allocations occur. See $(D sformat) for more details.

Examples

The format string can be checked at compile-time:

import std.array : appender;

auto writer = appender!string();
writer.formattedWrite!"%d is the ultimate %s."(42, "answer");
assert(writer[] == "42 is the ultimate answer.");

// This line doesn't compile, because 3.14 cannot be formatted with %d:
// writer.formattedWrite!"%d is the ultimate %s."(3.14, "answer");
import std.array : appender;

auto writer1 = appender!string();
formattedWrite(writer1, "%s is the ultimate %s.", 42, "answer");
assert(writer1[] == "42 is the ultimate answer.");

auto writer2 = appender!string();
formattedWrite(writer2, "Increase: %7.2f %%", 17.4285);
assert(writer2[] == "Increase:   17.43 %");

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