On Thursday, 31 March 2016 at 03:15:49 UTC, cy wrote:
This might be a dumb question. How do I format a string so that
all the newlines print as \n and all the tabs as \t and such?
The easiest is this:
```d
import std.conv;
string str = `Hello "World"
line 2`;
writeln([str].text[2..$-2]); // Hello \"World\"\nline 2
```
I know this is an old post, but I felt this trick needed to be
shared.
This takes advantage of the fact that `std.format` escapes the
characters in an array of strings. So we create an array where
`str` is the only element, and convert that to text. Without the
`[2..$-2]` slicing the output would be `["Hello \"World\"\nline
2"]`.
A slightly more efficient implementation is
```d
string escape(string s)
{
import std.array : appender;
import std.format : FormatSpec, formatValue;
FormatSpec!char f;
auto w = appender!string;
w.reserve(s.length);
formatValue(w, [s], f);
return w[][2 .. $ - 2];
}
```
And the inverse:
```d
string unescape(string s)
{
import std.format : FormatSpec, unformatValue;
FormatSpec!char f;
string str = `["` ~ s ~ `"]`;
return unformatValue!(string[])(str, f)[0];
}
```
Perhaps `escape()` and `unescape()` should be part of
`std.format` so that they can be refactored to use
`std.format.internal.write.formatElement` directly, eliminating
the conversion to array.
-- Bastiaan.
