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string-formattingchapel

How do I format strings output in Chapel?

When I'm printing numbers with Chapel's Formatted I/O I can set the length of numbers with something like

writeln("my number is %{#.###}", 3.14159)

I want to something similar with strings, but I don't see an example on the page. Basically, I'd like the string to line up in nice columns.

Solution

  • Your example is confusing writeln with writef. To use formatted IO in writeln, you'll need to invoke the .format() method. Here is an example that demonstrates the string format specifier (%s) and the generic format specifier (%t). These are listed on the page you've linked in the question.

    config var someString = 'ben';

// String format specifier
writeln('%s is great'.format(someString));
writef('%s is awesome\n', someString);


// Generic format specifier invokes the readThis / writeThis of the object
writeln('%t is awesome x%t'.format(someString, 2));

    Output:

    ben is great
ben is awesome
"ben" is awesome x2

    Note that string objects include quotes in their writeThis method, so you get quotes when using a string with the generic format specifier.