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Clojure: Форматирование строк

В программировании часто возникает задача собрать строку из значений, которые не являются строками сами по себе. Для решения подобных задач применяют форматирование (formatting) строк (оно же — "строковая интерполяция"). В Clojure рассмотрим самые популярные

Функции format и printf

Функции format и printf ожидают в качестве первого аргумента строку-шаблон и несколько значений, которые будут в этот шаблон подставлены. Разница же между функциями в том, что вызов format вычисляется в строку, а printf сразу выводит значение на экран (результатом же вычисления будет nil).
Шаблон может содержать произвольный текст, в нужные места которого вставлены последовательности (подробности в классе java.util.Formatter).
Вот несколько примеров применения format:

(format "Hello there, %s" "bob")
; => "Hello there, bob"
(format "%5d" 3)
; => "    3"
(format "Pad with leading zeros %07d" 5432)
; => "Pad with leading zeros 0005432"
(format "Left justified :%-7d:" 5432)
; => "Left justified :5432   :"
(format "decimal %d  octal %o  hex %x  upper-case hex %X" 63 63 63 63)
; => "decimal 63  octal 77  hex 3f  upper-case hex 3F"
(format "%.3f" 2.0)
; => "2.000"
(format "%.3f" (double (/ 5 2)))
; => "2.500"


Реализуйте функцию number-presenter, которая представляет число в нескольких форматах.

(number-presenter 63)
; => "decimal 63  octal 77  hex 3f  upper-case hex 3F"
(number-presenter 14)
; => "decimal 14  octal 16  hex e  upper-case hex E"
The exercise doesn't pass checking. What to do? 😶

If you've reached a deadlock it's time to ask your question in the «Discussions». How ask a question correctly:

  • Be sure to attach the test output, without it it's almost impossible to figure out what went wrong, even if you show your code. It's complicated for developers to execute code in their heads, but having a mistake before their eyes most probably will be helpful.
In my environment the code works, but not here 🤨

Tests are designed so that they test the solution in different ways and against different data. Often the solution works with one kind of input data but doesn't work with others. Check the «Tests» tab to figure this out, you can find hints at the error output.

My code is different from the teacher's one 🤔

It's fine. 🙆 One task in programming can be solved in many different ways. If your code passed all tests, it complies with the task conditions.

In some rare cases, the solution may be adjusted to the tests, but this can be seen immediately.

I've read the lessons but nothing is clear 🙄

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