Len()
len() is a built-in operation that returns the number of elements, items, characters, bytes, or other units in a supported value.
A Pythonic Adventure: From Python basics to a working web app
The Python len function returns the number of items in a container or characters in a string.
- How it is used
- Uses len() to size a menu divider automatically and to inspect strings or lists during quick REPL experiments.
- How deep it goes
- Defines len() through interactive string and list examples, then applies it in a function without covering implementation internals.
- Examples
- Demonstrates len('abcd'), len('hello'), len([1, 2, 3]), and a title-sized divider in a coffee-shop menu.
- What you can do after
- Apply it via Python to measure strings or lists and generate automatically sized menu dividers.
Read how A Pythonic Adventure: From Python basics to a working web app explains len() →
Go in Action, Second Edition
len is a Go built-in function that returns the number of bytes in a string or the number of elements in a supported collection.
- How it is used
- Measures sizes for counting and iteration, and guards indexed access to slices such as command-line arguments.
- How deep it goes
- Defines length for collections and strings, works through panic prevention and UTF-8 byte counts, but defers detailed encoding mechanics.
- Examples
- Uses a three-medalist slice that can panic and a two-character Unicode string whose length is six bytes.
- What you can do after
- Diagnose/debug with it to prevent out-of-range access and distinguish UTF-8 byte counts from visible character counts.
Get Programming: Learn to code with Python
len is a Python built-in function that returns the number of items in an object, including the number of characters in a string.
- How it is used
- Uses len() to count characters or elements while teaching strings, tuples, and lists.
- How deep it goes
- Defines len() with worked string, tuple, and list examples, then connects list length to indexing limits.
- Examples
- Uses an essay character limit, sample strings, nested tuples, grocery lists, and tuple-length quick checks.
- What you can do after
- Apply it to calculate sequence sizes and identify valid list index positions.
Read how Get Programming: Learn to code with Python explains len() →
Related concepts
- stringmeasures · A string is a programming-language value representing an ordered sequence of characters or character units as text.
- listmeasures · A list is an ordered collection of elements arranged in a sequence.
- slicinguses · Slicing selects or partitions a portion of an indexed sequence or multidimensional array, often along specified indices or dimensions.
- Mapmeasures · A map is an associative data structure that stores key-value pairs and supports retrieving values by key.
- empty slicemeasures · An empty slice is a Go slice whose length is zero, regardless of whether it has a nil descriptor or allocated backing storage.
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