last_index_of

Builtin index · Collections & strings

result = last_index_of(s, sub)

Input: s, sub · Output: result

What it is

s and sub are Strs.

Overloads

One call shape — this function is not overloaded.

Code	Input	Output	Description
`result = last_index_of(s, sub)`	`s` Strnot documented yet `sub` Strnot documented yet	`number` —0-based character position of the last occurrence, searching from the end	Returns a `number` (0-based character position of the last occurrence, searching from the end) or `none` if absent — so a miss cannot be mistaken for a position.

Examples

From the documentation, and run by the build -- the output and the figure below are what the engine actually produced. Simplest first.

path = "report_final_v2.txt"
print(ends_with(path, ".txt"))         # true

print(index_of(path, "_"))              # 6

print(last_index_of(path, "_"))         # 12

print(insert("helloworld", 5, ", "))    # "hello, world"

print(remove("hello, world", ", "))     # "helloworld"

line = "key: value"
print(after(line, ": "))                # "value"

print(before(line, ": "))               # "key"

full = "a/b/c.txt"
print(after_last(full, "/"))            # "c.txt"

print(before_last(full, "/"))           # "a/b"

output

true
6
12
hello, world
helloworld
value
key
c.txt
a/b

from collections-strings

How it works

last_index_of(s, sub) — like index_of from the other end, and like it returns none rather than -1 when absent, so a missing result cannot be mistaken for a position.

From the note above this builtin in the interpreter, where the reasoning was written down as it was built.