cppcontainers (version 1.0.4)

at: Access elements with bounds checking

Description

Read a value at a certain position with bounds checking.

Usage

at(x, position)

Value

Returns the value at the position.

Arguments

x

A CppMap, CppUnorderedMap, CppVector, or CppDeque object.

position

A key (CppMap, CppUnorderedMap) or index (CppVector, CppDeque).

Details

In the two associative container types (CppMap, CppUnorderedMap), [] accesses a value by its key. If the key does not exist, the function throws an error.

In the two sequence container types (CppVector, CppDeque), [] accesses a value by its index. If the index is outside the container, this throws an error.

at and [] both access elements. Unlike [], at checks the bounds of the container and throws an error, if the element does not exist.

See Also

[, back, contains, front, top.

Examples

m <- cpp_map(4:6, seq.int(0, 1, by = 0.5))
m
# [4,0] [5,0.5] [6,1]

at(m, 4L)
# [1] 0

d <- cpp_deque(c("hello", "world"))
d
# "hello" "world"

at(d, 2)
# [1] "world"