Contributed by Alex1957open in new window

DynamicVector

import

from Vector import DynamicVector

init

You can reserve memory to add elements without the cost of copying everything if it grows too large.

Reserve 8 elements worth of memory:

var vec = DynamicVector[Int](8)

push_back

To add elements to the vector, you can use the push_back method:

vec.push_back(10)
vec.push_back(20)

print(len(vec))

variables

print(vec.capacity)
print(vec.data[0])
print(vec.size)

8
10
2

indexing

You can access and assign elements using indexes

WARNING

No bounds checking, can access garbage data

print(vec[0])

vec[1] = 42
print(vec[1])

WARNING

Setting elements this way won't increase the len so may lead to errors, you should only use push_back to add a new element, and use this to modify existing elements

print(len(vec))
vec[6] = 10
print(len(vec))

2
2
10

copying

This will result in a shallow copy, it'll be a pointer to the same location in memory:

var vec2 = vec

If we modify vec then vec2 will also be updated:

vec[0] = 99
print(vec2[0])

Use deep copy to copy all the data to a different location in memory so it's independent from the original:

var vec3 = vec.deepcopy()

Modifying the original now won't effect the new copy:

vec[1] = 100
print(vec3[1])

pop_back

Access the last element, deallocate it, and reduce the element size by 1:

WARNING

This will access garbage data if there are no elements left

print(vec.pop_back())

reserve

If it's greater than the current capacity then data is reallocated and moved:

vec.reserve(16)
print(vec.capacity)

resize

Discard elements if smaller then current size, add uninitialized data if larger:

vec.resize(16)
print(vec.size)

clear

Deallocates the data in the vector

vec.clear()
print(vec[1])