Arrays and Vectors

Difference: Vectors variable length whilst Arrays are fixed.

Arrays

std::array<T, num>

• num is the number of elements
• elements lie contiguously in memory
• size()
• a[1] is not bound checked
• a.at(1) is bound checked
  • std::out_of_range
• has iterators

C Style Arrays

For backwards compatibility, c style arrays exist, but are not upgraded.

int a[10] = {};
float b[3] = {0.1, 0.2, 0.3}

Vectors

std::vector<T>

• dynamically sized lists
• guaranteed to be contiguous
• additional functions
  • push_back --> Append
  • clear --> clear all contents
  • resize --> resize vector

Additional Loops

for(optional_init; auto i : container_with_iterator)

e.g.

for(std::vector<int> a{1,2,3,4,5,6,7}; auto i : a){
    std::cout << i << ", ";
}

The optional init is only executed once, and a will only be valid for the for loops scope.

for(std::vector<int> a{1,2,3,4,5,6,7}; auto i : a){
    std::cout << i << ", ";
}
a[1] = 5; // ERROR