An object of type std::array can be passed to a function just like any other object. That means if we pass a std::array by value, an expensive copy will be made. Therefore, we typically pass std::array by (const) reference to avoid such copies. With a std::array, both the element type …
In lesson , we discussed the unfortunate decision to make the standard library container classes use unsigned values for lengths and indices. Because std::array is a standard library container class, it is subject to the same issues. In this lesson, we’ll recap ways to index and get the length of …
Words of encouragement This chapter isn’t an easy one. We covered a lot of material, and unearthed some of C++’s warts. Congrats on making it through! Arrays are one of the keys that unlock a huge amount of power within your C++ programs. Chapter Review A container is a data …
In lesson , we discussed how std::bitset has the capability to compact 8 Boolean values into a byte. Those bits can then be modified via the member functions of std::bitset. std::vector has an interesting trick up its sleeves. There is a special implementation for std::vector<bool> that may be more space …
Consider the case where you are writing a program where the user will enter a list of values (such as a bunch of test scores). In this case, the number of values that they will be entering is not known at compile time, and could vary every time they run …
One of the bigger documentation problems with arrays is that integer indices do not provide any information to the programmer about the meaning of the index. Consider an array holding 5 test scores: #include <vector> int main() { std::vector testScores { 78, 94, 66, 77, 14 }; testScores[2] = 76; …
In lesson , we noted how we generally prefer to use signed values to hold quantities, because unsigned values can act in surprising ways. However, in lesson , we discussed how std::vector (and other container classes) uses unsigned integral type std::size_t for length and indices. This can lead to problems …
In the prior lesson , we introduced operator[], which can be used to subscript an array to access an element. In this lesson, we’ll look at other ways to access array elements, as well as a few different ways to get the length of an container class (the number of …
An object of type std::vector can be passed to a function just like any other object. That means if we pass a std::vector by value, an expensive copy will be made. Therefore, we typically pass std::vector by (const) reference to avoid such copies. With a std::vector, the element type is …
The variable scalability challenge Consider a scenario where we want to record the test scores for 30 students and calculate the average score for the class. To do so, we’ll need 30 variables. We could define those like this: // allocate 30 integer variables (each with a different name) int …
