C++
Putting it together
Combine helper functions into a single class.
Putting it together
In the final lesson we bring the three helpers together: capitalize, clamp and formatDate. The previous lessons' solution is now ready inside the Helpers class. We will call all three in main and print their results.
This lesson's starting code contains all the methods from the previous lesson. All you need to do is add three calls inside main. This shows how the library is used. Output: Hello, 10, 2024-03-15 — each on a separate line.
Using the helpers together
We call the three helpers one after another in main. We separate each call with std::endl to show the output on separate lines. Helpers::capitalize("hello") returns a string, Helpers::clamp(15, 0, 10) a number, Helpers::formatDate(2024, 3, 15) a string again.
Despite three different return types, std::cout prints all of them. This is the flexibility of C++'s stream architecture. To extend the library, you just add a new static method to the Helpers class; you do not need to change existing code.
Exercise Call all three helpers
In main call all three helpers: std::cout << Helpers::capitalize("hello") << std::endl;, std::cout << Helpers::clamp(15, 0, 10) << std::endl; and std::cout << Helpers::formatDate(2024, 3, 15);. Each output on a separate line.
Show example solution
#include <iostream>
#include <string>
#include <cctype>
class Helpers {
public:
static std::string capitalize(std::string text) {
if (text.empty()) return text;
text[0] = std::toupper(text[0]);
return text;
}
static int clamp(int value, int min, int max) {
if (value < min) return min;
if (value > max) return max;
return value;
}
static std::string formatDate(int year, int month, int day) {
std::string m = std::to_string(month);
if (m.length() == 1) m = "0" + m;
std::string d = std::to_string(day);
if (d.length() == 1) d = "0" + d;
return std::to_string(year) + "-" + m + "-" + d;
}
};
int main() {
std::cout << Helpers::capitalize("hello") << std::endl;
std::cout << Helpers::clamp(15, 0, 10) << std::endl;
std::cout << Helpers::formatDate(2024, 3, 15);
return 0;
}
Library complete
Congratulations! You completed the 5-lesson helper library project. The Helpers class now has three useful static methods: capitalize, clamp and formatDate. Each does a specific job and is called with the Helpers:: prefix.
Throughout this project you practiced class design, static methods, member functions and a cumulative code structure. In the next section we will deepen encapsulation: private members, const methods, mutable and friend to protect data more tightly.
Test yourself
-
Why is a helper library gathered in one class?
class Helpers { public: static ... };
- To avoid name clashes and ease use
- To save memory
- To run faster
- The compiler requires it
Show answer
To avoid name clashes and ease use — One class acts like a namespace and makes use easier.
-
Complete the capitalize call
std::cout << ____::capitalize("hello");
Show answer
std::cout << Helpers::capitalize("hello");
Next lesson: private members
