add a few new programs related to templates

i made new programs related to lambdas, and various things you can do
with templates like generic functions and overriding the () operator
meaning you can call a class object like a function.
This commit is contained in:
Fries 2023-06-25 18:11:41 -07:00
parent 3dcb5197cb
commit a4948ef410
4 changed files with 108 additions and 0 deletions

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@ -20,3 +20,6 @@ add_executable(vector vector.cc)
add_executable(Vector2 Vector2.cc)
add_executable(TemplateVector TemplateVector.cc)
add_executable(buffer buffer.cc)
add_executable(FunctionTemplates FunctionTemplates.cc)
add_executable(FunctionObjects FunctionObjects.cc)
add_executable(lambdas lambdas.cc)

54
src/FunctionObjects.cc Normal file
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@ -0,0 +1,54 @@
// you can override the () operator meaning you can call class objects like functions.
#include <format>
#include <iostream>
#include <string>
template <typename T>
class LessThan {
private:
const T val;
public:
LessThan(const T& v)
: val { v }
{
}
bool operator()(const T& x) const
{
return x < val;
}
};
template <typename T>
class GreaterThan {
private:
const T val;
public:
GreaterThan(const T& v)
: val { v }
{
}
bool operator()(const T& x) const
{
return x > val;
}
};
int main()
{
LessThan<int> i1(21);
LessThan<double> i2(21.420);
GreaterThan<int> i3(21);
GreaterThan<double> i4(21.420);
std::cout << std::format("less than 21: {}", i1(1)) << std::endl;
std::cout << std::format("less than 21.420: {}", i2(420.21)) << std::endl;
std::cout << std::format("greater than 21: {}", i3(1)) << std::endl;
std::cout << std::format("greater than 21.420: {}", i4(420.21)) << std::endl;
}

28
src/FunctionTemplates.cc Normal file
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@ -0,0 +1,28 @@
#include <format>
#include <iostream>
#include <string>
template <typename T>
T sum(const T& sum1, const T& sum2)
{
return sum1 + sum2;
}
void print_number(const std::string& stringName, const auto& value)
{
std::cout << std::format("{} = {}", stringName, value) << std::endl;
}
int main()
{
double i1 = sum(1.4, 1.2);
int i2 = sum(1, 1);
auto i3 = sum<int>(2, 2);
auto i4 = sum<double>(4.4, 4.2);
print_number("i1", i1);
print_number("i2", i2);
print_number("i3", i3);
print_number("i4", i4);
}

23
src/lambdas.cc Normal file
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@ -0,0 +1,23 @@
#include <format>
#include <iostream>
template <typename T>
bool less_than(const T& i)
{
return [&]() {
return i < 21;
}();
}
auto greater_than = [](const double i) {
return i > 21.420;
};
int main()
{
std::cout << std::format("less than 21 <lambda edition>: {}", less_than(20)) << std::endl;
std::cout << std::format("less than 21 <lambda edition>: {}", less_than(22)) << std::endl;;
std::cout << std::format("greater than 21 <lambda edition>: {}", less_than(22)) << std::endl;
std::cout << std::format("greater than 21 <lambda edition>: {}", less_than(20)) << std::endl;
}