cpp/cs104/classes/ctor-init-list2 Source

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Description
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Build on your previous exercise to see NOT using the initialization list will be inefficient
calling the default constructor and then the operator=

</ol>
Learning goal: 
<ul><li>You should take advantage of the constructor initialization list.</li>
</ul>
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Copied from problem cpp/cs104/classes/ctor-initialization-list (author: redekopp@usc.edu)
Copied from problem cpp/cs104/classes/ctor-dtor-members (author: redekopp@usc.edu)
Copied from problem cpp/cs104/classes/ctor-default (author: redekopp@usc.edu)
Copied from problem cpp/cs104/classes/constructor_init (author: redekopp@usc.edu)

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Engine
Choices
json list of string, bool pairs
e.g. [["good", true], ["bad", false]]

Correct answer
Template / Reference solution

Template / Reference solution

#include <iostream>
#include <algorithm>
using namespace std;

struct A1 {
\[
REDACTED
\show:
A1() {
cout << "A1 default ctor" << endl;
for(double i = 0; i < 10; i += 0.2) { x += i; }
}
A1(double myx) { cout << "Init A1 ctor" << endl; x = myx; }
A1& operator=(const A1& other)
{ cout << "A1 operator=" << endl; x = other.x; return *this; }
double x;
]\
};

class A2 {
public:
\[
REDACTED
\show:
A2() : m1(0), m2(0) { cout << "Default A2 ctor" << endl;}
A2(const A1& mym1, const A1& mym2) {
cout << "Init A2 ctor" << endl;
m1 = mym1;
m2 = mym2;
}
]\
void print() const { cout << "m1=" << m1.x << " m2=" << m2.x << endl;}
private:
A1 m1;
A1 m2;
};
int main()
{
\[
REDACTED
\show:
A1 mym1(3.8); A1 mym2(3.95);
A2 obj1(mym1, mym2);
obj1.print();
]\
return 0;
}

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to just run once with no input use [{}]

[{}]
C++ test suite
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Property	Value
Description html markup shown to student	Build on your previous exercise to see <strong>NOT</strong> using the initialization list will be inefficient calling the <strong>default constructor</strong> and then the <strong>operator=</strong> </ol> <p><strong>Learning goal:</strong> </p> <ul><li>You should take advantage of the constructor initialization list.</strong></li> </ul>
Epilogue html markup shown when solved	remove
Public permissions	remove
Remarks Comments, history, license, etc.	Copied from problem cpp/cs104/classes/ctor-initialization-list (author: redekopp@usc.edu) Copied from problem cpp/cs104/classes/ctor-dtor-members (author: redekopp@usc.edu) Copied from problem cpp/cs104/classes/ctor-default (author: redekopp@usc.edu) Copied from problem cpp/cs104/classes/constructor_init (author: redekopp@usc.edu) remove
Engine
Choices json list of string, bool pairs e.g. `[["good", true], ["bad", false]]`
Correct answer
Template / Reference solution
Template / Reference solution	#include <iostream> #include <algorithm> using namespace std; struct A1 { \[ REDACTED \show: A1() { cout << "A1 default ctor" << endl; for(double i = 0; i < 10; i += 0.2) { x += i; } } A1(double myx) { cout << "Init A1 ctor" << endl; x = myx; } A1& operator=(const A1& other) { cout << "A1 operator=" << endl; x = other.x; return *this; } double x; ]\ }; class A2 { public: \[ REDACTED \show: A2() : m1(0), m2(0) { cout << "Default A2 ctor" << endl;} A2(const A1& mym1, const A1& mym2) { cout << "Init A2 ctor" << endl; m1 = mym1; m2 = mym2; } ]\ void print() const { cout << "m1=" << m1.x << " m2=" << m2.x << endl;} private: A1 m1; A1 m2; }; int main() { \[ REDACTED \show: A1 mym1(3.8); A1 mym2(3.95); A2 obj1(mym1, mym2); obj1.print(); ]\ return 0; }
Java test suite See manual
C++ test suite json list of stdin/args tests e.g. `[{"stdin":"hi", "args":["4", "5"]}, {"stdin":"noargs"}]` to just run once with no input use `[{}]`	[{}]
C++ test suite See manual
Forbidden substrings json list of strings e.g. `["for","while"]`	remove
Solution visibility	remove
Java imports json list of importables e.g. `["java.util.*"]`	remove
Override Java classname else defaults to websheet name	remove
Dependent on other websheets? json list of websheet names in this folder e.g. `["DataStructure"]`	remove
Is example? i.e., just a demo	remove
Add compiler flag(s) json list of flags e.g. `["-Wno-unused-variable"]`	remove
Remove default compiler flag(s) json list of flags see default_cppflags e.g. `["-Wno-write-strings"]`	remove

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