Homework 7 -- Classes

Section 1.7 Homework 7 -- Classes

Exercises Exercises

1.

The acronym "OOP" refers to...

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object-oriented programming
open object paradigm
output operator programming

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2.

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3.

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4.

It’s important that other programmers are able to use one of the classes you’ve created in C++ without knowing the details of how you implemented the class.

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True
False

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5.

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6.

The operator `::` (two colons) in C++ is called the...

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scope resolution operator
double colon operator
four dots operator
namespace specifier

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7.

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8.

A constructor is called automatically whenever a variable of the class is _______________ .

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declared
accessed
evaluated
destroyed

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9.

Which of these is a syntactically correct prototype for the constructor of a class called `quadratic`?

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quadratic(a, b, c);
quadratic(double a, double b, double c);
double quadratic(double a, double b, double c);
quadratic_constructor(double a, double b, double c);
void quadratic_constructor(double a, double b, double c);

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10.

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11.

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12.

A constructor with no formal parameters is called a _________ constructor.

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default
deficient
simple
working

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13.

True, or false? When defining a new class, you may declare as many constructors as you like.

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true
false

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14.

The value semantics of a class determines how values are copied from one object of the class to another. In C++, the value semantics consists of these two operations:

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assignment operator
copy constructor
default constructor
stream output operator (<<)

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15.

Which of the following is a correct prototype for a COPY CONSTRUCTOR belonging to the throttle class?

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throttle(const throttle &t);
throttle(int size);
void throttle(throttle t);
void throttle(int size);

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16.

Which of the following parts of defining a new class in C++ belong in the HEADER file (e.g., throttle.h)?

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an extended comment which tells folks how to USE the class
the class definition, including prototypes for member functions and declarations for member variables
a macro guard to prevent duplicate definition
complete implementations for all member functions

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17.

True, or false? You should always put a ’using’ statement in the header file for a new C++ class, to help out other programs that will include that header file in their code.

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false
true

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18.

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19.

The function int_to_string takes an integer ’nums’ and returns the equivalent string of digits. For example, the function call int_to_string(33250) returns the equivalent string, "33250".

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Hint: Use a stringstream to help with this conversion. Assume that the enclosing program has included the sstream header file.

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#include <sstream>

#include <iostream>
#include <fstream>
#include <string>
#include <sstream>
#include <cassert>  // provides "assert"

using namespace std;
#define SEPARATOR "#<ab@17943918#@>#"

^^^^

====
#define DOCTEST_CONFIG_IMPLEMENT_WITH_MAIN
#include "doctest.h"

TEST_CASE( "test1" ) {
    std::stringstream cout;
    string val = int_to_string(7785);
    assert(val.length() == 4);
    cout << val;

;
    std::string answer = "7785";
    CHECK( cout.str() == answer );
}

TEST_CASE( "test2" ) {
    std::stringstream cout;
    string val = int_to_string(-3);
    assert(val.length() == 2);
    cout << val;

;
    std::string answer = "-3";
    CHECK( cout.str() == answer );
}

TEST_CASE( "test3" ) {
    std::stringstream cout;
    string val = int_to_string(123454321);
    assert(val.length() == 9);
    cout << val;

;
    std::string answer = "123454321\n";
    CHECK( cout.str() == answer );
}

TEST_CASE( "test4" ) {
    std::stringstream cout;
    string val = int_to_string(-999999);
    if (val.length() != 7) {
    cout << "wrong"; }
    else {
    cout << val; }

;
    std::string answer = "-999999";
    CHECK( cout.str() == answer );
}

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20.

Write a function is_numerical that takes a string called 'input_string' and returns true if that string can be interpreted as a number; otherwise, is_numerical returns false.

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Here is the meaning of the phrase, "string can be interpreted as a number", in the current context:

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- the string is not empty

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- the string has no characters other than '-', '.', '0', '1', '2', '3', '4', '5', '6', '7', '8', '9'

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- the optional '-' character can ONLY be at index 0 (for indicating a negative number)

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- the optional '.' character (for making a decimal point) should NOT appear more than once and should NOT appear to the left of '-'

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- the string must contain AT LEAST ONE DIGIT

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Note: This is a review question. You might find it helpful to write helper functions, call on string class methods, use a for loop, a stringstream, a switch statement, etc. Everything we’ve used so far is fair game. Make a CLEAR PLAN before you start coding.

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#include <sstream>

#include <iostream>
#include <fstream>
#include <string>
#include <sstream>

using namespace std;
#define SEPARATOR "#<ab@17943918#@>#"

^^^^

====
#define DOCTEST_CONFIG_IMPLEMENT_WITH_MAIN
#include "doctest.h"

TEST_CASE( "test1" ) {
    std::stringstream cout;
    cout << is_numerical("3.14159");

;
    std::string answer = "1";
    CHECK( cout.str() == answer );
}

TEST_CASE( "test2" ) {
    std::stringstream cout;
    cout << is_numerical("this_is_a_non_numerical_string");