C++ A class BCheckString that is derived from the C++ Standard Library string cl
ID: 3919587 • Letter: C
Question
C++
A class BCheckString that is derived from the C++ Standard Library string class performs bounds checking and throws an exception. The BCheckString class will have two member functions:
1) A BCheckString(string s) constructor that receives a string object passed by value and passes it on to the base class constructor. It just calls the base class constructor using its constructor initialization list.
2) A overloaded operator function, char operator[ ](int k), throws an exception, a BoundsException object (i.e., StrExcept()) if its parameter, k is out bounds (i.e., negative or greater than or equal to the length of the string), otherwise it will return the character at position k in the string with calling operator [] in the string base class.
main function that attempts to access characters that are within and outside the bounds of a suitably initialized BCheckString objects
Explanation / Answer
#include <iostream>
#include <string>
#include <stdexcept>
using namespace std;
class StrExcept {
protected:
string str;
int len;
public:
StrExcept(int x,int len)
{
if (x<0)
{
throw 1;
}
else if (x>=len)
{
throw 2;
}
}
}; //String Out of Bounds Exception
// COMPLETE
class BCheckString
{
string str1;
int len1;
public:
BCheckString(string s)
{
str1=s;
len1=str1.length();
}
int length()
{
return str1.length();
}
char& operator[] (int x)
{
StrExcept s(x,len1);
return str1[x];
}
};
int main()
{
//Explain program to user
cout << "This program demonstrates bounds checking on string object.";
//Get string from user and create boundCheck string object
cout << " Enter a string: ";
string str;
getline(cin, str);
BCheckString h(str);
//Let user access characters at specified positions in the string
//COMPLETE
cout << "Legitimate string positions are: " << 0 << ".." << h.length() -1 << endl;
for (int k = 1; k <= 5; k++)
{
cout << "Enter an integer describing a position inside or outside the string: ";
int pos;
cin >> pos;
try {
cout << "The character at position " << pos << " is " << h[pos] << endl;
}
catch (int excp)
{
if(excp==1)
{
cout <<"err : [position below range, ie pos<0]"<< endl;
}
else
{
cout <<"err : [position beyond range, ie pos> length of char]"<< endl;
}
}
}
return 0;
}
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