Question

C++ with comments please!

The following program will read a number from the user and store the number as a string of characteristics. Convert this string to an integer. Before conversion, test for a non Number exception, which occurs if one or more of the characters is not a digit. Your program should throw an exception if it detects a - sign before the number. The following is a sample output (your output should exactly look like it if you have the same input) Please enter a number (ZOF to end) : 4 The number entered was: 4 Please enter a number (EOF to end): 28 The number entered was: 28 Please enter a number (EOF to end): -257 The number entered was: -257 Please enter a number (EOF to end) : a23 INVALID INPUT: non-Integer detected Please enter a number (EOF to ond): 3423 INVALID IMPUT: non-integer detected Please enter a number (EOT to end): -3413-3 INVALID INPUT: non-integer detected Please enter a number (EOF to end): -4-8 INVALID INPUT: non-integer detected Please enter a number (EOF to end): Az

// numberverifier.cpp

#include <iostream>

#include <exception>

using std::cout;

using std::cin;

using std::endl;

#include <cmath>

#include <cstring>

class nonNumber : public exception {

public:

/* write definition for the constructor */ -- Message is “An invalid input was entered”

};

int castInput( char *s )

{

char *temp = s;

int result = 0, negative = 1;

// check for minus sign

if ( temp[ 0 ] == '-' )

negative = -1;

for ( int i = strlen( s ) - 1, j = 0; i >= 0; i--, j++ ) {

if ( negative == -1 && i == 0 )

continue;

if ( isdigit( temp[ i ] ) )

result += ( temp[ i ] - '0' ) * pow( 10, j );   

else

/* write code to throw nonNumber exception */

}

return result * negative;

}

int main()

{

char input[ 100 ];

int convert;

cout << "Please enter a number (EOF to end): ";

while ( cin >> input ) {

/* write try block that calls castInput */

/* write catch statement that catches any exceptions

that the call to castInput might have thrown */

cout << "\n\nPlease enter a number (EOF to end): ";

}

cout << endl;

return 0;

}

Answer 1

#include <iostream>
#include <exception>

using std::cout;
using std::cin;
using std::endl;
using std::exception;
#include <cmath>
#include <cstring>

class nonNumber : public exception {
public:
virtual const char* what() const throw()//exepction handler error containd in what() function
{
return "INVALID INPUT: Non-Integer detected";
}

} ex;//exeption instance created

int castInput( char *s )
{
char *temp = s;
int result = 0, negative = 1;

// check for minus sign
if ( temp[ 0 ] == '-' )
negative = -1;

for ( int i = strlen( s ) - 1, j = 0; i >= 0; i--, j++ ) {
if ( negative == -1 && i == 0 )
continue;
  
if ( isdigit( temp[ i ] ) )
result += ( temp[ i ] - '0' ) * pow( 10, j );   
else
throw nonNumber();
// throwing the error to the non number exception class


}
return result * negative;
}

int main()
{
char input[ 100 ];
int convert;
cout << "Please enter a number (EOF to end): ";

while ( cin >> input ) {

try{
convert=castInput(input);
cout<<"The number entered Was "<<convert;
}
catch(nonNumber& ex){
cout<<ex.what()<<endl;//what() Method contains specific error message it is called with ex instance here
  
}
cout << "\n\nPlease enter a number (EOF to end): ";

}

cout << endl;
return 0;
}

Here is the output:

:   

Please enter a number (EOF to end) : 44 The number entered Was 44 Please enter a number (EOF to end): ff INVALID INPUT: Non-Integer detected Please enter a number (EOF to end): 44f INVALID INPUT: Non-Integer detected Please enter a number (EOF to end): -66 The number entered Was -66 Please enter a number (EOF to end): -66-6 INVALID INPUT: Non-Integer detected Please enter a number (EOF to end): fff555 INVALID INPUT: Non-Integer detected Please enter a number (EOF to end): 123d INVALID INPUT: Non-Integer detected