Robust Input

//Demonstrates the function read_and_clean.

#include <iostream>

#include <cstdlib>

#include <cctype>

void read_and_clean(int& n);

//Reads a line of input. Discards all symbols except the digits.

//Converts the cstring to an integer and sets n equal to the

//value of this integer.

void new_line( );

//Discards all the input remaining on the current input line.

//Also discards the '\n' at the end of the line.

int main( )

{

using namespace std;

int n;

char ans;

do

{

cout << "Enter an integer and press return: ";

read_and_clean(n);

cout << "That string converts to the integer " << n << endl;

cout << "Again? (yes/no): ";

cin >> ans;

new_line( );

} while ( (ans != 'n') && (ans != 'N') );

return 0;

}

void read_and_clean(int& n)

{

using namespace std;

const int ARRAY_SIZE = 6;

char digit_string[ARRAY_SIZE];

char next;

cin.get(next);

int index = 0;

while (next != '\n')

{

if ( (isdigit(next)) && (index < ARRAY_SIZE - 1) )

{

digit_string[index] = next;

index++;

}

cin.get(next);

}

digit_string[index] = '\0';

n = atoi(digit_string);

}

void new_line( )

{

using namespace std;

char symbol;

do

{

cin.get(symbol);

} while (symbol != '\n');

}

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