PS # 13
1)
The following code uses two arrays, one to store products and another to store product IDs (a better organization would be to use a single array of a class or struct, but that is not the subject of this Programming Project). The function getProductID takes as input the two arrays, the length of the arrays, and a target product to search for. It then loops through the product name array; if a match is found, it returns the corresponding product ID:
int getProductID( int ids[], string names[],int numProducts, string target)
{ for ( int i=0; i < numProducts; i++)
{
if (names[i] == target)
return ids[i];
}
return -1; // Not found
}
int main() // Sample code to test the getProductID function
{
int productIds[] = {4, 5, 8, 10, 13}; string products[] = {"computer","flash drive",
"mouse","printer","camera"};
cout << getProductID(productIds, products, 5, "mouse") << endl; cout << getProductID(productIds, products, 5, "camera")
<< endl;
cout << getProductID(productIds, products, 5, "laptop")
<< endl; return 0;
}
One problem with the implementation of the getProductID function is that it returns the special error code of -1 if the target name is not found. The caller might ignore the -1, or later we might actually want to have -1 as a valid product ID number. Rewrite the program so that it throws an appropriate exception when a product is not found instead of returning -1.
2)
A function that returns a special error code is usually better accomplished throwing an exception instead. The following class maintains an account balance.
class Account
{
private: double balance;
public:
Account()
{ balance = 0;
}
Account( double initialDeposit)
{ balance = initialDeposit;
}
double getBalance()
{ return balance;
}
// returns new balance or -1 if error double deposit( double amount)
{ if (amount > 0) balance += amount;
else
return -1; // Code indicating error
return balance;
}
// returns new balance or -1 if invalid amount double withdraw( double amount)
{ if ((amount > balance) || (amount < 0))
return -1;
else balance -= amount;
return balance;
}
};
Rewrite the class so that it throws appropriate exceptions instead of returning -1 as an error code. Write test code that attempts to withdraw and deposit invalid amounts and catches the exceptions that are thrown.
