How to implement char input validation in C++

Question

I need to create a program that calculates the price of a table being built.

The main() function should call the following functions:

1. A function which accepts from standard in the number of chairs to go with the table.

2. A function which accepts from standard in the surface area (in m2) of the table.

3. A function which accepts from standard in the type of wood used to build the table and chairs; 'm' for mahogony, 'o' for oak or 'p' for pine. Ideally any other entry should be rejected.

4. A function that takes the number of chairs (N), the surface area of the table (S) and the type of wood (x) to calculate the price. The price for a table is x(S + 1/2N) where x is $50, $100 and $150 respectively for pine, oak, and mahogony.

5. A function to display the details of the purchase.

Results at the moment:

At the moment my code will only calculate the price of the table with 'm'(mahogony) and not the other two materials. For example:

Number of chairs: 5
Surface area of table (m2): 5
Wood type: m
Total = 1125

If I change the wood type to 'o' or 'p', the same price will result.

Code:

#include <iostream>

using namespace std;

int main(){
int N;
cout << "Number of chairs: ";
cin >> N;

int S;
cout << "Surface area (in meters squared) of the table: ";
cin >> S;

cout << "Type of wood ('m' = mahogony, 'o' = oak, 'p' = pine): ";
char x;
cin >> x;

while(x != 'm' && x != 'o' && x != 'p'){
    cout << "Error. Invalid input. Please try again" << endl;
    cout << "Type of wood ('m' = mahogony, 'o' = oak, 'p' = pine): ";
    cin >> x;
}

int total;
if(x = 'm'){
    total = 150*(S + (0.5*N));
} else if(x = 'o'){
    total = 100*(S + (0.5*N));
} else if(x = 'p'){
    total = 50*(S + (0.5*N));
}

cout << "--------------------\n";
cout << "Details of purchase:\n";
cout << "--------------------\n";
cout << "Number of chairs: " << N << endl;
cout << "Surface area of table (m2): " << S << endl;
cout << "Wood type: " << x << endl;
cout << "Total = " << total << endl;

return 0;
}

Answer 1

#include <iostream>

using namespace std;

int main(){
int N;
cout << "Number of chairs: ";
cin >> N;

int S;
cout << "Surface area (in meters squared) of the table: ";
cin >> S;

cout << "Type of wood ('m' = mahogony, 'o' = oak, 'p' = pine): ";
char x;
cin >> x;

while(x != 'm' && x != 'o' && x != 'p'){
    cout << "Error. Invalid input. Please try again" << endl;
    cout << "Type of wood ('m' = mahogony, 'o' = oak, 'p' = pine): ";
    cin >> x;
}

int total;
if(x == 'm'){
    total = 150*(S + (0.5*N));
} else if(x == 'o'){
    total = 100*(S + (0.5*N));
} else if(x == 'p'){
    total = 50*(S + (0.5*N));
}

cout << "--------------------\n";
cout << "Details of purchase:\n";
cout << "--------------------\n";
cout << "Number of chairs: " << N << endl;
cout << "Surface area of table (m2): " << S << endl;
cout << "Wood type: " << x << endl;
cout << "Total = " << total << endl;

return 0;
}

You must == to check a condition and = for assigning value

Answer 2

#include <iostream>
using namespace std;
int main(){
    float N;
    cout << "Number of chairs: ";
    cin >> N;
    float S;
    cout << "Surface area (in meters squared) of the table: ";
    cin >> S;
    cout << "Type of wood ('m' = mahogony, 'o' = oak, 'p' = pine): ";
    char x;
    cin >> x;
    while(x != 'm' && x != 'o' && x != 'p'){
        cout << "Error. Invalid input. Please try again" << endl;
        cout << "Type of wood ('m' = mahogony, 'o' = oak, 'p' = pine): ";
        cin >> x;
    }
    float total=0.f;
    if(x == 'm'){
        total = 150.f*(S + (0.5f*N));
    } else if(x == 'o'){
        total = 100.f*(S + (0.5f*N));
    } else if(x == 'p'){
        total = 50.f*(S + (0.5f*N));
    }
    cout << "--------------------\n";
    cout << "Details of purchase:\n";
    cout << "--------------------\n";
    cout << "Number of chairs: " << N << endl;
    cout << "Surface area of table (m2): " << S << endl;
    cout << "Wood type: " << x << endl;
    cout << "Total = " << total << endl;
    return 0;
}