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Setting up an Invalid Response

ET21 (35)
Basically the whole purpose of this program is to prompt the user to use a calculator. Choices 1-6 are valid, but I want to set it up where selecting any other number outside of 1-6 to be Invalid, and will display an 'Invalid Choice' message, and then go back to the main menu. Been trying to get this for the past 2 hours, and it's a headache (I'm a noob to programming). The main program does work properly, it's the 'Invalid' setup that is giving me problems

Any suggestions or help is greatly appreciated!

Code:

#include <iostream>
#include <iomanip>

using namespace std;

int main()

{

int loop=1;
int choice;

while (loop!=6)
{
system("CLS");
cout << "::Program 3: Geometry Calculator (The Expanded Edition)::\n\n" //Main Menu
<< "1. Area of a Circle\n"
<< "2. Area of a Triangle\n"
<< "3. Area of a Parallelogram\n"
<< "4. Area of a Trapezoid\n"
<< "5. Area of an Ellipse\n"
<< "6. Exit\n\n";

cin >> choice;

switch(choice)
{
case 1: //Area of circle coding.
system("CLS");

float pi, radius, area;
cout << "::Area of a Circle::\n\n"
<< "Enter your radius: ";
cin >> radius;

pi = 3.14159;

area = pi * (radius*radius);

cout << "The area of the circle is " << area << "." << endl;
system("PAUSE");
}
switch(choice)
{
case 2: //Area of triangle coding.
if(choice==2)
system("CLS");

float base, height, a2;
cout << "::Area of a Triangle::\n\n"
<< "Enter your base: ";
cin >> base;

cout << "Enter your height: ";
cin >> height;

a2 = base * height / 2;

cout << "Your result is " << a2 << "." << endl;
system("PAUSE");
}
switch(choice)
{
case 3: //Area of parallelogram coding.
if(choice==3)
system("CLS");

float b2, h2, a3;
cout << "::Area of a Parallelogram::\n\n"
<< "Enter your base: ";
cin >> b2;

cout << "Enter your height: ";
cin >> h2;

a3 = b2 * h2;

cout << "Your result is " << a3 << "." << endl;
system("PAUSE");
}
switch(choice)
{
case 4: //Area of trapezoid coding.
if(choice==4)
system("CLS");

float b3, b4, h3, a4;
cout << "::Area of a Trapezoid::\n\n"
<< "Enter your first base: ";
cin >> b3;

cout << "Enter your second base: ";
cin >> b4;

cout << "Enter your height: ";
cin >> h3;

a4 = (b3 + b4) / 2 * h3;

cout << "Your result is " << a4 << "." << endl;
system("PAUSE");
}
switch(choice)
{
case 5: //Area of Ellipse coding.
if(choice==5)
system("CLS");

float smaa, smia, a5, pi2;
cout << "::Area of an Ellipse::\n\n"
<< "Enter your Semi-Major Axis: ";
cin >> smaa;

cout << "Enter your Semi-Minor Axis: ";
cin >> smia;

pi2 = 3.14159;

a5 = pi2 * smaa * smia;

cout << "Your result is " << a5 << "." << endl;
system("PAUSE");
}
switch(choice)
{
case 6: //Exit coding.
if(choice==6)
system("CLS");

cout << "Good-bye!\n\n";
system("PAUSE");
exit(0);
}
switch(choice)
{
if(choice!=6)
system("CLS");

cout << "Your choice is invalid";
system("PAUSE");
}

}
}

Last edited on
LB (13399)
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int choice = 0;
std::cout << 'P';
do
{
    std::cout << "lease enter a whole number in the range [1, 5]: " << std::flush;
    std::cin >> choice;
    if(!std::cin || choice < 1 || choice > 5)
    {
        std::cin.clear();
        choice = 0;
        std::cout << "Invalid response, p";
    }
    else
    {
        break;
    }
}while(true);
std::cout << "The number you entered, " << choice << ", was acceptable." << std::endl;
Please enter a whole number in the range [1, 5]: 7
Invalid response, please enter a whole number in the range [1, 5]: 2
The number you entered, 2, was acceptable.
Last edited on
Smac89 (1727)
No need to use multiple switch statements

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#include <iostream>
#include <iomanip>

using namespace std;

void message()
{
  system("CLS");
  cout << "::Program 3: Geometry Calculator (The Expanded Edition)::\n\n" //Main Menu
  << "1. Area of a Circle\n"
  << "2. Area of a Triangle\n"
  << "3. Area of a Parallelogram\n"
  << "4. Area of a Trapezoid\n"
  << "5. Area of an Ellipse\n"
  << "6. Exit\n\n";
}

int main()
{
  int choice = 0;
  message();
  
  while (1)
  {    
    cout << "\nEnter one of the options please\n";
    cin >> choice;
    
    switch(choice) 
    {
      case 1: //Area of circle coding. 
	system("CLS");
	
	float pi, radius, area;
	cout << "::Area of a Circle::\n\n"
	<< "Enter your radius: ";
	cin >> radius;
	
	pi = 3.14159; 
	
	area = pi * (radius*radius);
	
	cout << "The area of the circle is " << area << "." << endl;
	system("PAUSE");
	break;
	
      case 2: //Area of triangle coding.
	system("CLS");
	
	float base, height, a2; 
	cout << "::Area of a Triangle::\n\n"
	<< "Enter your base: "; 
	cin >> base; 
	
	cout << "Enter your height: ";
	cin >> height;
	
	a2 = base * height / 2;
	
	cout << "Your result is " << a2 << "." << endl; 
	system("PAUSE");
	break;
	
      case 3: //Area of parallelogram coding. 
	system("CLS");
	
	float b2, h2, a3;
	cout << "::Area of a Parallelogram::\n\n"
	<< "Enter your base: ";
	cin >> b2;
	
	cout << "Enter your height: ";
	cin >> h2;
	
	a3 = b2 * h2;
	
	cout << "Your result is " << a3 << "." << endl;
	system("PAUSE");
	break;
	
      case 4: //Area of trapezoid coding.
	system("CLS");
	
	float b3, b4, h3, a4;
	cout << "::Area of a Trapezoid::\n\n"
	<< "Enter your first base: ";
	cin >> b3;
	
	cout << "Enter your second base: ";
	cin >> b4;
	
	cout << "Enter your height: ";
	cin >> h3; 
	
	a4 = (b3 + b4) / 2 * h3;
	
	cout << "Your result is " << a4 << "." << endl;
	system("PAUSE");
	break;
	
      case 5:	 //Area of Ellipse coding.
	system("CLS");
	
	float smaa, smia, a5, pi2;
	cout << "::Area of an Ellipse::\n\n"
	<< "Enter your Semi-Major Axis: ";
	cin >> smaa;
	
	cout << "Enter your Semi-Minor Axis: ";
	cin >> smia;
	
	pi2 = 3.14159;
	
	a5 = pi2 * smaa * smia;
	
	cout << "Your result is " << a5 << "." << endl;
	system("PAUSE");
	break;
	
      case 6:	 //Exit coding. 
	system("CLS");
	
	cout << "Good-bye!\n\n";
	system("PAUSE");
	return 0;
	break;
	
      default:
	
	cerr << "Your choice is invalid\n\n";
	message();
	system("PAUSE");
	break;
    }
    
  }
}
ET21 (35)
So you can combine all switch statements into one long code. I was always under the impression that each one had to have it's own { } set
LB (13399)
You only need to use {} if you want to declare variables in a case.
ET21 (35)
Ahhh ok. Now if I wanted to have it loop back to the main menu after completing each case, would I need to put a loop statement to do this?
LB (13399)
It looks like Smac's code already does this.
ET21 (35)
It asks for a choice at the end of each choice. What I want to modify is have it loop back to the main menu screen at the end.

Like it would be:
Enter your radius: ....
Your Area is:.....

Press any key to continue....

*Main Menu Screen*
LB (13399)
Move line 21 to line 24 (referencing line numbers in Smac's post)
ET21 (35)
That did it. Thank you Smac and L B for your help. Just a simple operation takes a lot of coding.

Starting to like programming hehe
LB (13399)
ET21 wrote:
Just a simple operation takes a lot of coding.
This isn't "a lot of coding", it's just tedious coding because you haven't learned how to factor & refactor code yet ;)
Last edited on
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