trouble with a project

[justindjohnson77]

Write your question here.
I want for any user to put in only 9 digits and if its less than nine digits or more than nine digits, i want for my program to redirect them to input only nine digits before going through the rest of the program. I know it requires a loop but in my class we haven't covered more advanced issues

Put the code you need help with here.

cout << "PLEASE ENTER THE PATIENT 9 DIGIT MEDICAL RECORD NUMBER:" << endl;
cin >> mrn;
if (mrn <= 111111111)
{
cout << "Please enter a nine digit medical record number." << endl;
}
if (mrn >= 999999999)
{
cout << "Please enter a nine digital medical record number." << endl;
}

[nick2361]

I'm also a learner :), but to my mind, you will need a recursive function for that

[nick2361]

#include <iostream>

using namespace std;

void medical(int mrn) {
	if (mrn >= 100000000 && mrn <= 999999999) {
		cout << "entering 9-digit medical number was successful!\n";
	}
	else {
		cout << "PLEASE ENTER THE PATIENT 9 DIGIT MEDICAL RECORD NUMBER, YOUR ENTERED NUMBER ISN'T 9-DIGIT ONE:\n";
		cin >> mrn;
		medical(mrn);
	}
}

int main() {

	int mrn;
	cout << "PLEASE ENTER THE PATIENT 9 DIGIT MEDICAL RECORD NUMBER:\n";
	cin >> mrn;
	medical(mrn);

	system("pause");
	return 0;
}

the code above takes a number from user and using function medical, determines whether it's 9-digit one or not. if it is, prints success, if not, prompts the user to input another number and the function calls itself for the new number

[Chervil]

Recursion and looping often amount to the same thing. Here, just a while loop.

Note: I wasn't sure about the limits, this code allows 100000000 and 999999999 which are both valid 9-digit numbers.

#include <iostream>

using namespace std;

int main()
{
    unsigned int mrn;
    
    cout << "PLEASE ENTER THE PATIENT 9 DIGIT MEDICAL RECORD NUMBER:" << endl;
    
    while (!(cin >> mrn) || (mrn < 100000000) || (mrn > 999999999))
    {
        cout << "Invalid input\nPlease enter a nine digit medical record number.\n";
        cin.clear();               //. reset status flags
        cin.ignore(1000, '\n');    // discard input until end of line
    }

    cout << "Thank you\nMedical Record Number: " << mrn << '\n';

}

[Chervil]

@nick2361 I think you will need to pass the parameter by reference, or the value entered is simply thrown away.

[Chervil]

Another possibility is to enter the user input as a string, check that the length is 9 characters, and that all of them are numeric. That would allow numbers such as "000000000". You might further add a check that the very first character of the string was not '0'.

[nick2361]

@chervil, if we want to use the applied number in main(), yes we will have to pass by reference, just adding "&" will do: void medical(int &mrn).