set validation

hello all i am having a problem setting validation. i have written this code and it works. when i try and put in validation with if statements it keeps crashing the program. i have no idea where to go from here. here is what i am trying to do:

Modify my StudentGrade class that the "set" methods perform data validation. A student ID should be in the range of 10000-50000, and a grade should be in the range 0 - 100. Use a single "if" statement (using the && operator) in each "set" method.

#include <iostream>
using std::cout;
using std::cin;
using std::endl;

#include <string>
using std::string;
using std::getline;

Code:

	class StudentGrade
  {
	public:
	//function that sets the student ID
	void setStudentID( string number )
	{
		studentID = number; //store the course name in the object
	}

	//function that gets the student ID
	string getStudentID()
	{
		return studentID; //returns the objects Student ID
	}

	void setTestScore( string score )
	{
		testScore = score;
	}

	string getTestScore()
	{
		return testScore;
	}

	void displayMessage()
	{
		cout << "Student " << getStudentID() << " has a score of " 			<< getTestScore() << endl;
	}
	private:
	string studentID;
	string testScore;
};

	int main()
   {
	string studentIDnumber;
	string studentTestscore;
	StudentGrade myStudentID;
	
	if ( studentIDnumber < 10000 && >50000 )
	cout<< "The number must be between 10000 - 50000. ";

	else
	cout << "Student ID is: " <<myStudentID.getStudentID() << endl;

	cout << "\nPlease enter the Student ID number:" << endl;
	getline( cin, studentIDnumber );
	myStudentID.setStudentID( studentIDnumber );

	cout << endl;

	cout << "Student test score is: " <<myStudentID.getTestScore() << 	endl;

	cout << "\nPlease enter the Student Test Score:" << endl;
	getline( cin, studentTestscore );
	myStudentID.setTestScore( studentTestscore );

	cout << endl;

	myStudentID.displayMessage();
	return 0;
   }

I would expect something like a student id and test scores would be integer values and not strings.

Code:

string studentIDnumber;
string studentTestscore;
StudentGrade myStudentID;
	
if ( studentIDnumber < 10000 && >50000 )
    cout<< "The number must be between 10000 - 50000. ";

You can't test a string and an int type like this. Also, the general syntax of the test is incorrect. Testing like you are doing should be using logical or (||) instead of logical and (&&). It should be something like:

Code:

int studentIDnumber;
...
if( studentIDnumber < 10000 || studentIDnumber > 50000 )
    cout<< "The number must be between 10000 - 50000. ";

Make your data types ints instead of strings. Also, you need to initialize your values before you start testing them.

the problem is i have to use and if statement with the && operator. that is what is confusing me.

Code:

if( studentIDnumber >= 10000 && studentIDnumber <= 50000 )
{
    // Good data, do something
}
else
{
    // Bad data
    cout<< "The number must be between 10000 - 50000. ";
}

thanks, i must be a moron, i cant figure out how to rewrite the code to make it work. thanks for the help