Functions to help beginners.

[N7960pDG]

Here is some code to help beginners with functions. Post your questions on what you don't understand. Enjoy!

 #include <iostream>
#include <string>
#include <cmath>
#include <cstdlib>
#include <windows.h>
#include <limits>
#include <limits.h>
#include <climits>


using namespace std;
bool die(const string & msg);
void restore();

//Function prototypes 
double triple(double x); //1
double times9(double x); //2
void triple(double & result, double x); //3
void times3(double & x); //4
void countdown(unsigned seconds ); //5
double getDouble( const string & prompt); //6
double getDoubleRetry( const string & prompt ); //7
string getString( const string & prompt ); //8
void output(unsigned howMany, const string & msg ); //9
string remove( char c, const string & s ); //10
string remove(const string & junk, const string & s); //11
bool prime( unsigned n ); //12
unsigned primes(unsigned max ); //13
double average(); //14
double averagePositive(); //15


int main(){

	cout<<"Function1: " <<triple(1.1) <<endl; //1

	cout<<"Function2: " <<times9(3) <<endl; //2

	double result;
	triple(result ,3); cout<<"Function3: " <<result <<endl; //3

	double x=3;
	times3(x); cout<<"Function4: " <<(x) <<endl; //4
	
	cout<<"Function5: Countdown with Timer = " <<endl; countdown(5); 
	cout<<endl; //5

	cout<<"Function6: " << getDouble("Input") <<endl; //6

	cout <<"Function7: " << getDoubleRetry("Input again") 
		<< endl << endl; //7

	cout<<"Function8: " <<getString("Input String") <<endl;
		string getString( const string & prompt ); //8
	
	cout<<"Function9: " <<endl; output(4, "Hello Professor"); 
	cout<<endl; //9
		
	cout<<"Function10: " <<remove('p', "Pinapple") <<endl; //10
	
	cout<<"Function11: " <<remove( "aeiou", "Pineapple" ) <<endl;
	//11
		
	cout<<"Function12: 1 = prime, 0 = not prime." << endl; 
	cout << "33: " << prime(33) << endl;
	cout << "3: " << prime(3) << endl << endl; 
	//12

	cout<<"Function13: " <<primes(100) <<endl; //13

	cout<<"Function14: " <<average() <<endl; //14

	cout<<"Function15: " <<averagePositive() 
		<<endl;//15

} //End Main

//Begin
//die function............................................
bool die(const string & msg){
	cout<< "Fatal Error: " <<msg <<endl;
	exit(EXIT_FAILURE);
}

//restore function
void restore(){
	cin.clear(); 
   cin.ignore(10000, '\n');
}




//FUNCTIONS
double triple(double x){
	 return (3 * x);
}//1.................................................

double times9(double x){
	return (triple(triple(x)));
}//2.................................................

void triple(double & result, double x){
	result = (triple(x));
}//3.................................................

void times3(double & x){
	x = (triple(x));
} //4................................................

void countdown( unsigned seconds ){
	for( ; seconds>0; seconds--){
		Sleep(1000);
		cout<<seconds <<endl <<endl;
	}if (seconds == 0){
		cout<<"BLAST OFF! " <<endl;}
} //5...............................................

double getDouble( const string & prompt ){
	cout<<"Please input a double ";
	double inputPrompt;
	cin>> inputPrompt
		|| die("Invalid, please enter a double number");
	return (inputPrompt);
} //6.................................................

double getDoubleRetry(const string & prompt){
	double inputPrompt1;
	cout<<"Please input a double again ";
	for (;;){ if (!(cin>> inputPrompt1)){
			restore();
			cout<<"Please input a valid number: ";
		}
		else{
			return inputPrompt1;
		}//else
	} // for loop
} //7....................................................

string getString( const string & prompt ){
	string inputString;
	cout<< prompt <<endl;
	cin>> inputString || 
		die("Please enter string again: Input failure");
	return inputString;
} //8...................................................

void output( unsigned howMany, const string & msg ){
	for (;howMany > 0;howMany--){
		cout <<msg <<endl;
	}
} //9...................................................

string remove(char c, const string & s){
	string removedLtr;
	for (unsigned character = 0; character < s.size(); character++){
		if (!(s[character] == c)){
			removedLtr += s[character];
		}
	}return removedLtr;
} //10......................................................

string remove( const string & junk, const string & s ){
	string removeLtrs1 = s;
	for (unsigned character = 0; character < junk.size(); character++){
		removeLtrs1 = remove(junk[character], removeLtrs1);
	}
	return (removeLtrs1);
}//11........................................................

bool prime(unsigned n){
	if (n < 4 && n > 1){
		return true;
	}if (!(n % 2 == 0)){
		for (unsigned f = 3;; f++){
			if (f > (n / f)){
				return true;
			}if (n % f == 0){
				return false;
			}//end inside if
		}//end for
	}//outside if end
	else{
		return false;
	}//else end
} //12......................................................

unsigned primes(unsigned max){
	unsigned pCounter = 0;
	for (unsigned begin = 2; begin <= max; begin++){
		if (prime(begin)){
			pCounter++;
		}
	}return (pCounter);
} //13......................................................

double average(){
	cout<<"Function14: input numbers for average " <<endl
		<<"non-number to quit " <<endl;
	double i; 
	double total = 0;
	double count = 0;
	double avg = 0;
	for (;;){
		if (!(cin >> i)){
			restore();
			if (count == 0){die("No Number Inputs");
			}//end inside if
			else {break;
			}//end else
		}//end outside if
		count++;
		total += i;
	} // End for
	avg = total / count;
	return avg;
}//14......................................................

double averagePositive(){
	cout<<"Function15: input numbers for positive # average "
		<<endl <<"non-number to quit " <<endl;
	double i; 
	double total = 0; 
	double count = 0;
	double avg = 0;
	for (;;){
		if (!(cin >> i)){
			restore();
			if (count == 0){die("No Number Inputs");
			}//inside if
			else {break;
			}//end else
		}//end outside if
		if (i > 0){
			count++;
			total += i;
		}//end if
	} // End for
	avg = total / count;
	return avg;
}//15........................................................... 

[keskiverto]

I don't understand, why an another (now deleted) account posted very recently very similar threads.

I don't understand how posting such code helps anyone. All those operations are simple and such that a "beginner" would learn and benefit much more if they have to think and practise rather than blindly copy-paste (IMHO bad style) code.

[N7960pDG]

Good Point, just thought I would help. Some people learn from not only doing, but also seeing and tracing the code to see what does what. This gives them the seeing part to maybe help when they are stuck, trying to code their own ideas to practice, IMHO. Also, I noticed someone doing it the other day, so I figure I would give what I have to add vice it being held up on my computer doing nothing for me anymore.