C++ Programming Help

egeekial · 10-10-2004, 05:34 PM

Ok, I need some help with my C++ homework. I'm not asking anyone here to do it for me... that would defeat the purpose of taking the class. I just need a little bit of help understanding and doing some things. If someone could AIM or ICQ me, that would be great It's all very basic stuff, but I'm just a newbie to programming.

AIM: morgan196
ICQ: 43581290

egeekial · 10-10-2004, 06:22 PM

It's a bit lengthy... but here it goes.

Here is the problem:
Using the getDouble function as an example write your own function readMoney, which reads amount of dollars and cents from the user. The user input should be in the form:
$123.34
That is, it should start with the dollar sign, and then it should have the amount of dollars, then the decimal point, and then 2-digit amount of cents. It should end with any space symbol or a dot. Your function should return 2 integer values (one for dollars and another for cents).

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Here is getDouble:
#include <iostream.h>
#include <ctype.h>
#include <stdlib.h>

// function: getDouble
// goal: The function reads character by character from the
// standard input (cin) and converts them into a floating
// point number. It stops when it reads any character
// but +, -, decimal point or a digit.
// As the result it returns the number read.
double getDouble(void)
{
char ch;
int sign = 1;
double res = 0;
double factor = 10;

cin.get(ch); // read the very first symbol from the user
// check if the first symbol is a sign
if( ch=='-' || ch=='+' ){
if( ch == '-' ) sign = -1;
cin.get(ch); // read the next symbol
}

// repeat the loop while it's a correct symbol
while( isdigit(ch) || (ch=='.' && factor>0.1) ){
if( isdigit(ch) ){
if( factor > 0.1 ){
// we haven't read the decimal point yet
res = factor * res + (ch - '0');
}
else{
// we have read the decimal point by this time
res += (ch - '0') * factor;
factor /= 10;
}
}
else{ // we just read the decimal point
factor = 0.1;
}
cin.get(ch); // read the next symbol
}

return res*sign;
}

int main(void)
{
double num;

cout<<"Enter a floating point number ";
num = getDouble(); // using the new function to read the user's input
cout<<"You entered: "<<num<<endl;

return 0;
}

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My question is how do I output dollars and cents from the function as separate variables.

god_of_cpu · 10-10-2004, 06:34 PM

I won't tell you exactly how to do it, but I'll give you your first clue, first convert you double for dollars into cents represented as an integer. It should then be an easier problem to solve. YOu just have to figure out how many cents are in a dollar then and how many remaining cents you have after you subtract out the whole dollars.

Hint: The modulus operator (%) is your friend.

xBrady · 10-10-2004, 06:45 PM

Are you asking how your function can return two seperate values? As in this case, two integers?

egeekial · 10-10-2004, 06:57 PM

This is what I'm going to do:
void readMoney(int &dollars, int &cents)

Now I just have the problem of trying to input as one variable and break it down into 2... man, I hate doing this >:/

egeekial · 10-10-2004, 07:00 PM

I can't get the cents to work right...

My code so far:

#include <iostream>
#include <stdlib.h>

using namespace std;

void readMoney(int &dollars, int &cents)
{
char money;
double factor = 10;

cout<<"Enter amount of money$: ";

cin.get(money); // read the very first symbol from the user
// check if the first symbol is a dollar sign

if( money == '$' ) cin.get(money); // read the next symbol
else cerr<<"You did not enter a dollar sign ($).";

// repeat the loop while it's a correct symbol
while( isdigit(money) || (money=='.' && factor>0.1) ){
if( isdigit(money) ){
if( factor > 0.1 ){
// we haven't read the decimal point yet
dollars = factor * dollars + (money - '0');
}
else{
// we have read the decimal point by this time
cents = (money - '0') * factor;
cout<<cents;
factor /= 10;
}
}
else{ // we just read the decimal point
factor = 0.1;
}
cin.get(money); // read the next symbol
}

cout<<"Amount in the function: "<<dollars<<"."<<cents<<endl;
}

int main(void)
{
int dollars=0, cents=0;

readMoney(dollars, cents);
cout<<"Amount in the main: "<<dollars<<"."<<cents<<endl;

system("PAUSE");
return 0;
}

[iG] · 10-10-2004, 07:17 PM

'0' is a character. I dont think you want to perform arithmetic with ints and chars

bbrother · 10-10-2004, 08:00 PM

I think you are making this harder than it looks once you check to see if the first character is a dollar sign then you should be able to call your getdouble function and it can do the rest of the work of getting the number input and converting.
Hope this helps