Program always outputs the same, weird number

[doctorkwack101]

This is my very first attempt at C++, and I must be missing something big. This is an assignment for my CS class - you have to write a simple store checkout program. I thought everything looked fine and dandy, but every time I run the program, my checkout total is 5.45e159, no matter what weights I input. Where did I screw up?
-----------------------

#include <cstdlib>
#include <iostream>
#include <string>

using namespace std;

/*
*
*/
double checkout(double produce[]);

int main(int argc, char** argv) {

double input;
double produce[5];
double grandproduce[5];
double total = 0, grandtotal, grosstotal, discount, granddiscount;
int again = 1;

cout << "***** Welcome to Super Fruit/Vegetable Purchaser II Turbo! *****" ;

while (again == 1) {
cout << "\n\nPlease enter the weight (in pounds) for each of the" <<
"\nfollowing purchases.\n";

cout << "Bananas: ";
cin >> produce[1];
grandproduce[1] += input;

cout << "Apples: ";
cin >> produce[2];
grandproduce[2] += input;

cout << "Cucumbers: ";
cin >> produce[3];
grandproduce[3] += input;

cout << "Carrots: ";
cin >> produce[4];
grandproduce[4] += input;

cout << "Oranges: ";
cin >> produce[5];
grandproduce[5] += input;

total = checkout(produce);

grosstotal += total;

if (total > 50.0) {
discount = total * 0.05;
granddiscount += discount;
total -= discount;
}
grandtotal += total;

cout << "Your total comes to $" << total << "." ;
cout << "\nWould you like to do another checkout? Enter 1 for yes or" <<
"\nany other number for no: ";
cin >> again;

}
cout << "*** Total weights ***\n";
cout << "Bananas: " << grandproduce[1] << "\n";
cout << "Apples: " << grandproduce[2] << "\n";
cout << "Cucumbers: " << grandproduce[3] << "\n";
cout << "Carrots: " << grandproduce[4] << "\n";
cout << "Oranges: " << grandproduce[5] << "\n";
cout << "Gross purchases: " << grosstotal << "\n";
cout << "Total discounts: " << granddiscount << "\n";
cout << "Total purchases (discounted): " << grandtotal << "\n";
return 0;

}

double checkout(double produce[]) {

double total;

total += produce[1] * 0.44;
total += produce[2] * 0.99;
total += produce[3] * 1.19;
total += produce[4] * 0.89;
total += produce[5] * 0.79;

return total;
}

[Moschops]

In the function checkout, your total starts at some random value. Set it to zero on creation.

grandproduce[1] += input;
What is this supposed to do? input is some random value you never set.

grosstotal begins with some random value.

There is a theme here. You are creating many variables with random values, and then you start using them without ever setting the value.

[TheIdeasMan]

This doesn't do what you think it does.

cout << "Bananas: ";
cin >> produce[1];
grandproduce[1] += input;

input is uninitialised (always initialise variables to something even zero) and is the cause of the problems with the output.

You probably wanted to do this:

cout << "Bananas: ";
cin >> produce[1];
grandproduce[1] +=  produce[1];

As this will put the input into your array.

[doctorkwack101]

Thank you very much - I realized my stupid mistakes and fixed them. I will be sure to initialize variables from now on. Java spoiled me. :P

[Moschops]

(always initialise variables to something even zero)

As an aside, C and C++ very explicitly and deliberately by design allows the creation of uninitialised variables. There are good cases when initialising them (for example, to zero) is not wanted.

[TheIdeasMan]

@doctorkwack101

I forgot to mention, please use code tags in future - the <> button on the right.

@Moschops

OK, I see what you are saying. Just wondering whether to initialise to something is better than not initialising at all.

I was thinking that uninitialised variables is one of the leading reasons for mistakes in code, and especially for a newbie, it is a good idea to initialise.

It is of course different in C++, where initialisation should be done in constructors, but I see a lot of newbie's writing C code with some couts & cin.