C++ without fear exercise 5.1.2 help!

[Irishfitz]

There is an exercise in this book that asks to make an array of 5 integers, then print all of them and then the sum of all the numbers. I thought i knew how to do this but I don't think I fully understand arrays yet to do this. any help is appreciated.

Here's my code so far

#include <iostream>

using namespace std;

int main()
{
    int jack[5] = {100,300,900,400,500};
    int x = 0;

    while(x < 5){
        cout << jack[x] + jack[x++] << endl;

    }

}

[jidder]

Your gonna want to make a temp variable such as total and then add each consecutive array index to it like

int total(0);
total = total + jack[i];

it might also be easier to use a for loop if you have covered those yet.

[vlad from moscow]

This program

#include <iostream>

using namespace std;

int main()
{
    int jack[5] = {100,300,900,400,500};
    int x = 0;

    while(x < 5){
        cout << jack[x] + jack[x++] << endl;

    }
}

has undfined behavior. You may not use postfix increment operator of a variable with the variable itself in the same expression because the order of evaluation of subexpressions is undefined.

Your tasks are being done simply the following way

#include <iostream>

using namespace std;

int main()
{
    int jack[5] = {100,300,900,400,500};

    for ( int x : jack ) std:;cout << x << ' ';
    std::cout << std::endl;

    int sum = 0;
    for ( int x : jack ) sum += x;

    std::cout << "The sum is equal to " << sum << std::endl;
 }

If your compiler does not support the range-based for statement then try to rewrite the loops yourself using the ordinary for statement.

[Irishfitz]

Jidder: im going to have to make a function called total? also i would use a for loop. but im using while to make it as basic as possible.

Vlad: im sorry, im a noob, i basically have no flippin idea what you just said. i apologize

[vlad from moscow]

I not only said but also showed you valid code.:) So investigate it.

[Irishfitz]

ya also you dont have to use std:: because that's what using namespace std; does. also the way you put the for loops was a little confusing. but i think i got the jist of your program. thank you vlad

[vlad from moscow]

I simply did not take into account your statement

using namespace std;

because I copied and pasted your original code as is.

But in any way it is not an error even if this statement is included. I advice simply to remove it.:)

[Irishfitz]

yeah my compiler doesnt support range-based. and i have no idea what that even is so how would I re-write that?

[vlad from moscow]

As I said use the ordinary for statement instead of the range-based for statement. You should understand what the for statemnet in my code does and substitute it for your for statement.

[Irishfitz]

but i dont. all i know is you declared the variable x as an integer and assigned it no value then use ':' and then the name of my array... is it basically the same thing as jack[x]?

[Irishfitz]

whatever man im way more confused than I was earlier. thanks for the help.

[vlad from moscow]

For example the following rahge-base for statement

    for ( int x : jack ) std:;cout << x << ' ';
    std::cout << std::endl;

can be rewritten as

    for ( int i = 0; i < 5; i++ ) std:;cout << jack[i] << ' ';
    std::cout << std::endl;

[Irishfitz]

okay so I got it. thanks vlad sorry for being difficult.

#include <iostream>

using namespace std;

int main()
{
    int jack[5] = {100,300,900,400,500};
    int sum = 0;

    for (int x = 0; x < 5; x++){
        cout << jack[x] << endl;
        sum += jack[x];
    }

cout << sum << endl;


 }

[vlad from moscow]

Only it is a bad style of programming to use such identifiers as x as indexes of arrays in such simple loops. It is better to use identifiers i, j, k, l, m, n. This tradition came from FORTRAN.