c++ Arrays

[whOOper]

Hi, I've read over the lessons for arrays and I can't figure out how to use arrays in math problems. The example I was given uses the array in math with a for loop, but I want to uses the arrays in just basic math statements.

Thanks for the answers. whOOper.

[Disch]

Arrays are just groups of variables. For example if you have 3 things you need to keep track of, you could either store them individually as 3 variables:

int var0;
int var1;
int var2;
...
if(var1 == 15)
  var1 = 10;

Or you could group them together as an array:

int var[3];
...
if(var[1] == 15)
  var[1] = 10;

The above two code snippits pretty much do exactly the same thing. The advantage to using arrays is that you can use an "index" to select a specific variable. Like say you get the input from the user:

int which;
cout << "Input which var you would like to see (0-2): "
cin >> which;  // assume user inputs 0,1, or 2 

to print the appropriate variable if they're all defined seperately is a chore, and would require a large if/else chain or a switch statement:

     if(which == 0)   cout << var0;
else if(which == 1) cout << var1;
else if(which == 2) cout << var2;  // blech!

// or

switch(which)
{
case 0:  cout << var0; break;
case 1:  cout << var1; break;
case 2:  cout << var2; break;  // also blech!
}

However, using an array, you can simply use the variable as an "index" to select the appropriate variable:

cout << var[which];

[whOOper]

Ok that clarified it a little bit, but could you give an example with an array in a math operation and thanks for the answer.

[Disch]

I did, well, maybe not a mathmatical operation, but I showed several statements using an array (comparison, assignment, output with cout)

But okay:

int numbers[3];   // make an array with 3 elements

numbers[0] = 5;  // set the first two elements to 5 and 6, respectively
numbers[1] = 6;

// sum the first two elements, store result in the last element
numbers[2] = numbers[0] + numbers[1];

That's not a very practical thing to do, of course.

Anyway the index of the variable you want to use goes in the brakets. That's all there is to it.

[whOOper]

Thank you for clearing that up for me that really helped.