what is the [i] mean in this code?

[killertcell]

I was trying to finish a programming exercise, but i gave up and used the answer. but what does the [i] mean in the arrays in this code?

#include <iostream>
#include <cctype>
#include <string>
 
struct bop {
char fullname[40]; // real name
char title[20]; // job title
char bopname[40]; // secret BOP name
int preference; // 0 = fullname, 1 = title, 2 = bopname
};
 
int main()
{
 
using namespace std;
bop Programmer[5] = {
"Alex Ignatkov","System Analyst","IGNAT",2,
"Bob Emerson","Manager","BOBZ",1,
"John Doe","Programmer","DOE",0,
"Bob Evans","Debugger","EVS",2,
"Nick Johns","Tester","NJ",1};
 
char choice;
 
cout << "a. display by name       b. display by title\n";
cout << "c. display by bopname        d. display by preference\nq. quit\n";
 
do
{
    cout << "\nEnter your choice: ";
    cin >> choice;
    choice = tolower(choice);
 
    if (choice != 'a' && choice != 'b' && choice !='c' && choice !='d')
        continue;
    else for (int i=0; i<5; i++)
    {
        switch (choice)
        {
            case 'a': cout << "\n" << Programmer [i].fullname;break;
            case 'b': cout << "\n" << Programmer [i].title;break;
            case 'c': cout << "\n" << Programmer [i].bopname;break;
            case 'd': switch (Programmer[i].preference)
                      {
                        case 0: cout << "\n" << Programmer [i].fullname;break;
                        case 1: cout << "\n" << Programmer [i].title;break;
                        case 2: cout << "\n" << Programmer [i].bopname;break;
                        }
        }
    }
 
} while (choice != 'q');
 
cout << "\nBye!\n";
 
cin.get();
cin.get();
return 0;
}

[o3hC5Di1]

Hi there,

In this piece of code:
for (int i=0; i<5; i++) // line36
i is defined.

During this for loop, i functions as a counter which starts at value 0 and increments by one until it is 4 (smaller than 5).

Thus every iteration i will be a higher number allowing you to traverse or loop through an array's elements.
The first iteration Programmer[0] will be used, then Programmer[1] and so on and so forth.

Hope that helps.

All the best,
NwN

[Akshit]

if you mean "i" then its a counter

if you mean "Programmer [i]" then its (i+1)th programmer's data name.

Hope you understand in short.If not then let me know.I can write more about it.

[Volatile Pulse]

Specifically to this case, i is used to represent the index of the array, or "i". Since it was so common to see this, most programmers just use i in their for loops, but technically, any variable name works. In more complex programs, I change the name of i to something more descriptive, like menuOption, or something that explains what in my array I'm looking for.

[zb0S216C]

It's called the sub-script operator. It's used to obtain an element from an array. The expression that sits between the opening and closing bracket ([...]) must evaluate at an integral value. This integral value is called an index. The index for the first element is zero, and the index for the last is N - 1, where N is the array length.

Technical Extension:
The sub-script operator performs 2 secret operations:

- Dereference
- Addition

The address of the first element is offset by the index specified within the sub-script operator. The resulting address is dereferenced; thus yielding the element at the specified index. In other words, the sub-script operator is equal to this:

*(array_ + index_);

The parentheses here are necessary, because the asterisk (*) has a higher precedence than addition.

_Wazzak

[Volatile Pulse]

Where do you learn this kind of stuff? I understand why it's relevant in some cases, but this isn't something I can just recite off of the top of my head (I also believe this is a little more of an explanation than what the OP had asked for). Thanks for sharing though.

[zb0S216C]

I learn from technical blogs, Stack Overflow, FAQs, this site, etcetera.

Volatile Pulse wrote:

"I also believe this is a little more of an explanation than what the OP had asked for"

Hence the "Technical Extension" header.

_Wazzak

[ResidentBiscuit]

Just lots of reading and working with it and becomes second nature. I think Moschops has an article about pointers that discusses the concept Framework just showed.

[o3hC5Di1]

Just wanted to drop a quick "Thanks!" to Framework - very informative as always.

All the best,
NwN