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Manipulating Integer/Double Variables
Integers/Doubles are two popular number data types that are mostly used for counting, summing,
averaging and other mathematical calculations. There are many things
you can do with numbers, especially when using them in conjunction with
loops. You probably already know the basics, so this section will
teach you some cool stuff that you can do with these data types.
The
first thing to note is that, unlike strings, integers don't require a
specific library for them to function. To
avoid repetition, here is an example that uses integers for counting:
#include <iostream.h>
void main()
{
int counter=0;
int user_input=0;
cout << "Enter Max Number" << endl;
cin >> user_input;
for (counter; counter <= user_input; counter++)
{
cout << counter << endl;
}
} What
this code does is that it inputs a number from the user. The For
loop then keeps on executing until counter (which is 0) is
less than or equal to the user input. Each number is then displayed
on its own line going from 0 up until the value entered by the
user. You'll see this example a lot, even in your own coding.
Counters are very important when it comes to programming and using loops
in general.
You'll find that it is easy and fun exploring the world of integers,
doubles and
counters. Therefore, to help you out with your journey, here are
some tips for formatting your output. Note that these are part of
the iostream library so you must state the library at the top of
your code.
| Function |
Description |
Example |
| width() |
sets
a specific width for a variable |
cout << 1234567890 << endl;
cout.width(10);
cout << 123 << endl;
cout.width(5);
cout << 456 << endl;
Displays:
1234567890
123
456
|
| precision() |
sets
the number of decimal places for a number |
double
answer=2.32*4.77;
cout.precision(2);
cout << answer << endl;
Displays:
11.07 instead of 11.0664
|
| setf() |
determines
alignment of output. Used in conjunction with width()
to align output in its field. The function accepts the
following constants: left, right (default).
Note that if you want to change alignment from left to right,
you'll have to unset the default left alignment with this
line: cout.unsetf(ios::left); |
cout.setf(ios::left);
cout << 1234567890 << endl;
cout.width(10);
cout << 123 << endl;
cout.width(5);
cout << 456 << endl;
Displays:
1234567890
123
456
instead of:
1234567890
123
456
|
Note that
the functions width() and precision() have to be entered before
each output that is to be formatted. On the other hand, setf()
needs to be set only once.
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