Constants - sheerazwalid/COMP-I GitHub Wiki
Constant literals
The number 16 in the following code is called a literal constant.
k = 16;
The following illustrates how to represent the number 16 using three different bases.
16 // decimal -- base 10
020 // octal -- base 8
0x10 // hexadecimal -- base 16
cout << 16; // Prints "16".
cout << 020; // Prints "16".
cout << 0x10; // Prints "16".
WARNING: if you precede an integer literal with a zero, the compiler assumes it's an octal value. This could lead to bugs.
Representing constants with identifiers
Constants are named in 2 different ways. First, there is the old fashioned preprocessing directive from the C language.
#define PI 3.1415926
double area = PI * r * r;
Second, there is the newer C++ approach using the keyword const.
const double pi = 3.1415926;
double area = pi * r * r;
Constants defined in the preprocessing step are often in ALL CAPS.