What are C++ Integer Constants?

Integer constants are constant data elements that have no fractional parts or exponents. They always begin with a digit. You can specify integer constants in decimal, octal, or hexadecimal form. They can specify signed or unsigned types and long or short types.

In C++ you can use the following code to create an integer constant −

#include<iostream>
using namespace std;
int main() {
   const int x = 15; // 15 is decimal integer constant while x is a constant int.
   int y = 015; // 15 is octal integer constant while y is an int.
   return 0;
}

You can find the complete grammar to specify integer constants on https://msdn.microsoft.com/en-us/library/00a1awxf.aspx.