How many keywords in c plus plus and what are they?

The const keyWord is the antonym of variable. While a variable is a volatile identifier and can change its value at any time, a constant identifier is non-volatile and must be assigned a value at the point of instantiation. Whenever you declare a constant you are allowing the compiler to assure you that the value will never change, whether purposely or by programming error. By allowing the compiler to assure constance, you do not need to manually check if the value has been altered. As with many other things in C++, the more responsibility you hand to the compiler, the more robust your programs will be.