Answers of Concepts of Programming Languages Chapter 5

1. Whether the names are case sensitive and whether the special words of languages are reserved words or keywords
2. it can harm the readibility of the program
3. Because the ability to redefine keywords can be confusing
4. Variables accessing the same memory location
5. In C++ reference, aliases are used in the union types
6. l-value is the address of a variable, while r-value is the value of the variable

Problem set
1. all valid except _Student and 123Student
2. l-value is the address of a variable.
   Example of the error ->  "   = 1+2; "
3.
4. Type declaration of a variable is necessary because it determines the range of values it can store and the set of operations it can use
   int type in Java ranges a value range of -2147483648 to 2147483647