Identifier Forms, Typeless Languages, Scoping In Javascript And C. Assignment 5

NYI NYI MOE HTET COMP 333 ASSIGNMENT 5 1. Which of the following identifier forms is most readable? Support your decision. SumOfSales sum_of_sales SUMOFSALES "sum_of_sales" is the most readable due to its clarity, word separation, and consistency with common naming conventions. The underscores make it easier to read and understand the words, and snake_case is widely used in programming languages such as Python. 2. Some programming languages are typeless. What are the obvious advantages and disadvantages of having no types in a language? A typeless programming language provides flexibility and expressiveness but may lead to runtime errors due to lack of type checking during compilation. Typeless declarations can also impact code readability and maintainability, making it harder to understand variable types without documentation. 3. Dynamic type binding is closely related to implicit heap-dynamic variables. Explain this relationship. In dynamic type binding, a variable's type is determined during runtime. Implicit heap-dynamic variables involve automatic memory management on the heap without explicit programmer intervention. In dynamically typed languages, variables with changing types are commonly stored on the heap. When a variable's type changes dynamically, the system may need to allocate or deallocate memory on the heap, highlighting the connection between dynamic type binding and the implicit management of heap-dynamic variables. 4. Consider the following JavaScript skeletal program: // The main program var x; function sub1() { var x; function sub2() { ... } } function sub3() { ... } Assume that the execution of this program is in the following unit order: main calls sub1 sub1 calls sub2 sub2 calls sub3 1) Assuming static scoping, in the following, which declaration of x is the correct one for a reference to x? 1. sub1 2. sub2 3. sub3 2) Repeat part a, but assume dynamic scoping. Static scoping: In sub1, the declaration of x in sub1 is the correct reference to x. In sub2, the declaration of x in sub1 is the correct reference to x. In sub3: the declaration of x in main is the correct reference to x. Dynamic scoping: The declaration of x in sub1 is the correct reference to x for sub1, sub2 and sub3. 5. Assume the following JavaScript program was interpreted using static-scoping rules. What value of x is displayed in function sub1? Under dynamic-scoping rules, what value of x is displayed in function sub1? var x; function sub1() { document.write("x = " + x + ""); } function sub2() { var x; x = 10; sub1(); } x = 5; sub2(); Under static-scoping, 5 will be displayed. Under dynamic-scoping, 10 will be displayed. 6. Consider the following JavaScript program: var x, y, z; function sub1() { var a, y, z; function sub2() { var a, b, z; ... } ... } function sub3() { var a, x, w; ... } List all the variables, along with the program units where they are declared, that are visible in the bodies of sub1, sub2, and sub3, assuming static scoping is used. Sub1: a(sub1), y(sub1), z(sub1), x(main) Sub2: a(sub2), b(sub2), z(sub2), x(main), y(main) Sub3: a(sub3), x(sub3), w(sub3), y(main), z(main) 7. Consider the following skeletal C program: void fun1(void); /* prototype */ void fun2(void); /* prototype */ void fun3(void); /* prototype */ void main() { int a, b, c; ... } void fun1(void) { int b, c, d; ... } void fun2(void) { int c, d, e; ... } void fun3(void) { int d, e, f; ... } Given the following calling sequences and assuming that dynamic scoping is used, what variables are visible during execution of the last function called? Include with each visible variable the name of the function in which it was defined. 1) main calls fun1; fun1 calls fun2; fun2 calls fun3. 2) main calls fun1; fun1 calls fun3. 3) main calls fun2; fun2 calls fun3; fun3 calls fun1. 4) main calls fun3; fun3 calls fun1. 5) main calls fun1; fun1 calls fun3; fun3 calls fun2. 6) main calls fun3; fun3 calls fun2; fun2 calls fun1. 1) d, e, f fun3 c fun2 b fun1 a main 2) d, e, f fun3 b, c fun1 a main 3) b, c, d fun1 e, f fun3 a main 4) b, c, d fun1 e, f fun3 a main 5) c, d, e fun2 f fun3 b fun1 a main 6) b, c, d fun1 e fun2 f fun3 a main