File Name: static and dynamic scope in programming language .zip
Computer Science Stack Exchange is a question and answer site for students, researchers and practitioners of computer science. It only takes a minute to sign up. My teacher has provided the following pseudo-code, and says that the output using static scope is 1 2 3 , but the output using dynamic scope is 2 3 4. Which variable we use in Static Scope? By the way: C has static scope rules. What is static scope? Static scope refers to scope of a variable is defined at compile time itself that is when the code is compiled a variable to bounded to some block scope if it is local, can be bounded to entire Main block if it is global.
What is dynamic scope in Programming Languages? Dynamic scope refers to scope of a variable is defined at run time rather than at compile time. Perl language allows dynamic scoping. So, if we use dynamic scoping output will be 2,3,4. For clear information check this link static scope and dynamic scope with examples. Therefore there is only one 'c' in the program, the global one.
When the program is run, this 'c' is first initialized to 3, then the value 3 is overwritten in main with 4, which is why the output of fun2 is '1 2 4'. THEN we can say that the output of fun2 should be '1 2 3' under static scoping as in C versus '1 2 4' under dynamic scoping. Each procedure that is invoked contains a link the dynamic link to the invoking procedure.
When the procedure is finished, this link is used to return to the invoking procedure. In a language using dynamic scoping,the dynamic link is also used to lookup the 'scope' of the variables. That means that in the example fun2 is invoked by fun1.
In a static scoped also called lexical scoped language the dynamic link is only used to find the return address when the procedure is finished. A second link called the static link is defined to find the scope of the variables. In the example all three functions fun1, fun2 and main are defined on the same level. All three of them will have a static link pointing to the global level. Sign up to join this community. The best answers are voted up and rise to the top. What are differences between Static Scope and Dynamic Scope?
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I added one missing int to variable C, after edit. Sorry if I changed question too much, but it was off topic as only checking code. Amareswar Reddy Amareswar Reddy 41 2 2 bronze badges. Copying without indication that the material has been copied, or without proper attribution, is frowned upon by our community. Please consult our guidelines on crediting your sources and edit your answer so it complies with those guidelines. Thank you! Please do look at our guidelines.
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The following program fragment is written in a programming language that allows global variables and does not allow nested declarations of functions. If the programming language uses dynamic scoping and call by name parameter passing mechanism, the values printed by the above program are. In general, the effect of pass-by-name is to textually substitute the argument expressions actual parameters in a procedure call for the corresponding parameters formal parameters in the body of the called procedure. Direct Substitution of actual parameters in the place of formal parameter in the called procedure. Again, Once we substitute Actual arguments in the place of formal parameters in the called function, for those variables in the actual arguments, Environment of caller function will be applicable. And in function P, in the 4th statement i.
Traditional treatment of scoping in programming languages considers two opposite semantics: static scoping, where the scope of a binding is a block of program text, and dynamic scoping, where a binding is in effect during the whole reduction of an expression to a value. Static scoping and dynamic scoping are however but two points in the design space of scoping mechanisms. As a result, most proposed language mechanisms that rely on some notion of scoping, such as variable bindings of course, but also more exotic ones like aspects and mixin layers, adopt either one or the other semantics. As it turns out, these two semantics are sometimes too extreme, and a mixture of both is needed. We present a general scoping model that simply expresses static and dynamic scoping, and that goes further by allowing fine-grained exploration of the design space of scoping.
Computer Science Stack Exchange is a question and answer site for students, researchers and practitioners of computer science. It only takes a minute to sign up. My teacher has provided the following pseudo-code, and says that the output using static scope is 1 2 3 , but the output using dynamic scope is 2 3 4. Which variable we use in Static Scope?
In computer programming , the scope of a name binding —an association of a name to an entity, such as a variable —is the part of a program where the name binding is valid, that is where the name can be used to refer to the entity. In other parts of the program the name may refer to a different entity it may have a different binding , or to nothing at all it may be unbound. The scope of a name binding is also known as the visibility of an entity, particularly in older or more technical literature—this is from the perspective of the referenced entity, not the referencing name.
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