Page 173 - DCAP507_SYSTEM_SOFTWARE

Unit 10: Programming Languages Concept (I)

Notes
Example:
Char *C; Pointer-variable

&C - C is a variable, and &C is the address in which the value of C is stored.
*C - content of the location

10.6.2 Accessing of Label Variable

Labels are mainly used with a statement, so that the statement can be referenced in future during
the execution.
Syntax : Label = prefix:
PASCAL: A label-prefix is a non-zero positive unsigned integer. The
maximum size can be 4 digits.

C : A label-prefix can be any identifier but must be unique.

Task Illustrate how to declare and refer a pointer type variable.

Self Assessment

Fill in the blanks:
13. A .......................... is an identifier, which refers to computer memory space where some
value can be stored.

14. A .......................... is a variable that points at, or refers to, another variable.
15. .......................... are mainly used with a statement, so that the statement can be referenced in
future during the execution.

10.7 Summary

 A language consists of all the symbols, characters and usage rules that permit people to
communicate with each other.
 The programming languages are said to be low or high or very high or natural, depending
on how far these are from the internal architecture of the machine or how close they are to
the user as far as the convenience of the user is concern.

 High level languages basically consist of English like instructions rather than mnemonic
codes or binary digits of specific computer, so this language is easier to learn than assembly
language.
 The kind of data that variables may hold is called as Data type.
 All high level languages share a set of intercepted structure of data structure that generates
the languages. These normal data structures are strings, arrays, I/O, Stacks, Queues, Linked
Lists, Trees, Graphs, Hash tables, and Vectors.
 A linker or loader's first main task is storage allocation. Once storage is assigned, the
linker can carry on to following stages of symbol binding and code fixups.

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