Transcript Data structure - Pui Ching Middle School

Programming Languages
Classification and distinctive features

Procedural Language



A term used in contrast to declarative language to describe a
language where the programmer specifies an explicit sequences of
steps to follow to produce a result.
Common procedural languages include Basic, Pascal and C.
Declarative Language


Declarative languages describe relationships between variables in
terms of functions or inference rules and the language executor
(interpreter or compiler) applies some fixed algorithm to these
relations to produce a result.
Common declarative languages include logic programming
languages such as Prolog
Classification and distinctive features

Object-oriented Language


A programming languages and techniques based on the concept of
an "object" which is a data structure (abstract data type)
encapsulated with a set of routines, called "methods" which
operate on the data. Operations on the data can only be performed
via these methods, which are common to all objects, which are
instances of a particular "class".
Common declarative languages include C++ and Java.
Classification and distinctive features

Visual Programming



Visual programming environments provides graphical or
iconic elements, which can be manipulated by the user in an
interactive way according to some specific spatial grammar
for program construction.
Common declarative languages include Visual Basic and
Visual C++.
Query Language

A language in which users of a database can (interactively)
formulate requests and generate reports. The best known is
SQL
Tracing simple programs in C++
A simple C++ program
#include <iostream.h>
preprocessor directive(s)
main() {
// A simple C++ program
int x, y, sum;
cout << "A program which adds two integers\n";
cout << "Enter 1st integer: ";
cin >> x;
cout << "Enter 2nd integer: ";
cin >> y;
sum = x + y;
cout << "Sum is " << sum << endl;
return 0;
}
program body
syntax of C++





The preprocessor directive ‘#include <iostream.h>’ can be found in a
lmost all C++ programs.
It provides subprograms to process standard input and standard output.
Use cin for standard input and cout for standard output.
Declarative statements can be put in anywhere of the program body.
Use a pair of double quotation marks (") to enclose a string.
Special characters:

\t (horizontal tab)

\n (newline character)

\\ (the backslash \)

\" (the double quotation mark ")
Data types, variables and
variable assignment


Variables are case-sensitive.
Common simple data types











int (integer)
short (16-bit integer)
long (32-bit integer)
char (character)
float (single precision floating-point number)
double (double precision floating-point number)
The type modifier unsigned indicates that the variable cannot hold neg
ative numbers.
The reserved word typedef is used to define a new data type.
C++ uses the equal sign (=) for assignment, e.g. ‘x = 4;’. (Use ‘==’ as
‘equal to’ in C++.)
Initialisation can be done in the declarative statements, e.g. ‘int x = 4;’
Mixed-mode assignment is possible: