CSCICMPE 4341 Topic Programming in Python Review Exam

CSCI/CMPE 4341 Topic: Programming in Python Review: Exam I Xiang Lian The University of Texas – Pan American Edinburg, TX 78539 lianx@utpa. edu

Review • Chapters 1 ~ 4 in your textbook • Lecture slides • In-class exercises 2

Review • Multiple Choice • True/False Statements • Programming – Find bugs – Write the code • Bonus Question (20 extra points) 3

Chapter 1: Introduction to Python • • • Basic components in a computer system The evolution of programming language Structured programming Object-oriented programming Can you list several differences between C++ and Python? 4

Python • Python is a scripting language – It is not compiled as an executable file • Python – Structured programming • Divide and conquer – Object-oriented programming • Class and object – Data encapsulation – Inheritance – Polymorphism 5

Chapter 2: Basic Concepts in Python Programming • Commonly used Python rules/functions – – – # print() input() int() id() type() • Escape characters • Arithmetic operators and their precedence • String formatting 6

First Program in Python: Printing a Line of Text • Python – The # symbol "//" or "/* … */" is used in C/C++/Java • Used to denote a single line comment – The print function • • "printf" or "cout" is used in C/C++ "System. out. println(. . . )" in Java • Used to send a stream of text to be output to the user • Executing – Saving as a file • Type code into a. py file and save it • To run it type python file. Name. py – Executing code • Type python in the command line • Runs the python interpreter 7

Examples of Escape Characters 8

Arithmetic Operators • Symbols – – – * / % ** // # multiply # divide # modulus # exponential # floor division • Order – Operators are done in order of parenthesis, exponents, multiply and divide (left to right), and lastly add and subtract (left to right) 9

Precedence of Arithmetic Operators 10

# Fig. 2. 19: fig 02_19. py # String formatting. integer. Value = 4237 print ("Integer ", integer. Value) print ("Decimal integer %d" % integer. Value) print ("Hexadecimal integer %xn" % integer. Value) Outline Fig 02_19. py float. Value = 123456. 789 print ("Float", float. Value) print ("Default float %f" % float. Value ) print ("Default exponential %en" % float. Value ) print ("Right justify integer (%8 d)" % integer. Value) print ("Left justify integer (%-8 d)n" % integer. Value ) string. Value = "String formatting" print ("Force eight digits in integer %. 8 d" % integer. Value ) print ("Five digits after decimal in float %. 5 f" % float. Value ) print ("Fifteen and five characters allowed in string: " ) print ("(%. 15 s) (%. 5 s)" % ( string. Value, string. Value ) ) 2002 Prentice Hall. All rights reserved.

Chapters 3 & 4: Control Structures • The syntax of basic sequence, selection, and repetition structures in Python • Selection – if, if/else, if/else – Empty statement: pass • Counter-controlled and sentinel-controlled repetition – while, for – break, continue • Augmented assignment • Logical operators 12

Control Structure • 3 control structures – Sequential structure • Built into Python – Selection structure • The if statement • The if/else statement – Repetition structure • The while repetition structure • The for repetition structure 13

Syntax of Control Structure total = total + Grade counter = counter + 1 if Grade>=60: print ("Passed") else: print ("Failed") 14

Syntax of Control Structure (cont'd) if Grade>=90: print ("A") else: if Grade>=80: print ("B") else: if Grade >=70: print ("C") else: if Grade>=60: print ("D") else: print ("F") if Grade>=90: print ("A") elif Grade>=80: print ("B") elif Grade >=70: print ("C") elif Grade>=60: print ("D") else: print ("F") 15

Syntax of Control Structure (cont'd) Product = 1 while Product < 1000: Product = 2* Product for Product in range(1, 1000): Product = 2* Product 16

for Repetition Structure 17 • The for loop – Function range is used to create a list of values [0, integer-1] – range ( integer ) » Values go from 0 to given integer [integer 1, integer 2 -1] – range ( integer 1, integer 2) » Values go from first up to second integer [integer 1, integer 2 -1] – range ( integer 1, integer 2, integer ) » Values go from first up to second integer, but increases in intervals of the third integer – The loop will execute as many times as the value passed – for counter in range ( value ): 17

break and continue Statements • The break statement – Used to make a loop stop looping – The loop is exited and no more loop code is executed • The continue statement – Used to continue the looping process – All following actions in the loop are not executed • But the loop will continue to run 18

Logical Operators • Operators – and • Evaluates to true if both expressions are true – or • Evaluates to true if at least one expression is true – not • Returns true if the expression is false • Not required in any program 19

and Logical Operator 20

or Logical Operator 21

not Logical Operator 22

Chapter 5: Functions • Modules and pre-defined functions – import module. Name – math • • • math. floor () math. ceil () math. cos () math. pow () … – random • random. randrange() • Syntax of user-defined functions • Recursive function • Default arguments 23

Module math Functions • Module – Contains function definitions and other elements • All of which are related in some way – Calling a function • function. Name ( argument 1, argument 2 ) – The import keyword is used to include a module – Invoking functions from a module • Use the module name followed by the dot operator (. ) • module. Name. function. Name( argument ) 24

Random-Number Generation • The random module – Used to generate a random number for the programmer – Function randrange • Generates a number from the first argument up to, but not including, the second argument • Each number in the range has the same likelihood of being selected by the function 25

Examples of Floor and Ceiling • floor function: – – math. floor(2. 10) = 2 math. floor(2. 00) = 2 math. floor(1. 90) = 1 math. floor(1. 80) = 1 • ceil function: – – math. ceil(0. 00) = 0 math. ceil(0. 10) = 1 math. ceil(0. 20) = 1 math. ceil(0. 30) = 1 26

User-Defined Functions • Definitions – Functions must be defined before they are used – def function. Name ( param. List ): • function. Name is a valid identifier • param. List is a comma separated list of parameters received • The actions of the functions then follows – They should all be indented appropriately – The actions are also called the block or the function body 27

Recursion • Method that calls itself • A recursive method solves only a simple problem (base case) • For any thing other than the base case, it calls itself with a slightly simpler problem – Eventually it becomes the base case for which it knows the answer 28

Default Arguments • Function arguments – Functions may commonly receive a particular value type – When this is true a default argument can be set • Must appear to the right of any other arguments – A default value can also be set • If passes a value then the default value is overridden 29

Good Luck! Q/A