Python/C3/Conditionals/English-timed - Revision history

PoojaMoolya at 06:50, 27 March 2017

2017-03-27T06:50:07Z

PoojaMoolya at 11:24, 20 February 2017

2017-02-20T11:24:02Z

PoojaMoolya at 05:31, 7 August 2014

2014-08-07T05:31:36Z

Gaurav at 09:37, 10 July 2014

2014-07-10T09:37:22Z

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Sneha at 09:28, 22 March 2013

2013-03-22T09:28:05Z

Sneha at 05:23, 21 March 2013

2013-03-21T05:23:24Z

Sneha at 12:16, 18 March 2013

2013-03-18T12:16:49Z

Sneha at 12:10, 18 March 2013

2013-03-18T12:10:43Z

Minal: Created page with '{| border=1 !Visual Cue !Narration |- | 0:01 | Hello friends and Welcome to the tutorial on 'Conditionals'. |- | 0:05 | At the end of this tutorial, you will be able to, # Use…'

2013-01-02T12:05:19Z

Created page with '{| border=1 !Visual Cue !Narration |- | 0:01 | Hello friends and Welcome to the tutorial on 'Conditionals'. |- | 0:05 | At the end of this tutorial, you will be able to, # Use…'

New page

{| border=1
!Visual Cue
!Narration
|-
| 0:01
| Hello friends and Welcome to the tutorial on 'Conditionals'.

|-
| 0:05
| At the end of this tutorial, you will be able to,

# Use if/else blocks.
# Use if/elif/else blocks.
# Use the Ternary conditional statement - C if X else Y.

|-
| 0:25
| To begin with let us start ipython,

|-
|0:29
|So type ipython in the terminal

|-
| 0:36
| Whenever we have two possible states that can occur depending on a a certain condition, we can use if/else construct in Python.

|-
| 0:45
| For example, say, we have a variable <tt>a</tt> which stores integers and we are required to find out whether <tt>a</tt> is even or odd.

|-
| 0:52
| Let's say the value of <tt>a</tt> is 5.

|-
|0:55
|So type a=5

|-
| 0:59
| In such a case we can write the if/else block as

|-
|1:04
|In command line if a percentage 2 == 0 colon

print in double quotes Even
else colon
print in double quotes Odd

|-
| 1:37
| If <tt>a</tt> is divisible by 2, i.e., the result of "a modulo 2" is 0, it prints "Even", otherwise it prints "Odd".

|-
|1:51
| Note that in such a case, only one of the two blocks gets executed depending on whether the condition is <tt>True</tt> or <tt>False</tt>.

|-
|1:58
| There is a very important syntactic element to understand here.

|-
|2:03
| Every code block begins with a line that ends with a <tt> colon</tt>, in this example the <tt>if</tt> and the <tt>else</tt> lines.

|-
|2:15
| Also, all the statements inside a code block are intended by 4 spaces.

|-
|2:21
| Hitting enter twice, ends the code block.

|-
|2:25
| The if/else blocks work for a condition, which can take one of two states.

|-
|2:31
| But what do we do for conditions, which can take more than two states?

|-
| 2:38
| Python provides if/elif/else blocks, for such conditions.

|-
| 2:47
| For example.

|-
| 2:49
| We have a variable <tt>a</tt> which holds integer values.

|-
|2:52
| We need to print "positive" if <tt>a</tt> is positive, "negative" if it is negative or "zero" if it is 0.

|-
|3:04
| Let us use if/elif/else ladder for it.

|-
|3:09
| For the purposes of testing our code let us assume that the value of a is -3

|-
|3:16
|Type a = -3

if a greater than 0 colon
print in double quotes positive
elif a less than 0 colon
print in double quotes negative
else colon
print in double quotes zero

|-
| 4:17
| All the syntax and rules as said for if/else statements hold the same.

|-
| 4:24
| The only addition here is the <tt>elif</tt> statement which can have another condition of its own.

|-
| 4:30
| Here too, exactly one block of code is executed -- the block of code which first evaluates to <tt>True</tt>.

|-
| 4:41
| Even if there is a situation where multiple conditions evaluate to True, all the subsequent conditions other than the first one, which evaluates to True, are neglected.

|-
| 4:51
| Consequently, the else block gets executed if and only if all the conditions evaluate to False.

|-
| 4:59
| Also, the <tt>else</tt> block in both if/else statement and if/elif/else is optional.

|-
| 5:08
| We can have a single if statement or just if/elif statements without having else block at all.

|-
| 5:17
| Also, there can be any number of elif's within an if/elif/else ladder.

|-
| 5:26
| For example

|-
|5:28
|Type if user == in single quotes admin colon
elif user == in single quotes moderator colon
elif user == in single quotes client colon

|-
| 5:47
| Note that there are multiple elif blocks and there is no else block.

|-
| 5:53
| Pause the video here, try out the following exercise and resume the video.

|-
| 5:57
| '''Given a number, num. Write an if else block to print num, as is,'''

|-
| 6:05
| if it is divisible by 10, else print 10 into num.

|-
| 6:12
| The solution is on your screen.

|-
|6:14
| if num modulo 10 == 0 colon
print num
else colon
print 10 star num

|-
| 6:29
| In addition to these conditional statements, Python provides a very convenient ternary conditional operator.

|-
| 6:35
| Let us take the following example where we read the marks from a data file which is obtained as a string as we read a file.

|-
| 6:43
| The marks can be in the range of 0 to 100 or 'AA' if the student is absent.

|-
| 6:51
| In such a case, to obtain the marks as an integer, we can use the ternary conditional operator.

|-
| 6:58
| Let us say the string score is stored in score underscore str variable

|-
|7:05
|So type score underscore str = in single quotes AA

|-
| 7:13
| Now let us use the ternary conditional operator

|-
|7:19
|Type score = int within bracket score underscore str if score underscore str exclamation = in single quotes AA else 0

|-
| 7:54
| '''Given a number, num. Write a ternary operator to print num, as is,'''

|-
| 8:01
| if it is divisible by 10, else print 10 star num.

|-
| 8:08
| The solution is on your screen.

|-
| 8:11
| print num if num modulo 10 == 0 else 10 star num

|-
| 8:19
| Moving on, there are certain situations where we will have no operations or statements within a block of code.

|-
| 8:27
| For example, we have a code where we are waiting for the keyboard input.

|-
| 8:32
| If the user enters "c", "d" or "x" as the input, we would perform some operation; nothing otherwise.

|-
| 8:42
| In such cases "pass" statement comes very handy

|-
| 8:49
| '''a = raw underscore input Enter 'c' to calculate and exit, 'd' to display the existing'''

|-
| 9:04
| results exit and 'x' to exit and any other key to continue
|-
| 9:12
| '''if a == in single quote c colon'''

|-
| 9:18
| '''elif a == in single quote d colon'''

|-
| 9:23
| '''elif a == in single quote x colon'''

|-
| 9:29
| '''else colon'''

|-
| 9:32
| pass

|-
| 9:35
| In this case "pass" statement acts as a place holder for the block of code.

|-
| 9:41
| It is equivalent to a null operation.

|-
| 9:45
| It literally does nothing.

|-
| 9:46
| It can used as a place holder when the actual code implementation for a particular block of code is not known yet but has to be filled up later.

|-
| 9:56
| This brings us to the end of the tutorial.

|-
| 9:59
| In this tutorial, we have learnt to, 1. Understand the conditional statements in Python.

|-
| 10:04
| 2. Use if/else statement.

|-
| 10:06
| 3. Use if/elif/else statement.

|-
| 10:09
| 4. Apply the ternary conditional statement - C if X else Y.

|-
| 10:14
| 5. Use "pass" statement.

|-
| 10:18
| Here are some self assessment questions for you to solve

|-
| 10:21
| 1. Use conditional statements for the following.

|-
| 10:23
| Given a variable <tt>time</tt>, print <tt>Good Morning</tt> if it is less than 12, otherwise print <tt>Hello</tt>.

|-
| 10:30
| 2. Convert the if else ladder below into a ternary conditional statement.

|-
| 10:39
| x = 20
if x greater than 10 colon
print x multiply by 100
else colon
print x

|-
| 10:48
| And now look at the answers,

|-
| 10:52
| 1. We can use the if/else statements as
<nowiki>if time less than 12 colon</nowiki>
print in double quotes Good Morning
else colon
print in double quotes Hello

|-
| 11:06
| 1. The if else ladder can be converted to a ternary conditional statement as
print x multiply by 100 if x greater than 10 else x

|-
| 11:17
| Hope you have enjoyed this tutorial and found it useful.

|-
| 11:20
| Thank you!

|}

@@ Line 284: / Line 284: @@
 |-
 | 09:45
-| It literally does nothing.
+| It literally does nothing. It can used as a place holder when the actual code implementation for a particular block of code is not known yet but has to be filled up later.
-−
-|-
-| 09:46
-| It can used as a place holder when the actual code implementation for a particular block of code is not known yet but has to be filled up later.
 |-

@@ Line 9: / Line 9: @@
 | 00:05
 | At the end of this tutorial, you will be able to,
 Use if/else blocks.
-# Use if/else blocks.
+Use if/elif/else blocks.
-# Use if/elif/else blocks.
+Use the Ternary conditional statement - C if X else Y.
-# Use the Ternary conditional statement - C if X else Y.
 |-
@@ Line 45: / Line 44: @@
 |01:04
 |In command line if a percentage 2 == 0 colon
 print in double quotes Even
-    		print in double quotes Even
+else colon
-	   else colon
+print in double quotes Odd
-    		print in double quotes Odd
 |-
@@ Line 109: / Line 107: @@
 |03:16
 |Type	a = -3
 if a greater than 0 colon
-	print within double quotes positive
+print within double quotes positive
 elif a less than 0 colon
- print in double quotes negative
+print in double quotes negative
-	else colon
+else colon
-	    print within double quotes zero
+print within double quotes zero
 |-
@@ Line 156: / Line 153: @@
 |05:28
 |Type 	if user == in single quotes admin colon
-	elif user == in single quotes moderator colon
+elif user == in single quotes moderator colon
-	elif user == in single quotes client colon
+elif user == in single quotes client colon
 |-
@@ Line 182: / Line 179: @@
 |06:14
 |if num modulo 10 == 0 colon
-	print num
+print num
-      else colon
+else colon
-	print 10 star num
+print 10 star num
 |-
@@ Line 299: / Line 296: @@
 |-
 | 09:59
-| In this tutorial, we have learnt to, 1. Understand the conditional statements in Python.
+| In this tutorial, we have learnt to, Understand the conditional statements in Python.
 |-
 | 10:04
-| 2. Use if/else statement.
+|Use if/else statement.
 |-
 | 10:06
-| 3. Use if/elif/else statement.
+| Use if/elif/else statement.
 |-
 | 10:09
-| 4. Apply the ternary conditional statement - C if X else Y.
+| Apply the ternary conditional statement - C if X else Y.
 |-
 | 10:14
-| 5. Use "pass" statement.
+| Use "pass" statement.
 |-
@@ Line 323: / Line 320: @@
 |-
 | 10:21
-| 1. Use conditional statements for the following.
+| Use conditional statements for the following.
 |-
@@ Line 331: / Line 328: @@
 |-
 | 10:30
-| 2. Convert the if else ladder below into a ternary conditional statement.
+| Convert the if else ladder below into a ternary conditional statement.
 |-
 | 10:39
 | x = 20
-  if x greater than 10 colon
+if x greater than 10 colon
-   print x multiply by 100
+print x multiply by 100
-  else colon
+else colon
-   print x
+print x
 |-
@@ Line 347: / Line 344: @@
 |-
 | 10:52
-| 1. We can use the if/else statements as
+| We can use the if/else statements as
-   if time less than 12 colon
+if time less than 12 colon
-   print in double quotes Good Morning
+print in double quotes Good Morning
-  else colon
+else colon
-   print in double quotes Hello
+print in double quotes Hello
 |-
 | 11:06
-| 1. The if else ladder can be converted to a ternary conditional statement as
+|The if else ladder can be converted to a ternary conditional statement as print x multiply by 100 if x greater than 10 else x
-   print x multiply by 100 if x greater than 10 else x
 |-

@@ Line 1: / Line 1: @@
 {| border=1
-!Visual Cue
+!Time
 !Narration
 |-

@@ Line 111: / Line 111: @@
 if a greater than 0 colon
-	print in double quotes positive
+	print within double quotes positive
 elif a less than 0 colon
   print in double quotes negative
 	else colon
-	    print in double quotes zero
+	    print within double quotes zero
 |-
@@ Line 327: / Line 327: @@
 |-
 | 10:23
-| Given a variable  time , print  Good Morning  if it is less than 12, otherwise print  Hello .
+| Given a variable  time , print  Good Morning  if it is less than 12, otherwise   Hello .
 |-
@@ Line 343: / Line 343: @@
 |-
 | 10:48
-| And now look at the answers,
+| And now lets  look at the answers,
 |-

@@ Line 28: / Line 28: @@
 |-
 | 0:45
-| For example, say, we have a variable <tt>a</tt> which stores integers and we are required to find out whether <tt>a</tt> is even or odd.
+| For example, say, we have a variable a which stores integers and we are required to find out whether a is even or odd.
 |-
 | 0:52
-| Let's say the value of <tt>a</tt> is 5.
+| Let's say the value of a is 5.
 |-
@@ Line 52: / Line 52: @@
 |-
 | 1:37
-| If <tt>a</tt> is divisible by 2, i.e., the result of "a modulo 2" is 0, it prints "Even", otherwise it prints "Odd".
+| If a is divisible by 2, i.e., the result of "a modulo 2" is 0, it prints "Even", otherwise it prints "Odd".
 |-
 |1:51
-| Note that in such a case, only one of the two blocks gets executed depending on whether the condition is <tt>True</tt> or <tt>False</tt>.
+| Note that in such a case, only one of the two blocks gets executed depending on whether the condition is  True  or <tt> False.
 |-
@@ Line 64: / Line 64: @@
 |-
 |2:03
-| Every code block begins with a line that ends with a <tt> colon</tt>, in this example the <tt>if</tt> and the <tt>else</tt> lines.
+| Every code block begins with a line that ends with a  colon, in this example the if  and the  else  lines.
 |-
@@ Line 92: / Line 92: @@
 |-
 | 2:49
-| We have a variable <tt>a</tt> which holds integer values.
+| We have a variable  a  which holds integer values.
 |-
 |2:52
-| We need to print "positive" if <tt>a</tt> is positive, "negative" if it is negative or "zero" if it is 0.
+| We need to print "positive" if  a  is positive, "negative" if it is negative or "zero" if it is 0.
 |-
@@ Line 123: / Line 123: @@
 |-
 | 4:24
-| The only addition here is the <tt>elif</tt> statement which can have another condition of its own.
+| The only addition here is the  elif  statement which can have another condition of its own.
 |-
 | 4:30
-| Here too, exactly one block of code is executed -- the block of code which first evaluates to <tt>True</tt>.
+| Here too, exactly one block of code is executed -- the block of code which first evaluates to  True .
 |-
@@ Line 139: / Line 139: @@
 |-
 | 4:59
-| Also, the <tt>else</tt> block in both if/else statement and if/elif/else is optional.
+| Also, the else  block in both if/else statement and if/elif/else is optional.
 |-
@@ Line 327: / Line 327: @@
 |-
 | 10:23
-| Given a variable <tt>time</tt>, print <tt>Good Morning</tt> if it is less than 12, otherwise print <tt>Hello</tt>.
+| Given a variable  time , print  Good Morning  if it is less than 12, otherwise print  Hello .
 |-
@@ Line 348: / Line 348: @@
 | 10:52
 | 1. We can use the if/else statements as
-  <nowiki>if time less than 12 colon</nowiki>
+   if time less than 12 colon
     print in double quotes Good Morning
    else colon