EXERCISE - 1 BASICS
A) Running instructions in Interactive interpreter and a Python Script
B) Write a program to purposefully raise Indentation Error and Correct it
1 A) AIM: Running instructions in Interactive interpreter and
a Python Script
INTRODUCTIONS TO PYTHON
Python is a high-level programming language designed to be
easy to read and simple to implement. It is open source, which means it is free to use, even for commercial
applications. Python can run on Mac, Windows, and UNIX systems and has also
been ported to Java and .NET virtual machines.
Scripts written in Python (.PY files) can be parsed and run
immediately. They can also be saved as a compiled programs (.PYC files), which are often used as programming modules
that can be referenced by other Python programs.
Python Interactive Mode:
Python has two basic
modes: normal and interactive. The normal mode is the mode where the scripted
and finished
.py files are run
in the Python interpreter. Interactive mode is a command line shell which gives
immediate feedback for each statement, while running previously fed statements
in active memory. As new lines are fed into the interpreter, the fed program is
evaluated both in part and in whole.
Interactive mode is a
good way to play around and try variations on syntax.
On Windows, bring up
the command prompt and type "python", or start an interactive Python
session by selecting "Python (command line)", "IDLE", or
similar program from the task bar / app menu. IDLE is a GUI which includes both
an interactive mode and options to edit
and run files.
When commands are read from a tty, the interpreter is said to be
in interactive mode. In this mode it prompts for the next command
with the primary prompt, usually three greater-than signs (>>>);
for continuation lines it prompts with the secondary prompt, by
default three dots (...). The interpreter prints a welcome message stating its version number
and a copyright notice before printing the first prompt:
Python
3.6.1 (v3.6.1:69c0db5, Mar 21 2017, 17:54:52) [MSC v.1900 32 bit (Intel)] on
win32
Type
"copyright", "credits" or "license()" for more
information.
>>>
Once the Python
interpreter is started, you can issue any command at the command prompt
">>>".
The first real command we will use is the print command. We will create the mandatory “Hello World” statement:
>>> l = [“A”,42,78,”Just a String”]
>>>for character in l:
... print(character)
...
A
42
78
Just a String
>>>
The problem is that Python requires formatting of blocks like this with indentation. So to correct that error in the above code, I would simply do:
The first real command we will use is the print command. We will create the mandatory “Hello World” statement:
>>> l = [“A”,42,78,”Just a String”]
>>>for character in l:
... print(character)
...
A
42
78
Just a String
>>>
The problem is that Python requires formatting of blocks like this with indentation. So to correct that error in the above code, I would simply do:
>>>print(“Hello World”)
Hello World
>>>
We
will show how the interactive prompt deals with multiline statements like for
loops.
2 B) AIM:Write a program to purposefully raise Indentation Error and Correct it.
INTRODUCTION TO INDENTATION:
Python does not use braces({}) to indicate blocks of code for class and function definitions or flow control. Blocks of code are denoted by line indentation, which is rigidly enforced.
The number of spaces in the indentation is variable, but all statements within the block must be indented the same amount. For example,
if True:
print(“True”)
else:
print(“False”)
if
True:
print(“True”)
else:
print(“False”)