Computer Science Class 11 English

  CBSE Revision Notes Class-11 Informatics Practices  (New Syllabus) Unit 1: Programming and Computational Thinking History of Computers One of the earliest machines designed to assist people in calculations was the  abacus  which is still being used some 5000 years after its invention. In 1642 Blaise Pascal (a famous French mathematician) invented an adding machine based on mechanical gears in which numbers were represented by the cogs on the wheels. Englishman, Charles Babbage, invented in the 1830's a "Difference Engine" made out of brass and pewter rods and gears, and also designed a further device which he called an "Analytical Engine". His design contained the five key characteristics of modern computers:- An input device Storage for numbers waiting to be processed A processor or number calculator A unit to control the task and the sequence of its calculations An output device Augusta Ada Byron (later Countess of Lovelace) was an associate of Babbage who h...

  CBSE Revision Notes Class-11 Informatics Practices (New Syllabus) Unit 1: Programming and Computational Thinking (PCT-1) This topic is common in class 11 computer science and informatics practices. Basic Python Programming and Simple Data Types Familiarization with the basics of Python programming Guido van Rossum created the Python programming language in the late 1980s. In contrast to other popular languages such as C, C++, Java, and C#, Python strives to provide a simple but powerful syntax. Python is used for software development at companies and organizations such as Google, Yahoo and NASA. Simple Hello program:  Python programs must be written with a particular structure. The syntax must be correct, or the interpreter will generate error messages and not execute the program. When we want to write a program, we use a text editor to write the Python instructions into a file, which is called a script. By convention, Python scripts have names that end with .py. For example...

  CBSE Revision Notes Class-11 Informatics Practices (New Syllabus) Unit 1: Programming and Computational Thinking (PCT-1) This topic is common in class 11 Computer Science and Informatics Practices. Variables and Manipulating Methods Variable  is a name assigned to a memory location to store the data. The data that a variable can store depends on data type for example X=20 y=20.5 z=”Hello” Here x, y and z are name of three variables all of them are holding different data depending on their data type e.g x is holding integer type data y is holding float type and z is holding string data. Basically all this data is stored in memory and it’s accessed by its name called variables. Variables are nothing but name given to a memory location or we can say it is a reference to a memory location where the data is stored we can easily access the data from memory using these variables. Variables need not be declared first in python. They can be used directly. Variables in python are case...

  CBSE Revision Notes Class-11 Informatics Practices (New Syllabus) Unit 1: Programming and Computational Thinking (PCT-1) This topic is common in class 11 Computer Science and Informatics Practices. Data Types and Operators Knowledge of data types and operators: We have already seen different data types in python. Now we will see what are different operators in python and how we can take input from the keyboard. Accepting input from console:  There are two ways to assign value to a variable 1. By assigning value during compile time e.g. x=10, y=99.22, z=”hello”. 2.  We can also assign value at run time e.g. we’ll ask user to insert the value during run time. This is the mostly used in programming. We assign value at compile time when the value won’t change in the program. Let’s see an example how we can take input from the keyboard. For this we use the function called input(). This function takes input from keyboard and assigns the value to the variable. Print(‘enter any...

  CBSE Revision Notes Class-11 Informatics Practices (New Syllabus) Unit 1: Programming and Computational Thinking (PCT-1) This topic is common in class 11 Computer Science and Informatics Practices. Conditional Statements and Simple Programs Conditional statements In conditional statement we check for specific conditions. its value can be either true or false. If it’s true some statements are executed else some other statements will be executed. Conditions can be checked using some operators like < (less than), <=(less than equal to), >(greater than), >=(greater than equal to), ==(equal to), !=(not equal to). Let’s see how to use these operators in the expression and what will be the output of each expression. 20<40 true 40>80 False x<=10 True if value of x is less than or equal to 10 else false x!=y True if x is not equal to y else false x==y True if value of x and y is same else false 20<=20 True Let’s see with the help of flowchart how it actually works....

  CBSE Revision Notes Class-11   Informatics Practices  (New Syllabus) Unit 1: Programming and Computational Thinking (PCT-1) Iterative computation and control flow Notion of iterative computation and control flow:  Iteration repeats the execution of a sequence of code. Iteration is useful for solving many programming problems. Iteration and conditional execution form the basis for algorithm construction. while Loop:  Repeats a statement or group of statements while a given condition is TRUE. It tests the condition before executing the loop body. Let’s try to understand why we need iterative statements or loops. Have a look at these 5 statements. Print(1) Print(2) Print(3) Print(4) Print(5) If we have to print 5 numbers we need to write 5 different statement but with the help of loops we can achieve it using 1 print statement have a look at this example count=1 #counter initialized to 1 while count<=5: #this statement will repeat until condition is true print...