XII Computer Science- Chapter 1-Function
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This document discusses computer science functions and their key concepts: - Functions are subroutines or blocks of code that perform a specific task and can be reused. They take parameters as inputs and return an output. - The interface of a function defines what it can do from the outside, while the implementation contains the internal code that carries out its behavior. - Pure functions always return the same output for given inputs, while impure functions may produce side effects or different outputs for the same inputs. - Examples demonstrate defining functions with and without parameters, recursive functions, and using functions to solve problems like determining if a number is even or odd.
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XII Computer Science- Chapter 1-Function
- 1. XII- COMPUTER SCIENCE CHAPTER 1 FUNCTION
- 2. INTRODUCTION The most important criteria in writing and evaluating the algorithm is the time it takes to complete a task. To have a meaningful comparison of algorithms, the duration of computation time must be independent of the programming language, compiler, and computer used. If a bulk of statements to be repeated for many numbers of times then subroutines are used to finish the task.
- 3. SUBROUTINES Subroutines are the basic building blocks of computer programs. Subroutines are small sections of code that are used to perform a particular task that can be used repeatedly. In Programming languages these subroutines are called as Functions.
- 4. Function A function is a unit of code that is often defined within a greater code structure. A function contains a set of code that works on many kinds of inputs, like variants, expressions and produces a concrete output.
- 5. Function Specification Let us consider the example a:= (24). a:= (24) has an expression in it but (24) is not itself an expression. Definitions bind values to names, in this case the value 24 being bound to the name a. Definitions are not expressions, at the same time expressions are also not treated as definitions. Definitions are distinct syntactic blocks.
- 6. Parameters (and arguments) Parameters are the variables in a function definition and arguments are the values which are passed to a function definition. 1. Parameter without Type 2. Parameter with Type
- 8. Parameter with Type With Data type Keyword Recursive Function name
- 9. Syntax for function definitions let rec fn a1 a2 ... an := k fn function name. The names a1 to an are variables indicating the identifiers used as parameters. The keyword rec is required if fn is to be a recursive function; A function definition which call itself is called recursive function.
- 10. Example to check whether the entered number is even or odd All functions are static definitions. There is no dynamic function definitions.
- 11. Interface Vs Implementation An interface is a set of action that an object can do. For example when you press a light switch, the light goes on, you may not have cared how it splashed the light. an Interface is a description of all functions that a class
- 12. Key points A class declaration combines the external interface (its local state) with an implementation of that interface (the code that carries out the behaviour). An object is an instance created from the class. The interface defines an objects visibility to the outside world.
- 14. Characteristics of interface The class template specifies the interfaces to enable an object to be created and operated properly. An object's attributes and behaviour is controlled by sending functions to the object.
- 15. Example
- 16. Pure functions Pure functions are functions which will give exact result when the same arguments are passed. For example the mathematical function sin (0) always results 0.
- 17. Pure functions strlen (s) is called each time and strlen needs to iterate over the whole of s. Evaluation of pure functions does not cause any side effects to its output
- 18. Impure functions The variables used inside the function may cause side effects though the functions which are not passed with any arguments. In such cases the function is called impure function. For example the mathematical function random() will give different outputs for the same function call.
- 20. Chameleons of Chromeland problem using function monochromatize (a, b, c) 6