use of Functions to write python program.pptx

use of Functions to write python program.pptx

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  Functions in PYTHON Rahul SinghSikarwar
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  Functions • A functionis a device that groups a set of statements so they can be run more than once in a program—a packaged procedure invoked by name • Functions also can compute a result value and let us specify parameters that serve as function inputs and may differ each time the code is run. • More fundamentally, functions are the alternative to programming by cutting and pasting—rather than having multiple redundant copies of an operation’s code, we can factor it into a single function.
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  Function-related statements and expressions
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  Introduction • Functions area nearly universal program-structuring device. You may have come across them before in other languages, where they may have been called subroutines or procedures. • As a brief introduction, functions serve two primary development roles: 1. Maximizing code reuse and minimizing redundancy 2. Procedural decomposition
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  • def isexecutable code. Python functions are written with a new statement, the def.  def is an executable statement—your function does not exist until Python reaches and runs the def. In fact, it’s legal (and even occasionally useful) to nest def statements inside if statements, while loops, and even other defs. • def creates an object and assigns it to a name.: When Python reaches and runs a def statement, it generates a new function object and assigns it to the function’s name. As with all assignments, the function name becomes a reference to the function object • lambda creates an object but returns it as a result: Functions may also be created with the lambda expression, a feature that allows us to in-line function definitions in places where a def statement won’t work syntactically.
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  • return sendsa result object back to the caller: When a function is called, the caller stops until the function finishes its work and returns control to the caller. Functions that compute a value send it back to the caller with a return statement; the returned value becomes the result of the function call. A return without a value simply returns to the caller • yield sends a result object back to the caller, but remembers where it left off. Functions known as generators may also use the yield statement to send back a value and suspend their state such that they may be resumed later, to produce a series of results over time
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  def Statements • Thedef statement creates a function object and assigns it to a name. Its general format is as follows: def name(arg1, arg2,... argN): Statements Function bodies often contain a return statement: def name(arg1, arg2,... argN): ... return value The Python return statement can show up anywhere in a function body; when reached, it ends the function call and sends a result back to the caller. The return statement consists of an optional object value expression that gives the function’s result. If the value is omitted, return sends back a None.
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  nest a functiondef inside an if statement to select between alternative definitions: if test: def func(): # Define func this way ... else: def func(): # Or else this way ... ... func() # Call the version selected and built
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  A First Example:Definitions and Calls Definition: Here’s a definition typed interactively that defines a function called times, which returns the product of its two arguments: >>> def times(x, y): # Create and assign function ... return x * y # Body executed when called ... >>> times(2, 4) # Arguments in parentheses 8
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  Calls
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  Python program forsolving a quadratic equation of the form ax 2 +bx+c=0 1. Use function def() to find the solution 2. a ,b and c is user input. Input 1: a= 1, b=-3, c=2 Input 2: a= 1, b=-8, c=5 Input 3: a=5, b= 20, c= 32