if you_smart: print "learn python" else: print "go away"
In general, statements are executed sequentially: The first statement in a function is executed first, followed by the second, and so on. There may be a situation when you need to execute a block of code several number of times.
Programming languages provide various control structures that allow for more complicated execution paths. A loop statement allows us to execute a statement or group of statements multiple times. The following diagram illustrates a loop statement
Python programming language provides following types of loops to handle looping requirements.
|while loop||Repeats a statement or group of statements while a given condition is TRUE. It tests the condition before executing the loop body.|
|for loop||Executes a sequence of statements multiple times and abbreviates the code that manages the loop variable.|
|nested loops||You can use one or more loop inside any another while, for or do..while loop.|
A while loop statement in Python programming language repeatedly executes a target statement as long as a given condition is true.
The syntax of a while loop in Python programming language is
while expression: statement(s)
count = 0 while count < 9: print 'The count is:', count count += 1 print "Good bye!"
It has the ability to iterate over the items of any sequence, such as a list or a string.
for iterating_var in sequence: statements(s)
If a sequence contains an expression list, it is evaluated first. Then, the first item in the sequence is assigned to the iterating variable iterating_var. Next, the statements block is executed. Each item in the list is assigned to iterating_var, and the statement(s) block is executed until the entire sequence is exhausted.
for i in range(10): print "hello", i for letter in 'Python': print 'Current letter :', letter fruits = ['banana', 'apple', 'mango'] for fruit in fruits: print 'Current fruit :', fruit print "Good bye!"
Yield and Generator
Yield is a keyword that is used like return, except the function will return a generator.
def createGenerator(): yield 1 yield 2 yield 3 mygenerator = createGenerator() # create a generator print(mygenerator) # mygenerator is an object! # <generator object createGenerator at 0xb7555c34> for i in mygenerator: print(i) # 1 # 2 # 3
Visit Yield and Generator explained for more information
- "Python Loops". www.tutorialspoint.com
- "What does the “yield” keyword do?". stackoverflow.com
- "Improve Your Python: 'yield' and Generators Explained". jeffknupp.com
def functionname([formal_args,] *var_args_tuple ): "function_docstring" function_suite return [expression]
#!/usr/bin/python # Function definition is here def printinfo( arg1, *vartuple ): "This prints a variable passed arguments" print "Output is: " print arg1 for var in vartuple: print var return; # Now you can call printinfo function printinfo( 10 ) printinfo( 70, 60, 50 )
Indentation: 4 spaces