Python for loop
The "for" is an iteration loop in Python like other programming languages. The for loop is generally programmer's first choice when they want to iterate in their code, especially when the limit of the iteration is known and predefined. We can iterate elements in collection or sequence(iterable objects) in Python using for loop. For example, we can iterate over a list, tuple, set, or dictionary.
Iterating a List,
Iterating in a range,
We can iterate over a provided range.Iterating a List,
for item in [14,17,20,11,25]: print(item) Output: 14 17 20 11 25
Iterating in a range,
for item in range(1,5): print(item) Output: 1 2 3 4
or,
If we want to iterate a list with an index of the item then we can use enumerate function. For example
for item in range(4): print(item) Output: 0 1 2 3
for loop is iterated over any iterable object, which is an object defines a __getitem__ or a __iter__ function. The __ iter__ method returns an iterator, which is an object with a next function that is used to access the next element of the given iterable.
for item in ["Python","is","easy","yet","powerful","programming","language"]: print(item) Output: Python is easy yet powerful programming language
If we want to iterate a list with an index of the item then we can use enumerate function. For example
for index, element in enumerate(["Python","is","easy","yet","powerful","programming","language"]): print(index,"->",element) Output: 0 -> Python 1 -> is 2 -> easy 3 -> yet 4 -> powerful 5 -> programming 6 -> language
The 'break' statement in a loop
The "break" statement forces control to come out the innermost loop, in an iteration.break are generally applied inside if statement nested inside an iteration statement like for, while and do-while.
def linearSearch(num): count=0 l=[7,12,25,0,11,36,41] length=len(l) for x in l: count=count+1 if num==x: print('found') break #control will come out from the loop if count>=length: print('not found') linearSearch(11) linearSearch(75) Output: found not found
The 'continue' statement in a loop
The "continue" statement will jump to the next iteration, skipping all remaining code inside the current loop block but continuing the loop. Like break, continue can appear inside loops only.
for x in range(1,20): if x%2==0 or x%3==0: continue print('2 and 3 are not a divisor of ',x) Output: 2 and 3 are not a divisor of 1 2 and 3 are not a divisor of 5 2 and 3 are not a divisor of 7 2 and 3 are not a divisor of 11 2 and 3 are not a divisor of 13 2 and 3 are not a divisor of 17 2 and 3 are not a divisor of 19
The 'else' clause with for-loop
The "for-loop" optionally can have else clause, for examplefor i in range(3): print(i) else: print('range finished') Output: 0 1 2 range finished
Iterating String with for loop
Strings are iterable objects and can be iterated over for loop easily.for i in 'Python': print(i) Output: P y t h o n