Python - For Loop

To iterate repeatedly through a sequence, use a for loop (that is, a list, tuple, dictionary, set, or string).

This works more like an iterative method seen in other object-oriented programming languages and is less like the for keyword found in other programming languages.

The for loop allows us to execute a series of statements once for each item in a list, tuple, set, etc.

cars = ["Renault", "Peugeot", "BMW"]
for x in cars:
 print(x)

Browse a string

You can browse a string character by character:

for x in "Peugeot":
 print(x)

The break statement in a for

With the break statement you can stop the for.

cars = ["Renault", "Peugeot", "BMW"]
for x in cars:
      print(x)
      if x == "Peugeot":
 break

The statement continues in a for

With the continue instruction we can stop the current iteration and move on to the next element.

cars = ["Renault",  "Peugeot", "BMW"]
for x in voitures:
      print(x)
      if x == "Peugeot":
 continue

The range()

The range() function allows us to iterate through a set of code a predetermined number of times.

The range() function returns a series of numbers that, by default, starts at 0 and increments by 1 before stopping at a predetermined value.

for x in range(4, 8):
 print(x)

The initial value of the range() function is 0 by default, but a starting value can be specified by adding a parameter: range(4, 8), which indicates values from 4 to 6 (but excluding 8:

Else in a for

else loop is used to specify the block of statements that will be executed once the for loop is complete.

for x in range(8): 
 print(x)
else:
 print("the for loop is complete")

Note: The instruction block in else does not execute if you add a break in the for loop.

Nested for loop

A nested for loop is a loop inside another for loop. It's perfect for traversing a matrix for example:

rows=["1", "2", "3"]
columns = ["4", "5", "6"]

for x in rows:
 for y in columns: 
 print(x, y)