In this post, we will have a look on various type of looping constructs in Ruby.
*Note: First of all keep in mind that Python is very strict on tab keys. Each tab key represents child statement.
Loops are program constructs that are used to repeat statements inside its body until some condition is satisfied.
Following are the type of loops we can use in Python:
1. While Loop
While loop executes its statements till the condition is true. The syntax of while loop is:
i = 1 n = 5 while i <= 10: print("%d * %d = %d" % (i, n, i*n)) i +=1
2. Single line While Loop
We can write the while loop on single line as well.
i = 1 n = 5 while i <= 10: print("%d * %d = %d" % (i, n, i*n)); i+=1
3. For Loop
For loops are used to iterate over a predefined set of data. For example, iterate over an array or iterate over a given range.
a. Counter based for loop
This loop executes its statements by updating a loop counter. When loop counter reaches the maximum specified value, the loop execution stops. Here is the syntax:
for counter in range(start, end+1) end
Let us say, we have to run the loop from 1 to 10, the range for this will have start=1 and end=10+1. The loop counts up to one less than end value.
Let us check an example that calculates the sum of first 10 numbers.
sum = 0 for counter in range(1,11): sum = sum + counter print("Sum %d" % sum)
By default, the loop counter increments by 1. If you want to increment loop counter by some other value, you can do:
for counter in range(1,11,2): print(counter);
b. For loop iterating over array
This type of for loop is used to iterate over a collection like array. The syntax is:
for variable in collection:
languages = ["Python", "PHP", "Java", "C#"] for x in languages: print(x)
Breaking the loop
We can stop the execution of a loop in the middle with the help of break statement. Here is an example:
n = 1 while n%10 != 0: print("n = %d" % n) n +=1 if n>5: break
Skipping loop statements
We can skip rest of the loop and jump to next iteration with the help of continue. Here is an example that prints odd numbers from 1 to 10:
n = 1 while n<10: n +=1 if n%2 == 0: continue print("n = %d" % n)