With the while loop we can execute a set of statements as long as a condition is true.
Syntax:
while condition:
<indented statement 1>
<indented statement 2>
...
<indented statement n>
<non-indented statement 1>
<non-indented statement 2>
Some Important Points:
First the condition is evaluated. If the condition is true then statements in the while block is executed.
After executing statements in the while block the condition is checked again and if it is still true, then the statements inside the while block is executed again.
The statements inside the while block will keep executing until the condition is true.
Each execution of the loop body is known as iteration.
When the condition becomes false loop terminates and program control comes out of the while loop to begin the execution of statement following it.
Example:
i=1
while i<=10:
print(i)
i=i+1
print("done!")
Output:
1
2
3
4
5
6
7
8
9
10
done!
Example:
i=1
while i<=10:
print(i)
i=i+1
print("done!")
Output:
1
1
1
1
1
1
1
1
.
.
.
In Python , just like we have an else with if , similarly we also can have an else part with the while loop.
The statements in the else part are executed, when the condition is not fulfilled anymore.
while condition:
<indented statement 1>
<indented statement 2>
...
<indented statement n>
else:
<indented statement 1>
<indented statement 2>
Some Important Points:
Many programmer’s have a doubt that If the statements of the additional else part were placed right after the while loop without an else, they would have been executed anyway, wouldn't they.
Then what is the use of else
To understand this , we need to understand the break statement. Our next tutorial is on Break and Continue statement and will help you understand this concept.