Python Break Statement

The break statement is one that breaks out of a loop whenever there is a call for it. Like in the case when a certain condition is fulfilled, and you need to break out of the set loop. It can be used by both for and while loops.

Key Points:

1. Immediate Exit:

• When a break is encountered, the loop will stop immediately and program control moves to the first statement after the loop.

2. Use in Loops:

• Used in both for and while loops
• Commonly utilized with if statements which break out of the loop, indicating when to do it.

3. Nested Loops:

• In nested loops, the break statement only terminates the innermost loop in which it is used.

4. Skipping Else Clause:

• If the loop has an else block, then the else block is not executed if the loop is terminated using break.

Syntax:

for variable in sequence:
   if condition:
       break  # Exit the loop
   # Other loop logic

while condition:
   if condition:
       break  # Exit the loop
   # Other loop logic

Example 1: Breaking a while Loop

i = 0
while i < 10:
   print(i)
   if i == 5:  # Exit the loop when i equals 5
      break
   i += 1
print("Loop ended.")

Output:

0
1
2
3
4
5
Loop ended.

Example 2: Breaking a for Loop

for num in range(1, 11):
   print(num)
   if num == 7:  # Exit the loop when num equals 7
     break
print("Loop terminated.")

Output:

1
2
3
4
5
6
7
Loop terminated.

Example 3: Nested Loops with break

for i in range(3): # Outer loop
  for j in range(5): # Inner loop
      print(f"i={i}, j={j}")
      if j == 2: # Break the inner loop
         break

Output:

i=0, j=0
i=0, j=1
i=0, j=2
i=1, j=0
i=1, j=1
i=1, j=2
i=2, j=0
i=2, j=1
i=2, j=2

Example 4: Effect on Else Block

for num in range(5):
   if num == 3:
      break # Break the loop when num is 3
   print(num)
else:
   print("Loop completed successfully.") # This will not be executed

print("End of program.")

Output:

0
1
2
End of program.

Use Cases:

1. Stopping Early:

• When you find the desired value in a collection and do not need to continue searching.

2. Error Handling:

• Exit the loop in case of invalid input or an unexpected condition.

3. Efficiency:

• Reduce unnecessary computations by exiting loops early when a result is found.