CODEWITHSUNDEEP
pythonfor-loopscopenestedcontinue
Michael Crowley
Michael Crowley

Reputation: 131

What Is The Scope Of Continue In A Nested Python For Loop?

When using nested for loops, if I use continue inside the inner nested for loop, does the scope of that continue only apply to the inner loop or will it continue the outer loop?

Note: For what I am working on I only want the continue to affect the nested loop

b = ["hello"] * 5
d = ["world"] * 10

for a in b: # Outer Loop
    x = 1 + 1
    for c in d: # Nested Loop
        if c:
            x += 1
        else: 
            continue # Does this affect the Nested Loop or the Outer Loop

Upvotes: 4

Views: 3210

Answers (3)

Dope
Dope

Reputation: 11

As @botiapa said : It only affects the inner loop.

Now, if you want to make a working process to affect upper scope loop you have 2 solutions:

1 - Use variables at the top of the upper scope loop:

b = ["hello"] * 5
d = ["world"] * 10

for a in b: # Outer Loop

    outer_loop_should_break = False
    
    x = 1 + 1
    for c in d: # Nested Loop
        if c:
            x += 1
        else:
            outer_loop_should_break = True
            break # Does this affect the Nested Loop
     
     if outer_loop_should_break:
         break
     else:
         # do something

2 - Use Exceptions to have better traces:

class ShouldBreak(Exception):
    pass

class ShouldContinue(Exception):
    pass

b = ["hello"] * 5
d = ["world"] * 10

for a in b: # Outer Loop
    x = 1 + 1
    try:
        for c in d: # Nested Loop
            if c:
                x += 1
            else:
                raise ShouldBreak("explain why")
                # Or
                raise ShouldContinue("explain why")

    except ShouldBreak as sb:
        print(str(sb))
        break
    except ShouldContinue as sc:
        print(str(sc))
        continue
     
     # do something else after

If you really want to use namespaces for loop, you can switch to JavaScript and use label on loops : Docs here

Upvotes: 0

Abion47
Abion47

Reputation: 24736

Loop control keywords like break and continue only affect the closest loop in scope to them. So if you have a loop nested in another loop, the keyword targets whatever loop it is immediately within, not loops farther up the line.

Upvotes: 3

botiapa
botiapa

Reputation: 403

It only affects the inner loop.

Upvotes: 11

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