Python: Why does ("hello" is "hello") evaluate as True?

python identity string-comparison object-comparison
Deniz Dogan picture Deniz Dogan · Sep 8, 2009 · Viewed 19.3k times · Source

Why does "hello" is "hello" produce True in Python?

I read the following here:

If two string literals are equal, they have been put to same memory location. A string is an immutable entity. No harm can be done.

So there is one and only one place in memory for every Python string? Sounds pretty strange. What's going on here?

Answer

carl picture carl · Sep 8, 2009

Python (like Java, C, C++, .NET) uses string pooling / interning. The interpreter realises that "hello" is the same as "hello", so it optimizes and uses the same location in memory.

Another goodie: "hell" + "o" is "hello" ==> True

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