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KeyError

KeyError(key)

An indexing operation into an Associative (Dict) or Set like object tried to access or delete a non-existent element.

Examples

In the Julia programming language, the function KeyError(key)

This function is typically used when an indexing operation into an Associative (Dict) or Set-like object attempts to access or delete a non-existent element.

julia> d = Dict("apple" => 1, "banana" => 2, "orange" => 3);

julia> d["grape"]
ERROR: KeyError: key "grape" not found

Common example of its use:

julia> d = Dict("apple" => 1, "banana" => 2, "orange" => 3);

julia> key = "mango";

julia> try
           d[key]
       catch err
           if isa(err, KeyError)
               println("KeyError occurred for key: $key")
           else
               rethrow(err)
           end
       end
KeyError occurred for key: mango

This example demonstrates the use of KeyError in handling an exception when accessing a non-existent key in a dictionary (Dict). It catches the KeyError and performs custom error handling.

It's important to note that KeyError can also be raised when attempting to delete a non-existent key from an Associative (Dict) or Set-like object.

See Also

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