Unevaluated

Unevaluated[expr]
represents the unevaluated form of expr when it appears as the argument to a function.

effectively works by temporarily setting attributes so that f holds its argument unevaluated, then evaluating .

Feed an unevaluated expression to Length:

Out[1]=

Use HoldAll and Unevaluated to suppress evaluation of symbols wherever it would occur:

Find the length of a symbol's name even if it has a value:

Unevaluated works only where it appears; it is not propagated:

Unevaluated inside a held function remains:

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