Built-in Mathematica Symbol

Length

Length[expr]
gives the number of elements in expr.

When expr is a SparseArray object, Length[expr] returns the length of the corresponding ordinary list. »

Find the length of a list:

Length works with any head:

Length[expr] gives the number of elements in the top level of expr:

The length of a symbol is 0:

The length of a string is 0:

StringLength gives the number of characters:

Explicit numbers have length 0:

Length works on SparseArray objects:

Find the number of rows in a matrix:

Find the length of each sublist:

Find the number of terms in a polynomial:

Find the number of digits in 1000!:

Get the number of points used to plot a curve:

Length gives the maximum index that can be used:

Length operates on the FullForm of expressions, not their displayed form:

Rational and complex numbers are atoms, so have length 0:

Numeric expressions are treated like other expressions, not like explicit numbers:

Length counts only "arguments", not parts of heads:

For nonatomic e, Length[e] is equivalent to First[Dimensions[e]]: