This is documentation for Mathematica 8, which was
based on an earlier version of the Wolfram Language.
View current documentation (Version 11.2)

First

First[expr]
gives the first element in expr.
  • First[expr] is equivalent to .
Extract the first element of a list:
Extract the first row of a matrix:
The head need not be List:
Extract the first element of a list:
In[1]:=
Click for copyable input
Out[1]=
 
Extract the first row of a matrix:
In[1]:=
Click for copyable input
Out[1]=
 
The head need not be List:
In[1]:=
Click for copyable input
Out[1]=
First[expr] is equivalent to :
The expression is evaluated before First is applied:
First always operates on the FullForm of expressions:
New in 1