• ← PutAppend
• → ReadList

Read

WMA link

Read[stream]

reads the input stream and returns one expression.

Read[stream, type]

reads the input stream and returns an object of the given type.

Read[stream, type]

reads the input stream and returns an object of the given type.

Read[stream, Hold[Expression]]

reads the input stream for an Expression and puts it inside Hold.

type is one of:

• Byte
  
• Character
  
• Expression
  
• HoldExpression
  
• Number
  
• Real
  
• Record
  
• String
  
• Word
  

• • stream = StringToStream["abc123"];

• • Read[stream, String]

• • Read[stream, String]

• • stream = StringToStream["abc 123"];

• • Read[stream, Word]

• • Read[stream, Word]

• • Read[stream, Word]

• • stream = StringToStream["123, 4"];

• • Read[stream, Number]

• • Read[stream, Number]

• • Read[stream, Number]

• • stream = StringToStream["2+2\n2+3"];

Read with a Hold[Expression] returns the expression it reads unevaluated so it can be later inspected and evaluated:

• • Read[stream, Hold[Expression]]

• • Read[stream, Expression]

Reading a comment, a non-expression, will return Hold[Null]

• • stream = StringToStream["(* ::Package:: *)"];

• • Read[stream, Hold[Expression]]

• • stream = StringToStream["123 abc"];

• • Read[stream, {Number, Word}]

• • Read[stream, {Number, Word}]

Multiple lines:

• • stream = StringToStream["\"Tengo una\nvaca lechera.\""]; Read[stream]