input line. 
In
In[n]
is a global object that is assigned to have a delayed value of the n
input line.
input line to be reevaluated. Examples
open all close allBasic Examples (1)
Scope (1)
Applications (1)
a = 1.;b = 3 / 2;a = a / 2 + b / aReevaluate the third input 4 more times:
Table[In[3], {4}]
a - Sqrt[3]Evaluate DownValues for In to see what inputs are stored in this session:
DownValues[In]Get the same data using Information. Here this only includes definitions from this example:
??InProperties & Relations (4)
Referencing an input number greater than the total number of inputs returns unevaluated:
In[5]If $HistoryLength is finite, only the $HistoryLength-1 most recent values of In have a value:
$HistoryLength = 3;
1 + 1
2 + 2
3 + 3
Table[In[n], {n, 4}]
$HistoryLength=.The value of $Line corresponds to the numbers in In and Out:
1 + 1$LineIn[] and In[-1] are equivalent:
Echo[5]In[] === In[-1]Related Links
Fast Introduction for Programmers: Interactive UsageText
Wolfram Research (1988), In, Wolfram Language function, https://reference.wolfram.com/language/ref/In.html.
CMS
Wolfram Language. 1988. "In." Wolfram Language & System Documentation Center. Wolfram Research. https://reference.wolfram.com/language/ref/In.html.
APA
Wolfram Language. (1988). In. Wolfram Language & System Documentation Center. Retrieved from https://reference.wolfram.com/language/ref/In.html