Are you searching a code in VBA or a function in Excel Worksheet?
If a code in VBA then in the Module copy this;

Sub CheckEntireRow()
Dim Counter as Integer
For Counter = 1 to 2^16
If Range("B" & Counter).Value2>100 then
Range("C" & Counter).Value2 = 1
Else
Range("C" & Counter).Value2 = 0
End If
End Sub