how to get a list with the value of the positions that contain a value.

[Adolfo_Enrique_]

Hello everyone, I need help to solve the following.

From a list with n data, how to get a list with the value of the positions that contain a value.

For example, from the following List( Pear,banana,Apple), the result I need to obtain is LIST(1,2,3)

Gracias!