root [0] .x staff.C
******************************************************************************
*Tree    :T         : staff data from ascii file                             *
*Entries :     3354 : Total =          172042 bytes  File  Size =      47309 *
*        :          : Tree compression factor =   2.90                       *
******************************************************************************
*Br    0 :staff     : Category/I:Flag:Age:Service:Children:Grade:Step:Hrweek:*
*         | Cost                                                             *
*Entries :     3354 : Total  Size=     122235 bytes  File Size  =      32316 *
*Baskets :        3 : Basket Size=      32000 bytes  Compression=   2.97     *
*............................................................................*
*Br    1 :Division  : Division/C                                             *
*Entries :     3354 : Total  Size=      25307 bytes  File Size  =       8319 *
*Baskets :        1 : Basket Size=      32000 bytes  Compression=   2.49     *
*............................................................................*
*Br    2 :Nation    : Nation/C                                               *
*Entries :     3354 : Total  Size=      24190 bytes  File Size  =       6674 *
*Baskets :        1 : Basket Size=      32000 bytes  Compression=   3.06     *
*............................................................................*

root [1] TFile f("staff.root")

root [2] f->ls()                   // you can see what is written in the file
TFile**         staff.root
 TFile*         staff.root
  KEY: TTree    T;1     staff data from ascii file

root [3] T->Show(10)
======> EVENT:10
 Category        = 361
 Flag            = 15
 Age             = 51
 Service         = 29
 Children        = 0
 Grade           = 7
 Step            = 13
 Hrweek          = 40
 Cost            = 7599
 Division        = PS
 Nation          = FR

root [4] T->Print()
******************************************************************************
*Tree    :T         : staff data from ascii file                             *
*Entries :     3354 : Total =          245417 bytes  File  Size =      59945 *
*        :          : Tree compression factor =   2.90                       *
******************************************************************************
*Br    0 :staff     : Category/I:Flag:Age:Service:Children:Grade:Step:Hrweek:*
*         | Cost                                                             *
*Entries :     3354 : Total  Size=     154273 bytes  File Size  =      32316 *
*Baskets :        3 : Basket Size=      32000 bytes  Compression=   2.97     *
*............................................................................*
*Br    1 :Division  : Division/C                                             *
*Entries :     3354 : Total  Size=      46114 bytes  File Size  =       8319 *
*Baskets :        1 : Basket Size=      32000 bytes  Compression=   2.49     *
*............................................................................*
*Br    2 :Nation    : Nation/C                                               *
*Entries :     3354 : Total  Size=      44659 bytes  File Size  =       6674 *
*Baskets :        1 : Basket Size=      32000 bytes  Compression=   3.06     *
*............................................................................*

root [5] T->Scan("Cost:Age:Children")
************************************************
*    Row   *      Cost *       Age *  Children *
************************************************
*        0 *     11975 *        58 *         0 *
*        1 *     10228 *        63 *         0 *
*        2 *     10730 *        56 *         2 *
*        3 *      9311 *        61 *         0 *
*        4 *      9966 *        52 *         2 *
*        5 *      7599 *        60 *         0 *
*        6 *      9868 *        53 *         1 *
*        7 *      8012 *        60 *         1 *
*        8 *      8813 *        51 *         0 *
*        9 *      7850 *        56 *         1 *
*       10 *      7599 *        51 *         0 *
*       11 *      9315 *        54 *         2 *
*       12 *      7599 *        54 *         0 *
*       13 *      7892 *        46 *         0 *
*       14 *      7850 *        54 *         1 *
*       15 *      7599 *        57 *         0 *
*       16 *      8137 *        55 *         0 *
*       17 *      7850 *        55 *         1 *
*       18 *      7294 *        57 *         1 *
*       19 *      8101 *        51 *         2 *
*       20 *      5720 *        54 *         0 *
*       21 *     15832 *        57 *         1 *
*       22 *     12226 *        63 *         1 *
*       23 *     13135 *        56 *         0 *
*       24 *      9617 *        49 *         0 *
Type <CR> to continue or q to quit ==> etc...