if(n)                 Tcl Built-In Commands                 if(n)



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NAME
     if - Execute scripts conditionally

SYNOPSIS
     if _e_x_p_r_1 ?then? _b_o_d_y_1 elseif _e_x_p_r_2 ?then? _b_o_d_y_2  elseif  ...
     ?else? ?_b_o_d_y_N?
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DESCRIPTION
     The _i_f command evaluates _e_x_p_r_1 as an expression (in the same
     way  that  expr  evaluates  its argument).  The value of the
     expression must be a boolean (a numeric value,  where  0  is
     false  and  anything is true, or a string value such as true
     or yes for true and false or no for false); if  it  is  true
     then _b_o_d_y_1 is executed by passing it to the Tcl interpreter.
     Otherwise _e_x_p_r_2 is evaluated as an expression and if  it  is
     true  then  body2  is  executed,  and so on.  If none of the
     expressions evaluates to true then _b_o_d_y_N is  executed.   The
     then and else arguments are optional ``noise words'' to make
     the command easier to read.  There  may  be  any  number  of
     elseif  clauses,  including zero.  _B_o_d_y_N may also be omitted
     as long as else is omitted too.  The return value  from  the
     command  is the result of the body script that was executed,
     or an empty string if none of the expressions  was  non-zero
     and there was no _b_o_d_y_N.


KEYWORDS
     boolean, conditional, else, false, if, true























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