fmlexpr(1F)         (Form and Menu Language Interpreter)        fmlexpr(1F)

NAME
     fmlexpr - evaluate arguments as an expression

SYNOPSIS
     fmlexpr arguments

DESCRIPTION
     The fmlexpr function evaluates its arguments as an expression. After
     evaluation, the result is written on the standard output. Terms of the
     expression must be separated by blanks. Characters special to FMLI
     must be escaped. A 0 is returned to indicate a zero value rather than
     the null string. Strings containing blanks or other special characters
     should be quoted. Integer-valued arguments may be preceded by a unary
     minus sign. Internally, integers are treated as 32-bit, 2s complement
     numbers.

     The operators and keywords are listed below. Characters that need to
     be escaped are preceded by \. The list is in order of increasing pre-
     cedence with equal precedence operators grouped within {} symbols.

     expr \| expr
          Returns the first expr if it is neither null nor 0; otherwise
          returns the second expr.

     expr \& expr
          Returns the first expr if neither expr is null or 0; otherwise
          returns 0.

     expr { =, \>, \>=, \<, \<=, != } expr
          Returns the result of an integer comparison if both arguments are
          integers; otherwise returns the result of a lexical comparison.

     expr { +, - } expr
          Addition or subtraction of integer-valued arguments.

     expr { *, /, % } expr
          Multiplication, division, or remainder of the integer-valued
          arguments.

     expr : expr
          The matching operator : compares the first argument with the
          second argument which must be a regular expression. Regular
          expression syntax is the same as that of ed(1), except that all
          patterns are "anchored" (for example, begin with ^) therefore, ^
          is not a special character in this context. Normally the matching
          operator returns the number of bytes matched (0 on failure). The
          \(...\) pattern symbols can be used to return a portion of the
          first argument.







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fmlexpr(1F)         (Form and Menu Language Interpreter)        fmlexpr(1F)

EXAMPLES
     1.  Add 1 to the variable a:

              `fmlexpr $a + 1 | set -l a`

     2.  For $a equal to either /usr/abc/file or just file:

              fmlexpr  $a  :  '.*/\(.*\)'  \|  $a

         The example returns the last segment of a path name (for example,
         file). Watch out for / alone as an argument: fmlexpr will take it
         as the division operator.

     3.  A better representation of example 2.

              fmlexpr  //$a  :  '.*/\(.*\)'

         The addition of the // characters eliminates any ambiguity about
         the division operator because it makes it impossible for the
         left-hand expression to be interpreted as the division operator.
         It simplifies the whole expression.

     4.  Return the number of characters in $VAR.

              fmlexpr $VAR : .*

DIAGNOSTICS
     As a side effect of expression evaluation, fmlexpr returns the follow-
     ing exit values:

     0    If the expression is neither null nor 0 (for example, TRUE)

     1    If the expression is null or 0 (for example, FALSE)

     2    For invalid expressions (for example, FALSE).

     syntax error              For operator/operand errors.

     non-numeric argument      If arithmetic is attempted on such a string.

     An error message is printed at the current cursor position for syntax
     errors and non-numeric arguments. Use refresh to redraw the screen.












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fmlexpr(1F)         (Form and Menu Language Interpreter)        fmlexpr(1F)

NOTES
     After argument processing by FMLI, fmlexpr cannot tell the difference
     between an operator and an operand except by the value. If $a is an =,
     the command:

          fmlexpr  $a  =  '='

     looks like this:

          fmlexpr  =  =  =

     The arguments are passed to fmlexpr and they will all be taken as the
     = operator. The following works, and returns TRUE:

          fmlexpr  X$a  =  X=

SEE ALSO
     ed(1), expr(1), sh(1), set(1F).




































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