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Tcl_ExprLong(3tcl) Tcl Library Procedures Tcl_ExprLong(3tcl)
 


NAME

Tcl_ExprLong, Tcl_ExprDouble, Tcl_ExprBoolean, Tcl_ExprString - evaluate an
  expression

SYNOPSIS


#include <tcl.h>


int
Tcl_ExprLong(interp, expr, longPtr)


int
Tcl_ExprDouble(interp, expr, doublePtr)


int
Tcl_ExprBoolean(interp, expr, booleanPtr)


int
Tcl_ExprString(interp, expr)



ARGUMENTS



  
Tcl_Interp *interp (in)

  
Interpreter in whose context to evaluate expr.





  
const char *expr (in)

  
Expression to be evaluated.





  
long *longPtr (out)

  
Pointer to location in which to store the integer value of the
    expression.





  
int *doublePtr (out)

  
Pointer to location in which to store the floating-point value of the
      expression.





  
int *booleanPtr (out)

  
Pointer to location in which to store the 0/1 boolean value of the
      expression.
    
    

    
 

    

  




DESCRIPTION

These four procedures all evaluate the expression given by the expr
  argument and return the result in one of four different forms. The expression
  can have any of the forms accepted by the expr command. Note that these
  procedures have been largely replaced by the object-based procedures
  Tcl_ExprLongObj, Tcl_ExprDoubleObj, Tcl_ExprBooleanObj,
  and Tcl_ExprObj. Those object-based procedures evaluate an expression
  held in a Tcl object instead of a string. The object argument can retain an
  internal representation that is more efficient to execute.


The interp argument refers to an interpreter used to evaluate the
  expression (e.g. for variables and nested Tcl commands) and to return error
  information.


For all of these procedures the return value is a standard Tcl result:
  TCL_OK means the expression was successfully evaluated, and
  TCL_ERROR means that an error occurred while evaluating the expression.
  If TCL_ERROR is returned then the interpreter's result will hold a
  message describing the error. If an error occurs while executing a Tcl command
  embedded in the expression then that error will be returned.


If the expression is successfully evaluated, then its value is returned in one
  of four forms, depending on which procedure is invoked. Tcl_ExprLong
  stores an integer value at *longPtr. If the expression's actual value
  is a floating-point number, then it is truncated to an integer. If the
  expression's actual value is a non-numeric string then an error is returned.


Tcl_ExprDouble stores a floating-point value at *doublePtr. If the
  expression's actual value is an integer, it is converted to floating-point. If
  the expression's actual value is a non-numeric string then an error is
  returned.


Tcl_ExprBoolean stores a 0/1 integer value at *booleanPtr. If the
  expression's actual value is an integer or floating-point number, then they
  store 0 at *booleanPtr if the value was zero and 1 otherwise. If the
  expression's actual value is a non-numeric string then it must be one of the
  values accepted by Tcl_GetBoolean such as “yes” or
  “no”, or else an error occurs.


Tcl_ExprString returns the value of the expression as a string stored in
  the interpreter's result.



SEE ALSO

Tcl_ExprLongObj, Tcl_ExprDoubleObj, Tcl_ExprBooleanObj, Tcl_ExprObj



KEYWORDS

boolean, double, evaluate, expression, integer, object, string



  

    7.0
    Tcl