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Tcl_ExprLong(3) Tcl Library Procedures Tcl_ExprLong(3) ______________________________________________________________________________## NAME

Tcl_ExprLong, Tcl_ExprDouble, Tcl_ExprBoolean, Tcl_ExprString - evaluate an expression## SYNOPSIS

#include<tcl.h>intTcl_ExprLong(interp,expr,longPtr) intTcl_ExprDouble(interp,expr,doublePtr) intTcl_ExprBoolean(interp,expr,booleanPtr) intTcl_ExprString(interp,expr)## ARGUMENTS

Tcl_Interp*interp(in) Interpreter in whose context to evaluateexpr. 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 theexprargument and return the result in one of four different forms. The expression can have any of the forms accepted by theexprcommand. Note that these procedures have been largely replaced by the value- based proceduresTcl_ExprLongObj,Tcl_ExprDoubleObj,Tcl_ExprBooleanObj, andTcl_ExprObj. Those value-based procedures evaluate an expression held in a Tcl value instead of a string. The value argument can retain an internal representation that is more efficient to execute. Theinterpargument 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_OKmeans the expression was successfully evaluated, andTCL_ERRORmeans that an error occurred while evaluating the expression. IfTCL_ERRORis 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_ExprLongstores 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_ExprDoublestores 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_ExprBooleanstores 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*booleanPtrif 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 byTcl_GetBooleansuch as "yes" or "no", or else an error occurs.Tcl_ExprStringreturns 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, value, string Tcl 7.0 Tcl_ExprLong(3)

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