1Tcl_ExprLongObj(3) Tcl Library Procedures Tcl_ExprLongObj(3)
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8 Tcl_ExprLongObj, Tcl_ExprDoubleObj, Tcl_ExprBooleanObj, Tcl_ExprObj -
9 evaluate an expression
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12 #include <tcl.h>
13 int
15 Tcl_ExprLongObj(interp, objPtr, longPtr)
16 int
18 Tcl_ExprDoubleObj(interp, objPtr, doublePtr)
19 int
21 Tcl_ExprBooleanObj(interp, objPtr, booleanPtr)
22 int
24 Tcl_ExprObj(interp, objPtr, resultPtrPtr)
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27 Tcl_Interp *interp (in) Interpreter in whose context to
28 evaluate objPtr.
29 Tcl_Obj *objPtr (in) Pointer to an object containing
31 the expression to evaluate.
32 long *longPtr (out) Pointer to location in which to
34 store the integer value of the
35 expression.
36 int *doublePtr (out) Pointer to location in which to
38 store the floating-point value
39 of the expression.
40 int *booleanPtr (out) Pointer to location in which to
42 store the 0/1 boolean value of
43 the expression.
44 Tcl_Obj **resultPtrPtr (out) Pointer to location in which to
46 store a pointer to the object
47 that is the result of the
48 expression.
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50
53 These four procedures all evaluate an expression, returning the result
54 in one of four different forms. The expression is given by the objPtr
55 argument, and it can have any of the forms accepted by the expr com‐
56 mand.
57 The interp argument refers to an interpreter used to evaluate the
59 expression (e.g. for variables and nested Tcl commands) and to return
60 error information.
61 For all of these procedures the return value is a standard Tcl result:
63 TCL_OK means the expression was successfully evaluated, and TCL_ERROR
64 means that an error occurred while evaluating the expression. If
65 TCL_ERROR is returned, then a message describing the error can be
66 retrieved using Tcl_GetObjResult. If an error occurs while executing a
67 Tcl command embedded in the expression then that error will be
68 returned.
69 If the expression is successfully evaluated, then its value is returned
71 in one of four forms, depending on which procedure is invoked.
72 Tcl_ExprLongObj stores an integer value at *longPtr. If the expres‐
73 sion's actual value is a floating-point number, then it is truncated to
74 an integer. If the expression's actual value is a non-numeric string
75 then an error is returned.
76 Tcl_ExprDoubleObj stores a floating-point value at *doublePtr. If the
78 expression's actual value is an integer, it is converted to floating-
79 point. If the expression's actual value is a non-numeric string then
80 an error is returned.
81 Tcl_ExprBooleanObj stores a 0/1 integer value at *booleanPtr. If the
83 expression's actual value is an integer or floating-point number, then
84 they store 0 at *booleanPtr if the value was zero and 1 otherwise. If
85 the expression's actual value is a non-numeric string then it must be
86 one of the values accepted by Tcl_GetBoolean such as ``yes'' or ``no'',
87 or else an error occurs.
88 If Tcl_ExprObj successfully evaluates the expression, it stores a
90 pointer to the Tcl object containing the expression's value at
91 *resultPtrPtr. In this case, the caller is responsible for calling
92 Tcl_DecrRefCount to decrement the object's reference count when it is
93 finished with the object.
94
97 Tcl_ExprLong, Tcl_ExprDouble, Tcl_ExprBoolean, Tcl_ExprString,
98 Tcl_GetObjResult
99
102 boolean, double, evaluate, expression, integer, object, string
103Tcl 8.0 Tcl_ExprLongObj(3)