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 a value 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 value
47 that is the result of the ex‐
48 pression.
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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 ex‐
59 pression (e.g. for variables and nested Tcl commands) and to return er‐
60 ror 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 re‐
66 trieved using Tcl_GetObjResult. If an error occurs while executing a
67 Tcl command embedded in the expression then that error will be re‐
68 turned.
69 If the expression is successfully evaluated, then its value is returned
71 in one of four forms, depending on which procedure is invoked. Tcl_Ex‐
72 prLongObj stores an integer value at *longPtr. If the expression's ac‐
73 tual value is a floating-point number, then it is truncated to an inte‐
74 ger. If the expression's actual value is a non-numeric string then an
75 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”, or
87 else an error occurs.
88 If Tcl_ExprObj successfully evaluates the expression, it stores a
90 pointer to the Tcl value containing the expression's value at *resultP‐
91 trPtr. In this case, the caller is responsible for calling Tcl_Decr‐
92 RefCount to decrement the value's reference count when it is finished
93 with the value.
94
97 Tcl_ExprLong, Tcl_ExprDouble, Tcl_ExprBoolean, Tcl_ExprString,
98 Tcl_GetObjResult
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102 boolean, double, evaluate, expression, integer, value, string
103Tcl 8.0 Tcl_ExprLongObj(3)