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.TH Tcl_WrongNumArgs 3 8.0 Tcl "Tcl Library Procedures"
.so man.macros
.BS
.SH NAME
Tcl_WrongNumArgs \- generate standard error message for wrong number of arguments
.SH SYNOPSIS
.nf
\fB#include <tcl.h>\fR
.sp
\fBTcl_WrongNumArgs\fR(\fIinterp, objc, objv, message\fR)
.fi
.SH ARGUMENTS
.AS "Tcl_Obj *const" *message
.AP Tcl_Interp interp in
Interpreter in which error will be reported: error message gets stored
in its result value.
.AP Tcl_Size objc in
Number of leading arguments from \fIobjv\fR to include in error
message.
.AP "Tcl_Obj *const" objv[] in
Arguments to command that had the wrong number of arguments.
.AP "const char" *message in
Additional error information to print after leading arguments
from \fIobjv\fR.  This typically gives the acceptable syntax
of the command.  This argument may be NULL.
.BE
.SH DESCRIPTION
.PP
\fBTcl_WrongNumArgs\fR is a utility procedure that is invoked by
command procedures when they discover that they have received the
wrong number of arguments.  \fBTcl_WrongNumArgs\fR generates a
standard error message and stores it in the result value of
\fIinterp\fR.  The message includes the \fIobjc\fR initial
elements of \fIobjv\fR plus \fImessage\fR.  For example, if
\fIobjv\fR consists of the values \fBfoo\fR and \fBbar\fR,
\fIobjc\fR is 1, and \fImessage\fR is
.QW "\fBfileName count\fR"
then \fIinterp\fR's result value will be set to the following
string:
.PP
.CS
wrong # args: should be "foo fileName count"
.CE
.PP
If \fIobjc\fR is 2, the result will be set to the following string:
.PP
.CS
wrong # args: should be "foo bar fileName count"
.CE
.PP
\fIObjc\fR is usually 1, but may be 2 or more for commands like
\fBstring\fR and the Tk widget commands, which use the first argument
as a subcommand.
.PP
Some of the values in the \fIobjv\fR array may be abbreviations for
a subcommand.  The command
\fBTcl_GetIndexFromObj\fR will convert the abbreviated string value
into an \fIindexObject\fR.  If an error occurs in the parsing of the
subcommand we would like to use the full subcommand name rather than
the abbreviation.  If the \fBTcl_WrongNumArgs\fR command finds any
\fIindexObject\fRs in the \fIobjv\fR array, it will use the full subcommand
name in the error message instead of the abbreviated name that was
originally passed in.  Using the above example, let us assume that
\fIbar\fR is actually an abbreviation for \fIbarfly\fR and the value
is now an \fIindexObject\fR because it was passed to
\fBTcl_GetIndexFromObj\fR.  In this case the error message would be:
.PP
.CS
wrong # args: should be "foo barfly fileName count"
.CE
.SH "REFERENCE COUNT MANAGEMENT"
.PP
The \fIobjv\fR argument to \fBTcl_WrongNumArgs\fR should be the exact
arguments passed to the command or method implementation function that is
calling \fBTcl_WrongNumArgs\fR. As such, all values referenced in it should
have reference counts greater than zero; this is usually a non-issue.
.SH "SEE ALSO"
Tcl_GetIndexFromObj(3)
.SH KEYWORDS
command, error message, wrong number of arguments