[ramsan] This code tries to convert an old pre-ANSI C file to an ANSI C file. It will
try to change things like:

 int 
 ParseGLFunc (interp, argc, argv, nArg)
     Tcl_Interp *interp;
     int argc;
     char *argv [];
     int *nArg;
 {
    ....
 }

to something like:

 int ParseGLFunc( Tcl_Interp *interp, int objc,Tcl_Obj *CONST objv[], int *nArg)

Of course, without guarantees. Please, do correct it if you can improve.
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Your example is incorrect, it shows the difference between the old (pre 8.x) string based tcl command interface and the new Tcl_Obj based (8.x) style commands. If i remember correct it's the 8.4 version with CONST. This has nothing to do with ANSI C and not ANSI C. Didn't look at your code below, to see if it does something else...
[Michael Schlenker]  

----
 set filein {C:\path\to\file.c.old}
 set fileout {C:\path\to\file.c}
 
 set fin [open $filein r]
 set contents [read $fin]
 close $fin
 
 set funcname {\s*(\w+)\s*}
 set varname {\s*(\w+)\s*}
 set typename {\s*\w+[\s*&]*}
 
 for { set i 1 } { $i < 10 } { incr i } {
     set rex "$funcname\\("
     for { set j 1 } { $j <= $i } { incr j } {
         if { $j > 1 } { append rex "," }
         append rex $varname
     }
     append rex "\\)"
     for { set j 1 } { $j <= $i } { incr j } {
         append rex "($typename\\[expr {$j+1}]\[]\[\\s]*)\\s*;"
     }
     while 1 {
         set idxs [regexp -inline -indices $rex $contents]
         if { $idxs == "" } { break }
         set contents_new [string range $contents 0 [expr [lindex [lindex $idxs 0] 0]-1]]
         append contents_new " [eval string range [list $contents] [lindex $idxs 1]]("
         for { set j 1 } { $j <= $i } { incr j } {
             set ipos [expr {$j+$i+1}]
             regsub -all {\s+} [eval string range [list $contents] [lindex $idxs $ipos]] { } arg
             if { $j > 1 } { append  contents_new "," }
             append contents_new $arg
         }
         append contents_new ")[string range $contents [expr [lindex [lindex $idxs 0] 1]+1] end]"
         set contents $contents_new
     }
 }
 set fout [open $fileout w]
 puts $fout $contents
 close $fout