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32 .\" @(#)xstr.1 8.2 (Berkeley) 12/30/93
40 .Nd "extract strings from C programs to implement shared strings"
49 utility maintains a file
51 into which strings in component parts of a large program are hashed.
52 These strings are replaced with references to this common area.
53 This serves to implement shared constant strings, most useful if they
56 The following options are available:
57 .Bl -tag -width indent
59 Read from the standard input.
61 Extract the strings from the C source
66 string references by expressions of the form (&xstr[number])
68 An appropriate declaration of
70 is prepended to the file.
71 The resulting C text is placed in the file
74 The strings from this file are placed in the
76 data base if they are not there already.
77 Repeated strings and strings which are suffixes of existing strings
78 do not cause changes to the data base.
83 After all components of a large program have been compiled a file
87 space can be created by a command of the form
88 .Bd -literal -offset indent
94 should then be compiled and loaded with the rest
96 If possible, the array can be made read-only (shared) saving
97 space and swap overhead.
101 utility can also be used on a single file.
103 .Bd -literal -offset indent
111 as before, without using or affecting any
113 file in the same directory.
115 It may be useful to run
117 after the C preprocessor if any macro definitions yield strings
118 or if there is conditional code which contains strings
119 which may not, in fact, be needed.
120 An appropriate command sequence for running
122 after the C preprocessor is:
124 .Bd -literal -offset indent -compact
125 cc \-E name.c | xstr \-c \-
132 utility does not touch the file
134 unless new items are added, thus
138 unless truly necessary.
140 .Bl -tag -width /tmp/xsxx* -compact
146 C source for definition of array `xstr'
148 temp file when `xstr name' does not touch
159 If a string is a suffix of another string in the data base,
160 but the shorter string is seen first by
162 both strings will be placed in the data base, when just
163 placing the longer one there will do.