Category : C Source Code
Archive   : CSRC2.ZIP
Filename : TRANSL.C

 
Output of file : TRANSL.C contained in archive : CSRC2.ZIP
/*
* t r a n s l . c
*/

/*)LIBRARY
*/

#ifdef DOCUMENTATION

title translate Character Translation Functions
index Do character translation
index Clear character translation table
index Set character translation table

synopsis

clrttab(t,max)
char t[];
int max;

setttab(t,from,to)
char t[];
char *from;
char *to;

translate(t,s)
char t[];
char *s;

description

These functions provide a character translation facility. translate()
does the actual translation; clrttab() and setttab() set up a table
for use with translate().

A translation table t[] is simple a byte array; translate() will map
character c into t[c]. However, if t[c] is 0, it does not appear
in the output - i.e., translating a character to null deletes it.
t can be from 1 to 256 bytes in length. Only clrttab(), however,
accepts the length of t as an argument; the other functions assume
that any character they try to translate can be safely looked up in
t. Usually, t is 128 bytes long and only legal ASCII characters,
without parity, are passed, or 256 to support extended ASCII.

clrttab(t,max) clears a table to the null translation - i.e., t will
translate every character into itself. t is assumed to be max+1 bytes
long (so that it can translate characters with values from 0 to max).

setttab(t,from,to) modifies t so that characters in from are mapped
into corresponding characters in to. If from is longer than to, any
"excess" characters will map to 0, i.e., be deleted. Thus, the calls

clrttab(t,127);
setttab(t,"abcdewxyz","ABCDE");

create a table that maps a,b,c,d and e into their upper-case
equivalents and deletes w,x,y and z.

Note: It is meaningless to set up a translation for the 0 byte;
t[0] is never used.

translate(t,s) translates string s using table t. s itself is
modified. s will be properly null-trailed, but may be shorter than
it was as passed (if any of its characters are deleted).

See also replace() for a simple way to use these functions.

bugs

author

Jerry Leichter

#endif

/*
*)EDITLEVEL=02
* Edit history
* 0.0 30-Jun-81 JSL Invention
*/

#define EOS '\0'

clrttab(t,max)
register char t[];
register int max;
{ register int i;

for (i = 0; i <= max; i++)
t[i] = i;
}

setttab(t,from,to)
register char t[];
register char *from;
register char *to;
{
while (*from)
{ t[*from++] = *to;
if (*to)
to++;
}
}

translate(t,s)
register char t[];
register char *s;
{ register char *r; /* Where translated char goes */

r = s;
while (*s)
if (*r = t[*s++]) /* Non-null - real translation */
r++;
*r = EOS;
}


  3 Responses to “Category : C Source Code
Archive   : CSRC2.ZIP
Filename : TRANSL.C

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