Regular expressions: Difference between revisions

=={{header|ALGOL 68}}==

The routines ''grep in strings'' and ''sub in string'' are not part of [[ALGOL 68]]'s standard prelude.

<!-- {{does not work with|ALGOL 68|Standard - grep/sub in string are not part of the standard's prelude. }} -->

{{works with|ALGOL 68G|Any - tested with release mk15-0.8b.fc9.i386}}

<lang algol>INT match=0, no match=1, out of memory error=2, other error=3;

STRING str := "i am a string";

# Match: #

STRING m := "string$";

INT start, end;

IF grep in string(m, str, start, end) = match THEN printf(($"Ends with """g""""l$, str[start:end])) FI;

# Replace: #

IF sub in string(" a ", " another ",str) = match THEN printf(($gl$, str)) FI;</lang>

Output:

<pre>

Ends with "string"

i am another string

</pre>

Standard ALGOL 68 does have an primordial form of pattern matching

called a '''format'''. This is designed to extract values from input data.

But it can also be used for outputting (and transputting) the original data.

{{works with|ALGOL 68|Standard - But declaring ''book'' as [][][]'''char''' }}

{{works with|ALGOL 68G|Any - tested with release mk15-0.8b.fc9.i386}}

For example:<lang algol>

FORMAT pattern = $ddd" "c("cats","dogs")$;

FILE file; STRING book; associate(file, book);

on value error(file, (REF FILE f)BOOL: stop);

on format error(file, (REF FILE f)BOOL: stop);

book := "100 dogs";

STRUCT(INT count, type) dalmatians;

getf(file, (pattern, dalmatians));

print(("Dalmatians: ", dalmatians, new line));

count OF dalmatians +:=1;

printf(($"Gives: "$, pattern, dalmatians, $l$))</lang>

Output:

<pre>

Dalmatians: +100 +2

Gives 101 dogs

</pre>

=={{header|C}}==