Run-length encoding: Difference between revisions

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 : Input:  <code>WWWWWWWWWWWWBWWWWWWWWWWWWBBBWWWWWWWWWWWWWWWWWWWWWWWWBWWWWWWWWWWWWWW</code>
 : Output: <code>12W1B12W3B24W1B14W</code>
+=={{header|AWK}}==
+{{works with|gawk}}
+It works with "textual" input. Lines containing numbers are skipped, since they can't be represented in a not ambiguous way in this implementation (e.g. "11AA" would be encoded as "212A", which would be decoded as A repeated 212 times!)
+'''Encoding'''
+<lang awk>BEGIN {
+ FS=""
+}
+/^[^0-9]+$/ {
+  cp = $1; j = 0
+  for(i=1; i <= NF; i++) {
+    if ( $i == cp ) {
+      j++;
+    } else {
+      printf("%d%c", j, cp)
+      j = 1
+    }
+    cp = $i
+  }
+  printf("%d%c", j, cp)
+}</lang>
+'''Decoding'''
+<lang awk>BEGIN {
+  RS="[0-9]+[^0-9]"
+  final = "";
+}
+{
+  match(RT, /([0-9]+)([^0-9])/, r)
+  for(i=0; i < int(r[1]); i++) {
+    final = final r[2]
+  }
+}
+END {
+  print final
+}</lang>
 =={{header|C}}==