regex - Need SED or AWK script to do strlen optimization -

i need little cause touch sed or awk. i'm trying replace

string1.append("hello");   // regexp find is: \w*\.append\(".*"\)  

with

string1.append("hello", 5);  // note has figure out length of "hello" 

and need search , replace across hundreds of thousands of files. , "hello anything... including "\n\n\n" should 3 not 6. example:

s.append("\n\n\n");  ---> s.append("\n\n\n", 3); 

thanks in advance help... i'm thinking need awk i'm reading tutorial basics of awk right now...

since want run on files containing code, here's example of full functionality:

$ cat file foo() {    string1.append("hello");    if (bar) {       s.append("\n\n\n");    }    else {       s.append("\n\\n\n\\\n");    } } $ $ cat tst.awk match($0,/[[:alnum:]_]+\.append\(".*"\)/) {     split(substr($0,rstart,rlength), orig, /"/)      head = substr($0,1,rstart-1) orig[1]     tail = orig[3] substr($0,rstart+rlength)      tgt = orig[2]     gsub(/[\\][\\]/,"x",tgt)     gsub(/[\\]/,"",tgt)      $0 = sprintf("%s\"%s\", %d%s", head, orig[2], length(tgt), tail) } { print } $ $ awk -f tst.awk file foo() {    string1.append("hello", 5);    if (bar) {       s.append("\n\n\n", 3);    }    else {       s.append("\n\\n\n\\\n", 6);    } } 

i replaced "\w" example in original posted question posix equivalent "[[:alnum:]_]" portability. "\w" work gnu awk , other tools, not tools , not awks.