grep: display filename once, then display context with line numbers

I would change a few things about.

find_code() { 
    # assign all arguments (not just the first ${1}) to MATCH
    # so find_code can be used with multiple arguments:
    #    find_code errorCode
    #    find_code = 1111
    #    find_code errorCode = 1111
    MATCH="$@" 

    # For each file that has a match in it (note I use `-l` to get just the file name
    # that matches, and not the display of the matching part) I.e we get an output of:
    #
    #       srcdir/matching_file.c
    # NOT:
    #       srcdir/matching_file.c:       errorCode = 1111
    #
    grep -lr "$MATCH" ${SRCDIR} | while read file 
    do 
        # echo the filename
        echo ${file}
        # and grep the match in that file (this time using `-h` to suppress the 
        # display of the filename that actually matched, and `-n` to display the 
        # line numbers)
        grep -nh -A5 -B5 "$MATCH" "${file}"
    done 
}

You could use find with two -execs, the second one will be executed only if the first one is successful, e.g. searching only in .cpp, .c and .cs files:

find_code() {
find ${SRCDIR} -type f \
\( -name \*.cpp -o -name \*.c -o -name \*.cs \) \
-exec grep -l "= ${1}" {} \; -exec grep -n -C5 "= ${1}" {} \;
}

so the first grep prints the filenames that contain your pattern and the second one will print the matching lines+context, numbered, from the respective files.