擅长:python、mysql、java
<p>稍有不同的方法:</p>
<pre class="lang-py prettyprint-override"><code>tablespecs = "l c d r c l"
def replacenth(string, sub, wanted, n):
count = 0
out = ""
for c in string:
if c in sub:
count += 1
if count == n:
out += wanted
count = 0
out += c
return out
res = replacenth(tablespecs, "lcr", "here: ", 3)
assert res == "l c d here: r c l", res
</code></pre>