This a fast floating point to string conversion function. Avoids the use of unsafe sprintf function. Works with float and double types. Correctly manages +inf, -inf, nnan (not a number).-This is a fast floating point to string conversion function. Av

该函数能够完成把字符串str中的所有子串find_str都替换成字符串replace_str，返回值为替换的次数。-The function can be completed in the string STR of all substrings find_str are replaced by a string replace_str, the return value of the number of substitutions.