string 将指定的字符或字符串全部替换成特定的字符或字符串

string&   replace_all_distinct(string&   str, const   string&   old_value, const   string&   new_value)
{
for (string::size_type pos(0); pos != string::npos; pos += new_value.length())  
{
if ((pos = str.find(old_value, pos)) != string::npos)
str.replace(pos, old_value.length(), new_value);
else  
break;
}
return   str;
}