【造成原因】：Because PHP’s integer type is signed, and many IP addresses will result in negative integers.
【解决办法】：其官方手册中提到，可以“you need to use the “%u” formatter of sprintf() or printf() to get the string representation of the unsigned IP address”
即，printf( ‘%u’, ip2long( ‘IP地址’ ) );
或者将其先转换为二进制然后在转换为十进制，b
