//Convert the characters of the IP dotted address back to the IP v4 format address
int ip2long(string ip_address)
//Convert the IP v4 format address back to the string of the IP dotted address
string long2ip(int proper_address)
//Get the environment variable varname. If successful, the variable value will be returned. If it fails, false will be returned.
string getenv(string varname)
//Used to set Set the system environment
void putenv(string setting)
//Get the owner name of the current PHP script
string get_current_user(void)
//Call the user function specified by function_name
string get_cfg_var(string function_name[,mixed parrameter[,mixed...]])
//Return the port (protocol) associated with service, which must be TCP or UDP
int getservbyname(string service,string protocol)
//Returns the service name (protocol) associated with port, which must be TCP or UDP
string getservbyport(int port,string protocol)
// Take the absolute value
mixed abs(mixed number)
//Square root
float sqrt(float arg)
//The power of the natural logarithm e
float exp(float arg)
//Return pi
double pi(void)
//Round
double round(double val)
// Calculate the smallest integer greater than the specified number
int ceil(float number)
//Calculate the largest integer less than the specified number
int floor(float number)
//Get the maximum value
mixed max(mixed arg1,mixed arg2...mixed argn)
//Take the minimum value
mixed min(mixed arg1,mixed arg2...mixed argn)
//Get random numbers
int rand([int min],[int max])
//Number system conversion
string base_convert(string number,int frombase,int tobase )
//Format number string
string number_format(float number,int[decimals],string[decpoint],string[thounsands_sep])