下列常量由此擴展定義，且僅在此擴展編譯入 PHP 或在運行時(shí)動(dòng)態(tài)載入時(shí)可用。
GMP_ROUND_ZERO
(int)
GMP_ROUND_PLUSINF
(int)
GMP_ROUND_MINUSINF
(int)
GMP_MSW_FIRST
(int)
GMP_LSW_FIRST
(int)
GMP_LITTLE_ENDIAN
(int)
GMP_BIG_ENDIAN
(int)
GMP_NATIVE_ENDIAN
(int)
GMP_VERSION
(string)