Shulou(Shulou.com)06/01 Report--

Network order, host order learning

Network order, host order is always confused. It needs to be tidied up.

A thousand words are not as real as the code. Haha, just do it.

# include # include # include int host_order () {unsigned long a = 0x12345678; unsigned char * p = (unsigned char *) (& a); printf ("host byte order:% 0x% 0x% 0x% 0x\ n", p [0], p [1], p [2], p [3]); unsigned long b = htonl (a); p = (unsigned char *) (& b) Printf ("Network byte order:% 0x% 0x% 0x\ n", p [0], p [1], p [2], p [3]); return 0;} int net_order () {struct in_addr ipaddr; unsigned long addr = inet_addr ("192.168.1.100"); unsigned char * p = (unsigned char *) (& addr); printf ("addr =% u\ n", addr) Printf ("% 0x% 0x% 0x: inet_addr 192.168.1.100\ n", p [0], p [1], p [2], p [3]); printf ("% d% d: inet_addr 192.168.1.100\ n", p [0], p [1], p [2], p [3]); unsigned long addr_host = ntohl (addr); p = (unsigned char *) (& addr_host) Printf ("% 0x% 0x% 0x: inet_addr ntohl 192.168.1.100\ n", p [0], p [1], p [2], p [3]); printf ("% d% d: inet_addr ntohl 192.168.1.100\ n", p [0], p [1], p [2], p [3]); printf ("addr_host =% u\ n", addr_host); return 0 } int main () {int ret = 0; / / ret = host_order (); ret = net_order (); return ret;}

Compile it.

Gcc-g-o test_order test_order.c

Run.

[root@localhost test] #. / test_order addr = 1677830336 c0a8 1 64: inet_addr 192.168.1.100192 168 1100: inet_addr 192.168.1.10064 1 a8 c0: inet_addr ntohl 192.168.1.100100 1168 192: inet_addr ntohl 192.168.1.100addr_host = 3232235876

Clear and clear. It helps to understand quickly.

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