C警告：隐含的功能声明＆＃39; htons＆＃39; ＆安培; ＆＃39; ntohs和＆＃39; ＆安培; ＆＃39;兰特＆＃39; - 他们缺少标题吗？

Question

我对C编程很陌生，所以想知道是否有人可以帮助解决这些问题。 （我正在尝试编译别人的代码，我无法对这些代码进行编码）

src/connection.c:79:9: warning: implicit declaration of function 'close' [-Wimplicit-function-declaration
         close(conn->fd);

src/main.c: In function 'main':
src/main.c:37:16: warning: implicit declaration of function 'inet_addr' [-Wimplicit-function-declaration]
     addrs[0] = inet_addr("192.168.252.20"); // Address to bind to


src/server.c: In function 'server_queue_telnet':
src/server.c:93:9: warning: implicit declaration of function 'sleep' [-Wimplicit-function-declaration]
         sleep(1);

src/telnet_info.c: In function 'telnet_info_parse':
src/telnet_info.c:59:12: warning: implicit declaration of function 'inet_addr' [-Wimplicit-function-decla
     addr = inet_addr(addr_str);


src/telnet_info.c:60:12: warning: implicit declaration of function 'htons' [-Wimplicit-function-declarati
     port = htons(atoi(port_str));

src/server.c: In function 'server_queue_telnet':
src/server.c:93:9: warning: implicit declaration of function 'sleep' [-Wimplicit-function-declaration]
         sleep(1);

src/util.c:94:9: warning: implicit declaration of function 'close' [-Wimplicit-function-declaration]
         close(fd);


src/util.c: In function 'util_trim':
src/util.c:161:11: warning: implicit declaration of function 'isspace' [-Wimplicit-function-declaration]
     while(isspace(*str))

我设法通过在相应的文件中包含以下缺少的include语句来修复上述警告。

include <unistd.h>
include <arpa/inet.h> 
include <ctype.h>

然而，以下警告仍然存在，我无法解决哪些包含语句丢失。当我 man ntohs ， man htons 和 man rand 时，我看不到任何应该包含在connection.c和util.c中的指定库文件

src/connection.c: In function 'connection_close':
src/connection.c:62:17: warning: implicit declaration of function 'ntohs' [-Wimplicit-function-declaratio
                 ntohs(conn->info.port),

src/connection.c: In function 'connection_consume_arch':
src/connection.c:485:35: warning: implicit declaration of function 'htons' [-Wimplicit-function-declarati
                 ehdr->e_machine = htons(ehdr->e_machine);

src/util.c: In function 'util_socket_and_bind':
src/util.c:77:18: warning: implicit declaration of function 'rand' [-Wimplicit-function-declaration]
     start_addr = rand() % srv->bind_addrs_len;