[問題] Socket接收資料處理

看板C_and_CPP (C/C++)作者TampaBayRays (光芒今年拿冠軍)時間7年前 (2018/11/10 10:08)推噓19(19推 0噓 26→)

留言45則, 4人參與討論串1/1

開發平台(Platform): (Ex: Win10, Linux, ...) Mac OS Mojave 編譯器(Ex: GCC, clang, VC++...)+目標環境(跟開發平台不同的話需列出) G++ 額外使用到的函數庫(Library Used): (Ex: OpenGL, ...) 問題(Question)：我做了一個server想接收client的指令去執行，但是我將指令傳到 server時，server無法判斷指令，所以我先做了一個小程式，把收到的指令印出來，並判斷他是不是ls，結果還是不行餵入的資料(Input)： ls 預期的正確結果(Expected Output)：印出recevied:'ls' yes 錯誤結果(Wrong Output)： server: client connected with ip address: 0.0.0.0 received: 'ls ' received: 'ls ' client: telnet 0.0.0.0 8877 Trying 0.0.0.0... Connected to 0.0.0.0. Escape character is '^]'. ls ls 程式碼(Code)：(請善用置底文網頁, 記得排版，禁止使用圖檔) int main(int argc, char *argv[]) { int SERVER_PORT = 8877; struct sockaddr_in server_address; memset(&server_address, 0, sizeof(server_address)); server_address.sin_family = AF_INET; server_address.sin_port = htons(SERVER_PORT); server_address.sin_addr.s_addr = htonl(INADDR_ANY); int listen_sock; if ((listen_sock = socket(PF_INET, SOCK_STREAM, 0)) < 0) { printf("could not create listen socket\n"); return 1; } if ((bind(listen_sock, (struct sockaddr *)&server_address,sizeof(server_address))) < 0) { printf("could not bind socket\n"); return 1; } int wait_size = 16; // maximum number of waiting clients, after which // dropping begins if (listen(listen_sock, wait_size) < 0) { printf("could not open socket for listening\n"); return 1; } struct sockaddr_in client_address; socklen_t client_address_len = 0; while (true) { int sock; if ((sock =accept(listen_sock, (struct sockaddr *)&client_address, &client_address_len)) < 0) { printf("could not open a socket to accept data\n"); return 1; } int n = 0; int len = 0, maxlen = 100; char buffer[maxlen]; char *pbuffer = buffer; printf("client connected with ip address: %s\n",inet_ntoa(client_address.sin_addr)); while ((n = recv(sock, pbuffer, maxlen, 0)) > 0) { pbuffer += n; maxlen -= n; len += n; printf("received: '%s'\n", buffer); string line=buffer; line=line.substr(0,n); printf("received: '%s'\n", line.c_str()); if (!strcmp(buffer,"ls")){ printf("yes"); } if (line=="ls"){ printf("yes"); } send(sock, buffer, len, 0); } close(sock); } close(listen_sock); return 0; } 補充說明(Supplement)：看起來傳回去的東西是沒問題的，但是為什麼我server收到的東西不太對。 1.右括號被換行了 2.沒有判斷出我傳的是ls(應該要印出yes) 請各位大大救救我QQ 感謝！ -- ╭ ◢█◤ ╭══╮ ╭ ◢█ ◣ theanswer3╮ ║ █▌╰═════════════════╯ ★ ╰══╯ █▌ █ ╴◤ / ║ ║ ◢█◣ ◢█◣ ◢█◣ ◢█◣ ◢◢◣ ◢ ◢█◣ ◢ ◤ ￣╱＞ ║ ║ █▌ ◢ █▌█ ███ █▌█ █▌█ █◤ █ █◢█ ◥ ◣ ║ ║◢███◤◥█◤ ◥▌◤ ◥██ ◥█◤ █ ◤ ◥◤◥ █▌ █ ╰/ ║ ╰═════════════▅◤═════════════ ◥█ ◤ ═════╯ -- ※ 發信站: 批踢踢實業坊(ptt.cc), 來自: 59.127.199.39 ※ 文章網址: https://www.ptt.cc/bbs/C_and_CPP/M.1541815726.A.2E0.html

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bigbite

11/10 11:01, 7年前 , 1^F

11/10 11:01, 1^F

我也覺得是這樣，所以我有用一個string line去接，然後line=line.substr(0,n)，如果是這樣那感覺第二個yes應該會印出來？然後如果我改成line=line.substr(0,n-1)那會變成印出 client connected with ip address: 0.0.0.0 received: 'ls ' 'eceived: 'ls 我無法理解為什麼右括號會蓋掉第一個字母.....

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