得到（）没有得到excuted [英] gets() doesn't get excuted

问题描述

在我的源代码codeS，还有下面的代码片段：

in my source codes, there is the following snippet:

    while ((cmd=getchar()) != EOF)
    {   
            switch(cmd)
            {   
                    case '1':
                            printf("pls input the data to be sent: \n");
                            char data[100];
                            gets(data);
                            send_data(sd_cli, data, strlen(data), &svr_addr);          
                            pcap_packet = pcap_next(pcap_handler, &pcap_header);
                            if(pcap_packet !=NULL)
                                    printf("capture one packet with length of %d\n", pcap_header.len);
                            analyze_pcap_pkt(pcap_packet, &ipid, &temp_port1, &temp_port2, &seq, &ack_seq);
                            temp_seq = seq;
                            seq = ack_seq;
                            ack_seq = temp_seq;

                            ipid++;
                            break;
                    case '2':
                            printf("old ack is %x\n", ack_seq);
                            printf("pls input the seq plus amount: \n");
                            char amount[6];
                            gets(amount);
                            ack_seq= ack_seq+atoi(amount);
                            printf("new akc is %x\n", ack_seq);
                            send_ack(sd_raw, &svr_addr, lo_ipaddr, svr_ipaddr, htons(src_port), htons(dst_port), htons(ipid), htonl(seq), htonl(ack_seq));
                            ipid++;
                            break;
                    case '4':
                            send_rst(sd_raw, &svr_addr, lo_ipaddr, svr_ipaddr, htons(ipid), htons(src_port), htons(dst_port), htonl(seq), htonl(ack_seq));
                            break;
            }   
    }   

当我运行该程序，输出结果是：

when I run the program, the output is:

old ack_seq is ab2429c6
pls input the seq plus amount: 
new ack_seq is ab2429c6
sendto ack packet

：无效的参数

BTW：在 send_ack ， send_rst 函数使用原始套接字来发送数据包。
 似乎获得（）功能没有得到excuted，有什么不对呢？
谢谢！

BTW: the send_ack, send_rst functions use raw socket to send packets. it seems that the gets() function doesn't get excuted, what is wrong with this? thanks!

推荐答案

呼叫的getchar（）; 你打电话之前获得。既然这样，你输入两个字符，命令号和一个换行符。因此，获得读入一个空行，剥离换行，阵列存储在一个空字符串。

Call getchar(); before you call gets. As it stands, you input two characters, the command number and a newline. So gets reads a blank line, strips the newline, and stores an empty string in your array.

正如在其他的答案指出，获得是因为它的安全风险pcated德$ P $，但是这并不涉及您的问题。

As noted in the other answers, gets is deprecated because of its security risk, but this doesn't relate to your problem.

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