深入理解计算机系统 CSAPP 家庭作业11.10
A:
//home.html
<form action="/cgi-bin/adder" method="GET"><ul><li><label for="n1">n1:</label><input type="text" id="n1" name="n1" /> //name的值决定页面提交后，生成的地址。</li><li><label for="n2">n2:</label><input type="text" id="n2" name="n2" /> //name的值决定页面提交后，生成的地址。</li><li class="button"><button type="submit">Send</button></li></ul>
</form>home.html放在根目录.那样访问127.0.0.1:XX的时候会直接跳转到这个提交数据的页面.
html文件中的name决定用户点击Send按钮后跳转的地址后的参数名.
//adder.c
#include "csapp.h"int main(void) {char *buf, *p;char arg1[MAXLINE], arg2[MAXLINE], content[MAXLINE];int n1=0, n2=0;/* Extract the two arguments */if ((buf = getenv("QUERY_STRING")) != NULL) {p = strchr(buf, '&');*p = '\0';sscanf(buf,"n1=%d",&n1); //此处决定读取地址的格式sscanf(p+1,"n2=%d",&n2); //此处决定读取地址的格式}/* Make the response body */sprintf(content, "Welcome to add.com: ");sprintf(content, "%sTHE Internet addition portal.\r\n<p>", content);sprintf(content, "%sThe answer is: %d + %d = %d\r\n<p>", content, n1, n2, n1 + n2);sprintf(content, "%sThanks for visiting!\r\n", content);/* Generate the HTTP response */printf("Connection: close\r\n");printf("Content-length: %d\r\n", (int)strlen(content));printf("Content-type: text/html\r\n\r\n");printf("%s", content);fflush(stdout);exit(0);
}adder.c文件中的sscanf中的按格式输入是"n1=%d",这里是和html文件对应的. .adder程序是从html文件生成的地址中读取变量的.