如何用strtok检测空行

Question

我正在尝试将页眉与页脚分开，用空行分隔，即使用字符串“\r\n\r\n”。

我尝试使用 strtok 和分隔符 "\r\n\r\n"，如下面的代码片段所示。

#include <stdio.h>
#include <string.h>

int main() {
    char get[1024] = "HTTP/1.1 200 OK\r\nDate: Tue, 23 Jul 2019 22:52:44 GMT\r\n"
                     "Server: Apache/2.4.7 (Ubuntu)\r\n"
                     "Last-Modified: Wed, 18 Aug 2004 23:07:08 GMT\r\n"
                     "ETag: \"164-3e1f5b9a57f00\"\r\n"
                     "Accept-Ranges: bytes\r\n"
                     "Content-Length: 356\r\n"
                     "Vary: Accept-Encoding\r\n"
                     "Content-Type: text/html\r\n"
                     "\r\n"
                     "<html><head><title>Temporary Page</title></head><body><center><h1>New Account Temporary Page</h1>Welcome to yet another new account at Hurricane Electric.<p><h2>Come Back Soon!</h2>The New Account Owner Will Be Putting Something Interesting Here!</center><hr>Space Provided By <a href=\"http://www.he.net\">Hurricane Electric</a></body></html>";

    char *html;

    html = strtok(get, "\r\n\r\n");
    printf("Header:\n\n%s\n\n", html);
    html = strtok(NULL, "\r\n\r\n");
    printf("HTML:\n\n%s\n\n", html);

    return 1;
}

我希望输出是打印出的页眉，然后是 HTML 页脚。

但输出是：

Header:

HTTP/1.1 200 OK

HTML:

Date: Tue, 23 Jul 2019 22:52:44 GMT

似乎 strtok 正在使用 "\r\n" 而不是 "\r\n\r\n" 进行分隔。我该如何解决这种奇怪的行为？

Answer 1

strtok 分隔符参数不是字符序列。它是分隔您的标记的可能字符的列表。

所以在分隔符字符串中传递重复的字符并没有达到预期的效果。

为了说服自己，将分隔符替换为 GMT，您会看到 header 现在是 H，因为 strtok 从 [=16= 标记化而来], 因为它在定界符列表中。

另一种方法（dirty/no 错误检查）是使用 strstr 定位分隔符，将零放在那里，然后打印两个字符串

#include <stdio.h>
#include <string.h>

int main ()
{

    char get[1024] = "HTTP/1.1 200 OK\r\nDate: Tue, 23 Jul 2019 22:52:44 GMT\r\nServer: Apache/2.4.7 (Ubuntu)\r\nLast-Modified: Wed, 18 Aug 2004 23:07:08 GMT\r\nETag: \"164-3e1f5b9a57f00\"\r\nAccept-Ranges: bytes\r\nContent-Length: 356\r\nVary: Accept-Encoding\r\nContent-Type: text/html\r\n\r\n<html><head><title>Temporary Page</title></head><body><center><h1>New Account Temporary Page</h1>Welcome to yet another new account at Hurricane Electric.<p><h2>Come Back Soon!</h2>The New Account Owner Will Be Putting Something Interesting Here!</center><hr>Space Provided By <a href=\"http://www.he.net\">Hurricane Electric</a></body></html>";

    const char *delim = "\r\n\r\n";

    char *html;

    html = strstr(get, delim);  // should test for NULL ...
    html[0] = '[=10=]';
    printf("Header:\n\n%s\n\n", get);
    printf("HTML:\n\n%s\n\n", html+strlen(delim));

    return 1;

}

输出：

Header:

HTTP/1.1 200 OK
Date: Tue, 23 Jul 2019 22:52:44 GMT
Server: Apache/2.4.7 (Ubuntu)
Last-Modified: Wed, 18 Aug 2004 23:07:08 GMT
ETag: "164-3e1f5b9a57f00"
Accept-Ranges: bytes
Content-Length: 356
Vary: Accept-Encoding
Content-Type: text/html

HTML:

<html><head><title>Temporary Page</title></head><body><center><h1>New Account Temporary Page</h1>Welcome to yet another new account at Hurricane Electric.<p><h2>Come Back Soon!</h2>The New Account Owner Will Be Putting Something Interesting Here!</center><hr>Space Provided By <a href="http://www.he.net">Hurricane Electric</a></body></html>

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