example/maxconnects: set maxconnect example

Closes curl#11343

docs/examples/Makefile.inc

@@ -77,6 +77,7 @@ check_PROGRAMS = \
   imap-store \
   imap-tls \
   ipv6 \
+  maxconnects  \
   multi-app \
   multi-debugcallback \
   multi-double \

docs/examples/maxconnects.c

@@ -0,0 +1,66 @@
+/***************************************************************************
+ *                                  _   _ ____  _
+ *  Project                     ___| | | |  _ \| |
+ *                             / __| | | | |_) | |
+ *                            | (__| |_| |  _ <| |___
+ *                             \___|\___/|_| \_\_____|
+ *
+ * Copyright (C) James Fuller, <jim@webcomposite.com>, et al.
+ *
+ * This software is licensed as described in the file COPYING, which
+ * you should have received as part of this distribution. The terms
+ * are also available at https://curl.se/docs/copyright.html.
+ *
+ * You may opt to use, copy, modify, merge, publish, distribute and/or sell
+ * copies of the Software, and permit persons to whom the Software is
+ * furnished to do so, under the terms of the COPYING file.
+ *
+ * This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
+ * KIND, either express or implied.
+ *
+ * SPDX-License-Identifier: curl
+ *
+ ***************************************************************************/
+/* <DESC>
+ * Set maximum number of persistent connections to 1.
+ * </DESC>
+ */
+#include <stdio.h>
+#include <curl/curl.h>
+
+int main(void)
+{
+  CURL *curl;
+  CURLcode res;
+
+  curl = curl_easy_init();
+  if(curl) {
+    const char *urls[] = { "https://example.com",
+      "https://curl.se",
+      "https://www.example/",
+      NULL /* end of list */
+    };
+    int i = 0;
+
+    /* Change the maximum number of persistent connection   */
+    curl_easy_setopt(curl, CURLOPT_MAXCONNECTS, 1L);
+
+    curl_easy_setopt(curl, CURLOPT_VERBOSE, 1L);
+
+    /* loop over the URLs */
+    while(urls[i]) {
+      curl_easy_setopt(curl, CURLOPT_URL, urls[i]);
+
+      /* Perform the request, res will get the return code */
+      res = curl_easy_perform(curl);
+      /* Check for errors */
+      if(res != CURLE_OK)
+        fprintf(stderr, "curl_easy_perform() failed: %s\n",
+                curl_easy_strerror(res));
+      i++;
+    }
+    /* always cleanup */
+    curl_easy_cleanup(curl);
+  }
+  return 0;
+}