curl_slist_append.md (1705B)
1 --- 2 c: Copyright (C) Daniel Stenberg, <daniel@haxx.se>, et al. 3 SPDX-License-Identifier: curl 4 Title: curl_slist_append 5 Section: 3 6 Source: libcurl 7 See-also: 8 - curl_slist_free_all (3) 9 Protocol: 10 - All 11 Added-in: 7.1 12 --- 13 14 # NAME 15 16 curl_slist_append - add a string to an slist 17 18 # SYNOPSIS 19 20 ~~~c 21 #include <curl/curl.h> 22 23 struct curl_slist *curl_slist_append(struct curl_slist *list, 24 const char *string); 25 ~~~ 26 27 # DESCRIPTION 28 29 curl_slist_append(3) appends a string to a linked list of strings. The 30 existing **list** should be passed as the first argument and the new list is 31 returned from this function. Pass in NULL in the **list** argument to create 32 a new list. The specified **string** has been appended when this function 33 returns. curl_slist_append(3) copies the string. 34 35 The list should be freed again (after usage) with 36 curl_slist_free_all(3). 37 38 # %PROTOCOLS% 39 40 # EXAMPLE 41 42 ~~~c 43 int main(void) 44 { 45 CURL *handle = curl_easy_init(); 46 struct curl_slist *slist = NULL; 47 struct curl_slist *temp = NULL; 48 49 slist = curl_slist_append(slist, "pragma:"); 50 51 if(!slist) 52 return -1; 53 54 temp = curl_slist_append(slist, "Accept:"); 55 56 if(!temp) { 57 curl_slist_free_all(slist); 58 return -1; 59 } 60 61 slist = temp; 62 63 curl_easy_setopt(handle, CURLOPT_HTTPHEADER, slist); 64 65 curl_easy_perform(handle); 66 67 curl_slist_free_all(slist); /* free the list again */ 68 } 69 ~~~ 70 71 # %AVAILABILITY% 72 73 # RETURN VALUE 74 75 A null pointer is returned if anything went wrong, otherwise the new list 76 pointer is returned. To avoid overwriting an existing non-empty list on 77 failure, the new list should be returned to a temporary variable which can 78 be tested for NULL before updating the original list pointer.