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@@ -94,7 +94,7 @@ make
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make DESTDIR=$pkgdir install
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```
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-CMake supports a lot of different platforms, not only UNIX Makefiles, but only UNIX Makefiles have been tested. It works on GNU/Linux and has been confirmed to compile on some versions of macOS, FreeBSD, Cygwin, Solaris and OpenIndiana.
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+CMake supports a lot of different platforms, not only UNIX Makefiles, but only UNIX Makefiles have been tested. It works on GNU/Linux and has been confirmed to compile on some versions of macOS, Cygwin, Solaris and OpenIndiana.
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#### Makefile
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If you don't have CMake available, but still have make. You can use the makefile to build cJSON:
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@@ -123,7 +123,7 @@ If you want, you can install the compiled library to your system using `make ins
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```
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Assume that you got this from a file, a webserver, or magic JSON elves, whatever,
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-you have a char * to it. Everything is a cJSON struct.
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+you have a `char *` to it. Everything is a `cJSON` struct.
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Get it parsed:
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```c
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@@ -134,20 +134,20 @@ This is an object. We're in C. We don't have objects. But we do have structs.
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What's the framerate?
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```c
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-cJSON * format = cJSON_GetObjectItem(root,"format");
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-int framerate = cJSON_GetObjectItem(format,"frame rate")->valueint;
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+cJSON *format = cJSON_GetObjectItem(root, "format");
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+int framerate = cJSON_GetObjectItem(format, "frame rate")->valueint;
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```
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Want to change the framerate?
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```c
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-cJSON_GetObjectItem(format,"frame rate")->valueint = 25;
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+cJSON_GetObjectItem(format, "frame rate")->valueint = 25;
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```
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Back to disk?
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```c
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-char * rendered = cJSON_Print(root);
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+char *rendered = cJSON_Print(root);
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```
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Finished? Delete the root (this takes care of everything else).
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@@ -160,7 +160,8 @@ That's AUTO mode. If you're going to use Auto mode, you really ought to check po
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before you dereference them. If you want to see how you'd build this struct in code?
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```c
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-cJSON *root,*fmt;
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+cJSON *root;
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+cJSON *fmt;
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root = cJSON_CreateObject();
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cJSON_AddItemToObject(root, "name", cJSON_CreateString("Jack (\"Bee\") Nimble"));
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cJSON_AddItemToObject(root, "format", fmt = cJSON_CreateObject());
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@@ -172,92 +173,113 @@ cJSON_AddNumberToObject(fmt, "frame rate", 24);
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```
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Hopefully we can agree that's not a lot of code? There's no overhead, no unnecessary setup.
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-Look at test.c for a bunch of nice examples, mostly all ripped off the json.org site, and
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+Look at `test.c` for a bunch of nice examples, mostly all ripped off the [json.org](http://json.org) site, and
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a few from elsewhere.
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What about manual mode? First up you need some detail.
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-Let's cover how the cJSON objects represent the JSON data.
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+Let's cover how the `cJSON` objects represent the JSON data.
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cJSON doesn't distinguish arrays from objects in handling; just type.
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-Each cJSON has, potentially, a child, siblings, value, a name.
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+Each `cJSON` has, potentially, a child, siblings, value, a name.
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-The root object has: Object Type and a Child
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-The Child has name "name", with value "Jack ("Bee") Nimble", and a sibling:
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-Sibling has type Object, name "format", and a child.
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-That child has type String, name "type", value "rect", and a sibling:
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-Sibling has type Number, name "width", value 1920, and a sibling:
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-Sibling has type Number, name "height", value 1080, and a sibling:
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-Sibling has type False, name "interlace", and a sibling:
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-Sibling has type Number, name "frame rate", value 24
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+* The `root` object has: *Object* Type and a Child
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+* The Child has name "name", with value "Jack ("Bee") Nimble", and a sibling:
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+* Sibling has type *Object*, name "format", and a child.
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+* That child has type *String*, name "type", value "rect", and a sibling:
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+* Sibling has type *Number*, name "width", value 1920, and a sibling:
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+* Sibling has type *Number*, name "height", value 1080, and a sibling:
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+* Sibling has type *False*, name "interlace", and a sibling:
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+* Sibling has type *Number*, name "frame rate", value 24
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-# Here's the structure:
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+### Here's the structure:
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```c
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typedef struct cJSON {
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- struct cJSON *next,*prev;
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- struct cJSON *child;
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+ struct cJSON *next,*prev;
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+ struct cJSON *child;
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- int type;
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+ int type;
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- char *valuestring;
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- int valueint;
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- double valuedouble;
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+ char *valuestring;
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+ int valueint;
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+ double valuedouble;
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- char *string;
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+ char *string;
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} cJSON;
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```
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By default all values are 0 unless set by virtue of being meaningful.
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-next/prev is a doubly linked list of siblings. next takes you to your sibling,
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-prev takes you back from your sibling to you.
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-Only objects and arrays have a "child", and it's the head of the doubly linked list.
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-A "child" entry will have prev==0, but next potentially points on. The last sibling has next=0.
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-The type expresses Null/True/False/Number/String/Array/Object, all of which are #defined in
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-cJSON.h
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+`next`/`prev` is a doubly linked list of siblings. `next` takes you to your sibling,
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+`prev` takes you back from your sibling to you.
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+Only objects and arrays have a `child`, and it's the head of the doubly linked list.
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+A `child` entry will have `prev == 0`, but next potentially points on. The last sibling has `next == 0`.
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+The type expresses *Null*/*True*/*False*/*Number*/*String*/*Array*/*Object*, all of which are `#defined` in
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+`cJSON.h`.
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-A Number has valueint and valuedouble. If you're expecting an int, read valueint, if not read
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-valuedouble.
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+A *Number* has `valueint` and `valuedouble`. If you're expecting an `int`, read `valueint`, if not read
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+`valuedouble`.
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-Any entry which is in the linked list which is the child of an object will have a "string"
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-which is the "name" of the entry. When I said "name" in the above example, that's "string".
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-"string" is the JSON name for the 'variable name' if you will.
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+Any entry which is in the linked list which is the child of an object will have a `string`
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+which is the "name" of the entry. When I said "name" in the above example, that's `string`.
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+`string` is the JSON name for the 'variable name' if you will.
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Now you can trivially walk the lists, recursively, and parse as you please.
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-You can invoke cJSON_Parse to get cJSON to parse for you, and then you can take
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+You can invoke `cJSON_Parse` to get cJSON to parse for you, and then you can take
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the root object, and traverse the structure (which is, formally, an N-tree),
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and tokenise as you please. If you wanted to build a callback style parser, this is how
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you'd do it (just an example, since these things are very specific):
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```c
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-void parse_and_callback(cJSON *item,const char *prefix)
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+void parse_and_callback(cJSON *item, const char *prefix)
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{
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- while (item)
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- {
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- char *newprefix = malloc(strlen(prefix) + strlen(item->name) + 2);
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- sprintf(newprefix,"%s/%s",prefix,item->name);
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- int dorecurse = callback(newprefix, item->type, item);
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- if (item->child && dorecurse) parse_and_callback(item->child, newprefix);
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- item = item->next;
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- free(newprefix);
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- }
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+ while (item)
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+ {
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+ char *newprefix = malloc(strlen(prefix) + strlen(item->name) + 2);
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+ sprintf(newprefix, "%s/%s", prefix, item->name);
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+ int dorecurse = callback(newprefix, item->type, item);
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+ if (item->child && dorecurse)
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+ {
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+ parse_and_callback(item->child, newprefix);
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+ }
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+ item = item->next;
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+ free(newprefix);
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+ }
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}
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```
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-The prefix process will build you a separated list, to simplify your callback handling.
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-The 'dorecurse' flag would let the callback decide to handle sub-arrays on it's own, or
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+The `prefix` process will build you a separated list, to simplify your callback handling.
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+The `dorecurse` flag would let the callback decide to handle sub-arrays on it's own, or
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let you invoke it per-item. For the item above, your callback might look like this:
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```c
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- int callback(const char *name,int type,cJSON *item)
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+int callback(const char *name, int type, cJSON *item)
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+{
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+ if (!strcmp(name, "name"))
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+ {
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+ /* populate name */
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+ }
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+ else if (!strcmp(name, "format/type")
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+ {
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+ /* handle "rect" */ }
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+ else if (!strcmp(name, "format/width")
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+ {
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+ /* 800 */
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+ }
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+ else if (!strcmp(name, "format/height")
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+ {
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+ /* 600 */
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+ }
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+ else if (!strcmp(name, "format/interlace")
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+ {
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+ /* false */
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+ }
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+ else if (!strcmp(name, "format/frame rate")
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{
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- if (!strcmp(name,"name")) { /* populate name */ }
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- else if (!strcmp(name,"format/type") { /* handle "rect" */ }
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- else if (!strcmp(name,"format/width") { /* 800 */ }
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- else if (!strcmp(name,"format/height") { /* 600 */ }
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- else if (!strcmp(name,"format/interlace") { /* false */ }
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- else if (!strcmp(name,"format/frame rate") { /* 24 */ }
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- return 1;
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+ /* 24 */
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}
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+
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+ return 1;
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+}
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```
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Alternatively, you might like to parse iteratively.
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@@ -266,28 +288,31 @@ You'd use:
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```c
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void parse_object(cJSON *item)
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{
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- int i;
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- for (i = 0 ; i < cJSON_GetArraySize(item) ; i++)
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- {
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- cJSON * subitem = cJSON_GetArrayItem(item, i);
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- // handle subitem
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- }
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+ int i;
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+ for (i = 0; i < cJSON_GetArraySize(item); i++)
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+ {
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+ cJSON *subitem = cJSON_GetArrayItem(item, i);
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+ // handle subitem
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+ }
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}
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```
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Or, for PROPER manual mode:
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```c
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-void parse_object(cJSON * item)
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+void parse_object(cJSON *item)
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{
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- cJSON *subitem = item->child;
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- while (subitem)
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- {
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- // handle subitem
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- if (subitem->child) parse_object(subitem->child);
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-
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- subitem = subitem->next;
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- }
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+ cJSON *subitem = item->child;
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+ while (subitem)
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+ {
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+ // handle subitem
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+ if (subitem->child)
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+ {
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+ parse_object(subitem->child);
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+ }
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+
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+ subitem = subitem->next;
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+ }
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}
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```
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@@ -303,19 +328,29 @@ Also, if you find a use for it, you can manually build the objects.
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For instance, suppose you wanted to build an array of objects?
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```c
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-cJSON * objects[24];
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+cJSON *objects[24];
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-cJSON * Create_array_of_anything(cJSON ** items, int num)
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+cJSON *Create_array_of_anything(cJSON **items, int num)
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{
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- int i;
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- cJSON * prev, * root = cJSON_CreateArray();
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- for (i = 0 ; i < 24 ; i++)
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- {
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- if (!i) root->child = objects[i];
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- else prev->next = objects[i], objects[i]->prev = prev;
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- prev = objects[i];
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- }
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- return root;
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+ int i;
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+ cJSON *prev;
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+ cJSON *root = cJSON_CreateArray();
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+ for (i = 0; i < 24; i++)
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+ {
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+ if (!i)
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+ {
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+ root->child = objects[i];
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+ }
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+ else
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+ {
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+ prev->next = objects[i];
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+ objects[i]->prev = prev;
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+ }
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+
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+ prev = objects[i];
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+ }
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+
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+ return root;
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}
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```
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@@ -325,11 +360,11 @@ cJSON doesn't make any assumptions about what order you create things in.
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You can attach the objects, as above, and later add children to each
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of those objects.
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-As soon as you call cJSON_Print, it renders the structure to text.
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+As soon as you call `cJSON_Print`, it renders the structure to text.
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-The test.c code shows how to handle a bunch of typical cases. If you uncomment
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-the code, it'll load, parse and print a bunch of test files, also from json.org,
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-which are more complex than I'd care to try and stash into a const char array[].
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+The `test.c` code shows how to handle a bunch of typical cases. If you uncomment
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+the code, it'll load, parse and print a bunch of test files, also from [json.org](http://json.org),
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+which are more complex than I'd care to try and stash into a `const char array[]`.
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# Enjoy cJSON!
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