原文：http://coolaj86.info/articles/json-c-example.html
So you want to parse JSON with C? Welcome aboard! First get json-c, configure, compile, and update your ld cache
Make JSON-C (libjson)
x86 / Ubuntu
wget http://oss.metaparadigm.com/json-c/json-c-0.9.tar.gz
tar xf json-c-0.9.tar.gz
cd json-c-0.9
./configure && make && sudo make install
sudo ldconfig
ARM / OpenEmbedded
bitbake json-c
Simple Test
Now use one of the test files provided or this example: http://www.jroller.com/RickHigh/entry/json_parsing_with_c_simple
json-example.c:
- #include <stdio.h>
- #include <stdlib.h>
- #include <stddef.h>
- #include <string.h>
- #include <json/json.h>
- int main(int argc, char **argv)
- {
- struct json_object *new_obj;
- int pageCount;
- new_obj = json_tokener_parse("/* more difficult test case */ { "glossary": { "title": "example glossary", "pageCount": 100, "GlossDiv": { "title": "S", "GlossList": [ { "ID": "SGML", "SortAs": "SGML", "GlossTerm": "Standard Generalized Markup Language", "Acronym": "SGML", "Abbrev": "ISO 8879:1986", "GlossDef": "A meta-markup language, used to create markup languages such as DocBook.", "GlossSeeAlso": ["GML", "XML", "markup"] } ] } } }");
- printf("new_obj.to_string()=%s
", json_object_to_json_string(new_obj));
- new_obj = json_object_object_get(new_obj, "glossary");
- printf("new_obj.to_string()=%s
", json_object_to_json_string(new_obj));
- new_obj = json_object_object_get(new_obj, "pageCount");
- pageCount = json_object_get_int(new_obj);
- printf("Page count = %d", pageCount);
- json_object_put(new_obj);
- return 0;
- }
Makefile:
all: static
# if you didn't do `sudo make install` you'll need to add your own paths
# to json.json.h and libjson.so - something like -I/usr/local/include/ -L/usr/local/lib
static:
gcc -static -o json-example-static json-example.c -ljson
./json-example-static
shared:
gcc -o json-example-shared json-example.c -L/usr/local/lib -ljson
./json-example-shared
.PHONY: all static shared
Make json-example
make static
make shared
Hopefully that's enough to get you started. The big thing is that when you compile your own projects, make sure that you include the json library and paths.
Segfaults
If you get a segfault it's most likely that you're accessing a key that doesn't exist.