4 1. [Overview and Build Status](#overview)
5 2. [Building on Unix](#buildunix)
6 3. [Install Prerequisites](#installprereq)
7 4. [Building with partial threading support](#buildthreaded)
8 5. [Linking to libjson-c](#linking)
9 6. [Using json-c](#using)
11 JSON-C - A JSON implementation in C <a name="overview"></a>
12 -----------------------------------
15 * [AppVeyor Build](https://ci.appveyor.com/project/hawicz/json-c) ![AppVeyor Build Status](https://ci.appveyor.com/api/projects/status/github/json-c/json-c?branch=master&svg=true)
16 * [Travis Build](https://travis-ci.org/json-c/json-c) ![Travis Build Status](https://travis-ci.org/json-c/json-c.svg?branch=master)
18 JSON-C implements a reference counting object model that allows you to easily
19 construct JSON objects in C, output them as JSON formatted strings and parse
20 JSON formatted strings back into the C representation of JSON objects.
21 It aims to conform to [RFC 7159](https://tools.ietf.org/html/rfc7159).
24 Building on Unix with `git`, `gcc` and `autotools` <a name="buildunix"></a>
25 --------------------------------------------------
27 Home page for json-c: https://github.com/json-c/json-c/wiki
31 See also the "Installing prerequisites" section below.
33 - `gcc`, `clang`, or another C compiler
36 If you're not using a release tarball, you'll also need:
38 - `autoconf>=2.64` (`autoreconf`)
41 Make sure you have a complete `libtool` install, including `libtoolize`.
43 To generate docs (e.g. as part of make distcheck) you'll also need:
46 ### Build instructions:
48 `json-c` GitHub repo: https://github.com/json-c/json-c
51 $ git clone https://github.com/json-c/json-c.git
59 $ ./configure # --enable-threading
64 To build and run the test programs:
68 $ make USE_VALGRIND=0 check # optionally skip using valgrind
71 Install prerequisites <a name="installprereq"></a>
72 -----------------------
74 If you are on a relatively modern system, you'll likely be able to install
75 the prerequisites using your OS's packaging system.
77 ### Install using apt (e.g. Ubuntu 16.04.2 LTS)
80 sudo apt install autoconf automake libtool
81 sudo apt install valgrind # optional
84 Then start from the "git clone" command, above.
86 ### Manually install and build autoconf, automake and libtool
88 For older OS's that don't have up-to-date version of the packages will
89 require a bit more work. For example, CentOS release 5.11, etc...
92 curl -O http://ftp.gnu.org/gnu/autoconf/autoconf-2.69.tar.gz
93 curl -O http://ftp.gnu.org/gnu/automake/automake-1.15.tar.gz
94 curl -O http://ftp.gnu.org/gnu/libtool/libtool-2.2.6b.tar.gz
96 tar xzf autoconf-2.69.tar.gz
97 tar xzf automake-1.15.tar.gz
98 tar xzf libtool-2.2.6b.tar.gz
100 export PATH=${HOME}/ac_install/bin:$PATH
102 (cd autoconf-2.69 && \
103 ./configure --prefix ${HOME}/ac_install && \
107 (cd automake-1.15 && \
108 ./configure --prefix ${HOME}/ac_install && \
112 (cd libtool-2.2.6b && \
113 ./configure --prefix ${HOME}/ac_install && \
119 Building with partial threading support <a name="buildthreaded"></a>
120 ----------------------------------------
122 Although json-c does not support fully multi-threaded access to
123 object trees, it has some code to help make use in threaded programs
124 a bit safer. Currently, this is limited to using atomic operations for
125 json_object_get() and json_object_put().
127 Since this may have a performance impact, of at least 3x slower
128 according to https://stackoverflow.com/a/11609063, it is disabled by
129 default. You may turn it on by adjusting your configure command with:
132 Separately, the default hash function used for object field keys,
133 lh_char_hash, uses a compare-and-swap operation to ensure the randomly
134 seed is only generated once. Because this is a one-time operation, it
135 is always compiled in when the compare-and-swap operation is available.
138 Linking to `libjson-c` <a name="linking">
139 ----------------------
141 If your system has `pkgconfig`,
142 then you can just add this to your `makefile`:
145 CFLAGS += $(shell pkg-config --cflags json-c)
146 LDFLAGS += $(shell pkg-config --libs json-c)
149 Without `pkgconfig`, you would do something like this:
152 JSON_C_DIR=/path/to/json_c/install
153 CFLAGS += -I$(JSON_C_DIR)/include/json-c
154 LDFLAGS+= -L$(JSON_C_DIR)/lib -ljson-c
158 Using json-c <a name="using">
161 To use json-c you can either include json.h, or preferrably, one of the
162 following more specific header files:
164 * json_object.h - Core types and methods.
165 * json_tokener.h - Methods for parsing and serializing json-c object trees.
166 * json_pointer.h - JSON Pointer (RFC 6901) implementation for retrieving
167 objects from a json-c object tree.
168 * json_object_iterator.h - Methods for iterating over single json_object instances.
169 * json_visit.h - Methods for walking a tree of json-c objects.
170 * json_util.h - Miscelleanous utility functions.
172 For a full list of headers see [files.html](files.html)