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This article mainly explains how to install and use leveldb. Interested friends may wish to have a look at it. The method introduced in this paper is simple, fast and practical. Let's let the editor take you to learn how to install and use leveldb.

Brief introduction of leveldb installation and use of leveldb

Leveldb is a fast key-value pair storage database developed by Google with C++, providing sequential mapping from string keys to string values.

Leveldb installation downloads leveldbgit clone https://github.com/google/leveldb.git compiling leveldbcd leveldb/make

The compiled dynamic libraries and static libraries are respectively under out-shared,out-static:

Ls leveldb/out-shared/libleveldb.so.1.20ls leveldb/out-static/libleveldb.an install leveldb

Only dynamic libraries need to be installed, and static libraries can be linked directly when you compile

# cp leveldb header filesudo cp-r / leveldb/include/ / usr/include/# cp lib to / usr/lib/sudo cp / leveldb/out-shared/libleveldb.so.1.20 / usr/lib/# create linksudo ln-s / usr/lib/libleveldb.so.1.20 / usr/lib/libleveldb.so.1sudo ln-s / usr/lib/libleveldb.so.1.20 / usr/lib/libleveldb.so# update lib cachesudo ldconfig

Check to see if the installation is successful

Ls / usr/lib/libleveldb.so*# shows that the following three files are installed successfully / used by usr/lib/libleveldb.so.1.20/usr/lib/libleveldb.so.1/usr/lib/libleveldb.soleveldb

Let's write a hello_leveldb.cc to test our leveldb.

# include

# include

# include

# include

/ / include the necessary header files

# include

Using namespace std

Int main (void) {leveldb::DB * db = nullptr; leveldb::Options options; / / create the database options.create_if_missing = true; / / if the database does not exist in / tmp/testdb leveldb::Status status = leveldb::DB::Open (options, "/ tmp/testdb", & db); assert (status.ok ()); std::string key = "A" Std::string value = "a"; std::string get_value; / / write key1-> value1 leveldb::Status s = db- > Put (leveldb::WriteOptions (), key, value); / / read the value corresponding to key:people if the write is successful

If (s.ok ()) s = db- > Get (leveldb::ReadOptions (), "A", & get_value)

/ / output if (s.ok ()) if it is read successfully

Cout

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