Redis client for C++: connection, installation, and examples

Redis client for C++: complete guide to working with hiredis

Redis is a popular in-memory database used for caching, session management, message queues, and much more. To interact with Redis from C++ applications, there are several libraries, but the most common and reliable is hiredis. This minimalistic, fast, and stable library provides a clean C API that integrates easily into C++ projects. In this article, we will thoroughly cover how to install hiredis, connect it to a project, perform basic Redis operations, and handle possible errors.

What is hiredis?

hiredis is the official C client for Redis, developed by the same team as Redis itself. It supports:

• Synchronous and asynchronous connections
• Automatic reconnection on connection loss
• Command pipelining
• Working with binary data
• Full support for the Redis protocol (RESP2 and RESP3)

Although hiredis is written in C, it is perfectly suited for C++ projects: it can be wrapped in RAII classes, used with modern C++11/17 idioms, and easily combined with other libraries.

Installing hiredis

The easiest way to install it is via the system package manager. Examples for different OS:

Ubuntu / Debian

sudo apt updatesudo apt install libhiredis-dev

macOS (Homebrew)

brew install hiredis

Windows (vcpkg)

vcpkg install hiredis

If you prefer to build hiredis from source (for example, for a custom configuration):

git clone https://github.com/redis/hiredis.gitcd hiredismakesudo make install

Connecting to a Redis server

After installing hiredis, you can connect it to your C++ project. Make sure the compiler settings include the paths to the header files and libraries:

• -I/usr/include (or the path to hiredis.h)
• -lhiredis for linking

Example of minimal code for connecting to Redis running on localhost:6379:

#include <hiredis/hiredis.h>#include <iostream>

int main() {    // Connect to Redis    redisContext *c = redisConnect("127.0.0.1", 6379);    if (c == nullptr || c->err) {        if (c) {            std::cerr << "Connection error: " << c->errstr << std::endl;            redisFree(c);        } else {            std::cerr << "Failed to allocate memory for context" << std::endl;        }        return 1;    }    std::cout << "Connection to Redis established!" << std::endl;

    // Free resources    redisFree(c);    return 0;}

Sending commands and receiving responses

hiredis provides the redisCommand function for sending commands. It returns a pointer to redisReply, which contains the result of the execution. Always check that the reply is not nullptr, and free the memory after use.

Let's look at basic operations: setting and getting a string value.

#include <hiredis/hiredis.h>#include <iostream>#include <string>

int main() {    redisContext *c = redisConnect("127.0.0.1", 6379);    if (!c || c->err) {        std::cerr << "Connection error: " << (c ? c->errstr : "null") << std::endl;        return 1;    }

    // Set the key "myname" with the value "C++ Developer"    redisReply *reply = (redisReply*)redisCommand(c, "SET myname 'C++ Developer'");    if (reply == nullptr) {        std::cerr << "Error executing SET command" << std::endl;        redisFree(c);        return