Telegram Bot C Library

This is a lightweight C library to interact with the Telegram Bot API. It supports basic messaging features like reading updates, sending messages/documents, deleting, and editing messages. It's perfect for minimal bots written in C.

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🛠️ Requirements

Before you begin, make sure you have the following:

• GCC compiler
• libcurl installed
• cJSON installed
• Basic knowledge of C programming
• Telegram Bot Token

You will also need to compile the library as a static .a file (optional for reusability).

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📁 Files

File	Description
tgbot.c	Source file with all bot logic
tgbot.h	Header file for declarations
README.md	This file
last_update.txt	Used for tracking offset

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Setting up the bot

1. Start by Adding Your Bot Token

In tgbot.c, replace the placeholder with your bot’s API token.

char* BOT_API = "YOUR_TELEGRAM_BOT_TOKEN";

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⚙️ Functions

Helper Functions

These are internal utilities to support the main bot functions.

size_t callback(char *ptr, size_t size, size_t nmemb, void *userdata);
void last_up_add();
void last_update_read();
char* latest_file(const char* file_path);

• callback() → Used internally for handling libcurl responses.
• last_up_add() / last_update_read() → Save and load last update offset from last_update.txt.
• latest_file(path) → Returns the latest file from a directory (useful for sending recent downloads).

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Main Bot Functions

updateData *get_updates();
void get_document(char *file_id);
int send_message(long long *CID, const char *message, const int reply, long long reply_id);
void send_document(long long *CID, const char *file_name, const int reply, const int reply_id);
void delete_message(long long *CID, const int bot_msgid, long long *group_chat_id);
void edit_message(long long *CID, const int edit_msg_id, const char *message);

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Receiving Updates

The Update data is actually struct that contain

typedef struct updateData {
    char *chat_Result; // chat message initially "chat"
    long long chat_id; // chat id initially -1
    long long group_chat_id; // group chat id(if it exist) initially -1
    int reply_id;  // reply message id, initially -1
    char *file_id; // file id(if file was sent) initially "file_id=NULL"
} updateData;

You can receiving updates by adding this line at the top of your code

updateData *updateData = get_updates();

and access them as struct

updateData->chat_Result // or this updateData.chat_Result if u prefer "." (dot)

All of the data are

• chat_Result → The user's message
• chat_id → The chat id
• group_chat_id → The group chat id (if any)
• reply_id → The message id to reply to
• file_id → To download a file by using the get_document() function

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Getting Files

When someone sends a file get_updates() function will capture a unique file id with that you can download any files the function get_document() need a file id inorder to download file

void get_document(char *file_id);

start by checking if file id exist and then fetch it-

if(userdata->file_id)
    get_document(userdata->file_id);

Keep in mind that when a file is fetched, it will be saved in its respective folder based on its type. For example, photos will be saved in the Photos folder

Sending Messages

To send a message, use:

int send_message(long long *CID, const char *message, const int reply, long long reply_id);

Parameters:

• CID → Pointer to chat id
• message → Message text to send
• reply → 1 to reply to a message, 0 otherwise
• reply_id → Message id to reply to (from get_updates)

The function returns the bot's sent message id, which can be used to edit or delete the message later.

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Sending Documents

To send files under 50 MB(Telegram Bot limitation):

void send_document(long long *CID, const char *file_name, const int reply, const int reply_id);

Parameters:

• CID → Pointer to chat id
• file_name → Path to file (can include directories)
• reply → 1 to reply, 0 otherwise
• reply_id → Message id to reply to

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Deleting Messages

void delete_message(long long *CID, const int bot_msgid, long long *group_chat_id);

Parameters:

• CID → Pointer to chat id
• bot_msgid → Bot message id (from send_message)
• group_chat_id → Pointer to group chat id (if applicable)

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Editing Messages

void edit_message(long long *CID, const int edit_msg_id, const char *message);

Parameters:

• CID → Pointer to chat id
• edit_msg_id → Bot message id to edit (from send_message)
• message → New message text

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Pull Requests & Contributions

If you'd like to contribute, feel free to fork the repo and submit a pull request.

Before You Start

• Ensure your code follows a clean and readable C coding style.
• Keep functions modular and well-documented using comments.
• Do not include your own bot token or any sensitive data in commits.
• Test your code thoroughly before submitting a pull request.
• Use descriptive function/variable names and meaningful commit messages.

We appreciate your contributions to improve this project!

PRs That Will Be Closed

Pull requests will be closed without merging if they:

• Add unnecessary or unrelated features
• Contain broken, untested, or buggy code
• Include hardcoded sensitive data (e.g., bot tokens)
• Do not follow basic C coding style or formatting guidelines

Please make sure your contributions adhere to the project standards to avoid delays or closures.

Creating Issues

If you encounter bugs, have feature requests, or want to suggest improvements, please open an issue on the repository.

When creating an issue, please include:

• A clear and descriptive title.
• A detailed description of the problem or suggestion.
• Steps to reproduce the bug (if applicable).
• Your environment details (OS, compiler version, etc.).
• Any relevant code snippets or error messages.

This helps us understand and address your issue more efficiently. Thank you for helping improve the project!

📄 License

This project is licensed under the MIT License — see the LICENSE file for details.