Home
QNX Software Development Platform
QNX SDP is a cross-compiling and debugging environment, including an IDE and command-line tools, for building binary images and programs for target boards running the QNX OS 8.0.
Utilities & Libraries
QNX Helpers Developer's Guide
These libraries provide QNX helpers, including helpers that assist with logging, string conversion, and number and type sizes.
log.h
QNX helpers related to logging.
Macros
These macros are the preferred method for making log calls. They are simplified versions of the QNX helpers logging functions.
QH_LOG_CHECK()
A macro that checks whether a message with the specified severity would be logged

QNX Momentics IDE User's Guide
This User's Guide describes version 8.0 of the Integrated Development Environment (IDE) that's part of the QNX Tool Suite.
QNX Software Development Platform
QNX SDP is a cross-compiling and debugging environment, including an IDE and command-line tools, for building binary images and programs for target boards running the QNX OS 8.0.
- Quickstart Guide
- System Architecture
  The System Architecture guide accompanies the QNX OS and is intended for both application developers and end-users.
- OS Components & Operations
- Graphics
- Programming
- System Security Guide
  The QNX System Security Guide is intended for both system integrators who are responsible for the security of a QNX OS system and developers who want to create a QNX OS resource manager free from vulnerabilities.
- Utilities & Libraries
  - C Library Reference
  - Devctl and Ioctl Commands
  - JSON Library Reference
  - PAM Reference
  - QNX Helpers Developer's Guide
    These libraries provide QNX helpers, including helpers that assist with logging, string conversion, and number and type sizes.
    - attr.h
      QNX helpers - Attribute helpers.
    - endian.h
      QNX helpers - Endianness-related helpers.
    - error.h
      QNX helpers - Helpers related to the errno variable.
    - io.h
      QNX helpers - IO helpers.
    - log.h
      QNX helpers related to logging.
      - Setting up QNX helpers logging
        QNX helpers logging provides default settings and configuration that initialize slog2.
      - Controlling QNX helpers logging
        Logging using QNX helpers is controlled by a configuration string that specifies a combination of the destination flags, the verbosity of a context, and the message-specific flags.
      - Macros
        These macros are the preferred method for making log calls. They are simplified versions of the QNX helpers logging functions.
        qh_log()
        A macro that logs a message along with the originating filename and line number
        QH_LOG_CHECK()
        A macro that checks whether a message with the specified severity would be logged
        QH_LOG_DEFAULT_CONTEXT_INIT()
        A macro that initializes the context whose name is defined by QH_LOG_USER_CONTEXT_NAME
        qh_log_linetrace()
        A macro that logs a debug line trace message along with the originating filename, function, and line number, using the QH_LOG_SEVERITY_DEBUG2 severity level
        qh_log_loc()
        A macro that logs a message along with the originating filename, function, and line number
        qh_log_noloc()
        A macro that logs a message without any associated location information
      - Macro variables
        These macro definitions are used with QNX helpers logging macros and functions.
      - qh_log_check()
        Check whether a message with the given log information structure is logged
      - qh_log_context_create()
        Create a logging context
      - qh_log_context_destroy()
        Destroys a logging context
      - qh_log_context_normalize_name()
        Normalize a context name
      - qh_log_context_t
        The opaque context type used by QNX helpers logging functions
      - qh_log_ex()
        Log a formatted message
      - qh_log_get_destinations()
        Get the destinations a specified context uses
      - qh_log_get_destinations_by_name()
        Get logging destinations based on a context name
      - qh_log_get_verbosity()
        Get the verbosity for the specified combination of context and destinations
      - qh_log_get_verbosity_by_name()
        Get the verbosity for the specified combination of named context and destinations
      - qh_log_info_t
        The information structure used with QNX helpers logging functions
      - qh_log_set_cl_mode()
        Set the logging configuration to command line mode
      - qh_log_update_config()
        Update the logging configuration based on a configuration string
      - qh_log_verbosity_to_str()
        Get the string representation of the specified verbosity
      - qh_vlog_ex()
        Log a formatted message using a variable-argument list
    - misc.h
      QNX helpers - Miscellaneous helpers.
    - qh.h
      QNX helpers that set QH_FILENAME.
    - size.h
      QNX helpers - Size-related helpers.
    - string.h
      QNX helpers - Helpers related to strings and string conversions.
    - time.h
      QNX helpers - Helpers related to time.
  - SPI Framework Technote
  - QNX Cryptography Library
    The QNX Cryptography Library (qcrypto) is a flexible cryptography framework that allows you to choose which cryptography provider responds to requests on a per-process basis.
  - QNX devcrypto Service
  - Utilities Reference
  - WPA Control Interface Reference
    This document provides a reference for the Wi-Fi Protected Access (WPA) control interface, which provides a C API for the WPA/IEEE 802.11i protocols in Wi-Fi client stations. Application developers who want to control WPA operations and get associated status and event data should read this reference.
- Migrating to QNX OS 8.0
QNX Software in the Cloud
QNX Software in the Cloud enables developers to use the QNX OS in the Amazon cloud environment.
QNX Toolkit for Visual Studio Code
This User's Guide describes the QNX^® Toolkit for Visual Studio Code. The guide introduces you to the QNX Toolkit by explaining the QNX development environment and how to build, run, and debug your QNX^® Operating System (OS) applications and systems.
QNX Hypervisor User's Guide
This User's Guide explains the QNX hypervisor architecture and provides instructions for installing and running a QNX Hypervisor system, changing system components and configuration, and using hypervisor features such as virtual devices (vdevs).
Typographical Conventions, Support, and Licensing
This section describes the typographical conventions used throughout the documentation, explains how to obtain technical support, and provides some information about licensing.

QH_LOG_CHECK()

QNX SDP8.0QNX Helpers Developer's GuideAPIDeveloper

A macro that checks whether a message with the specified severity would be logged

Synopsis:

#include <qh/log.h>

#define QH_LOG_CHECK(severity)

Arguments:

severity: The QH_LOG_SEVERITY_* severity level for this log message. Optionally, can be combined with QH_LOG_DEST_*, QH_LOG_NO_DEST_*, or both when specific messages also need to add or block destinations.

Library:

Description:

Given a message's severity, this function determines if it is logged when it is used in a logging call. It is simpler to use than qh_log_check() because it only requires a severity parameter. This function is useful when a message is expensive to build because the caller can determine whether to build a message based on whether it would be logged.

Returns:

Returns true if the message would be logged, and false otherwise.

Page updated: August 11, 2025