Runtime Libraries
This section details the core runtime libraries provided with the Windows SDK for C++ development. These libraries are essential for the execution and behavior of your applications on Windows.
C++ Runtime Library (MSVCPRT)
The C++ Runtime Library (often referred to as the Standard Library or STL implementation) provides fundamental classes and functions for C++ programming, including:
- Standard template containers (e.g.,
std::vector,std::map) - Algorithms (e.g.,
std::sort,std::find) - I/O streams (e.g.,
std::cout,std::cin) - String manipulation (e.g.,
std::string) - Exception handling
- Memory management
Key headers include:
<vector><string><iostream><algorithm><memory>
Universal CRT (ucrtbase.dll)
The Universal C Runtime provides a standardized C library that is included with Windows. It is the default C runtime for UWP applications and is recommended for desktop applications as well.
It includes standard C library functions and support for features like:
- Standard I/O (
stdio.h) - String manipulation (
string.h) - Math functions (
math.h) - Time functions (
time.h) - Memory allocation (
stdlib.h)
You will typically link against the Universal CRT automatically when using modern Visual Studio C++ toolchains.
Windows Core Runtime Libraries
These libraries are fundamental for interacting with the Windows operating system at a low level. They are often used implicitly by higher-level APIs.
Kernel32.lib / Kernel32.dll
Provides core operating system services, including:
- Process and thread management
- Memory management
- File and I/O operations
- Synchronization primitives
User32.lib / User32.dll
Responsible for the Windows user interface, including:
- Window management
- Message handling
- User input (keyboard, mouse)
- GDI (Graphics Device Interface) functions
GDI32.lib / Gdi32.dll
Provides graphics drawing capabilities, including:
- Drawing lines, shapes, text
- Managing pens, brushes, fonts
- Printer support
Common Runtime Components
A selection of commonly used runtime components and their primary functions:
| Library/DLL | Primary Purpose | Key Functions/APIs |
|---|---|---|
msvcrt.dll |
Older C Runtime (legacy) | printf, malloc, strcpy |
ucrtbase.dll |
Universal C Runtime | printf, malloc, strcpy, fopen |
msvcp140.dll |
C++ Standard Library (VS 2015-2022) | std::vector, std::string, std::cout |
kernel32.dll |
Core OS Services | CreateProcess, ReadFile, CloseHandle |
user32.dll |
User Interface Management | CreateWindow, MessageBox, GetMessage |
gdi32.dll |
Graphics Device Interface | TextOut, Rectangle, CreateFont |
combase.dll |
COM Infrastructure | COM object creation, interfaces |
Linking Considerations
When building your C++ applications, you will need to ensure that the correct runtime libraries are linked. The Visual Studio IDE handles most of this automatically based on your project settings. For manual linking, you'll refer to the .lib files found in your SDK's lib directories.
Be mindful of:
- Static vs. Dynamic Linking: Some runtime components can be statically linked into your executable, while others must be dynamically linked via DLLs.
- Runtime Version Mismatch: Ensure that the C++ runtime DLLs (e.g.,
msvcp140.dll) deployed with your application are compatible with the version used during development.