# cstdalign

***

**1. Aligning a Structure to a Specific Boundary**

```cpp
struct MyStruct {
    char c;
    int i;
};

alignas(32) MyStruct myStruct;  // Aligns MyStruct to a 32-byte boundary
```

**2. Ensuring Proper Alignment for Multi-Threaded Access**

```cpp
struct SharedData {
    int count;
    std::mutex mtx;
};

__attribute__((aligned(64))) SharedData sharedData;  // Aligns SharedData to a 64-byte boundary for efficient multi-threaded access
```

**3. Aligning Arrays for Vectorization**

```cpp
int data[16] __attribute__((aligned(16)));  // Aligns the array to a 16-byte boundary for vectorization optimizations
```

**4. Optimizing Cache Performance**

```cpp
struct CacheLineAligned {
    char pad[64];  // Adds 64 bytes of padding to align the following data to a cache line boundary
    int data;
};
```

**5. Aligning Pointers to Structures**

```cpp
struct MyStruct {
    int i;
    char c;
};

MyStruct* ptr = (MyStruct*)__aligned_alloc(32, sizeof(MyStruct));  // Aligns the pointer to a 32-byte boundary
```

**6. Aligning Memory Allocated with malloc()**

```cpp
void* mem = aligned_alloc(64, 256);  // Allocates 256 bytes of memory aligned to a 64-byte boundary
```

**7. Aligning Memory Allocated with new()**

```cpp
class MyClass {
    int i;
    char c;
};

MyClass* obj = new(__attribute__((aligned(32)))) MyClass();  // Aligns the new object to a 32-byte boundary
```

**8. Aligning Return Values**

```cpp
struct MyStruct {
    int i;
    char c;
};

__attribute__((aligned(32))) MyStruct myFunction() {  // Ensures the return value is aligned to a 32-byte boundary
    return {1, 'a'};
}
```

**9. Aligning Class Data Members**

```cpp
class MyClass {
    __attribute__((aligned(32))) int i;  // Aligns the class member i to a 32-byte boundary
    char c;
};
```

**10. Aligning Union Members**

```cpp
union MyUnion {
    int i __attribute__((aligned(16)));  // Aligns the i member to a 16-byte boundary
    char c;
};
```

**11. Aligning Arrays of Structures**

```cpp
struct MyStruct {
    int i;
    char c;
};

MyStruct data[10] __attribute__((aligned(16)));  // Aligns the array of MyStruct to a 16-byte boundary
```

**12. Aligning Pointers to Functions**

```cpp
typedef void (*MyFuncPtrType)() __attribute__((aligned(64)));  // Aligns the function pointer to a 64-byte boundary
```

**13. Aligning Structures in a Union**

```cpp
union MyUnion {
    struct {
        int i __attribute__((aligned(32)));  // Aligns the i member to a 32-byte boundary
        char c;
    };
    double d;
};
```

**14. Aligning Base Class Subobjects**

```cpp
class BaseClass {
    int i;
};

class DerivedClass : public BaseClass {
    __attribute__((aligned(16))) int j;  // Aligns the j member to a 16-byte boundary in the derived class
};
```

**15. Aligning Virtual Base Class Subobjects**

```cpp
class BaseClass {
    virtual int i;
};

class DerivedClass : public virtual BaseClass {
    __attribute__((aligned(32))) int j;  // Aligns the j member to a 32-byte boundary in the derived class
};
```

**16. Aligning Non-POD Structures**

```cpp
struct MyStruct {
    int i;
    MyStruct* next __attribute__((aligned(16)));  // Aligns the next member to a 16-byte boundary
};
```

**17. Aligning Bitfields**

```cpp
struct MyStruct {
    int i : 3;
    char c __attribute__((aligned(4)));  // Aligns the c member to a 4-byte boundary
    int j : 5;
};
```

**18. Aligning Nested Structures**

```cpp
struct NestedStruct {
    int i;
};

struct MyStruct {
    NestedStruct nested __attribute__((aligned(16)));  // Aligns the nested structure to a 16-byte boundary
};
```

**19. Aligning Structures with Explicit Layout**

```cpp
struct MyStruct {
    char c __attribute__((aligned(1)));
    short s __attribute__((aligned(2)));
    int i __attribute__((aligned(4)));
};
```

**20. Aligning Anonymous Structures**

```cpp
struct {
    int i __attribute__((aligned(8)));
} data;  // Aligns the anonymous structure to an 8-byte boundary
```

**21. Aligning Variadic Argument Lists**

```cpp
void myFunction(int n, ...) {
    va_list ap;
    va_start(ap, n);

    // Align each variadic argument to a 8-byte boundary
    int* arg = va_arg(ap, int*), arg2;
    __aligned(8) int arg3 = va_arg(ap, int);
    arg2 = va_arg(ap, int);

    va_end(ap);
}
```

**22. Aligning Structures in C++11**

```cpp
struct __attribute__((aligned(16))) MyStruct {
    int i;
    char c;
};
```

**23. Aligning Arrays in C++11**

```cpp
int data[16] __attribute__((aligned(16)));
```

**24. Aligning Pointers in C++11**

```cpp
MyStruct* ptr __attribute__((aligned(32)));
```

**25. Aligning Structures in C++17**

```cpp
struct alignas(32) MyStruct {
    int i;
    char c;
};
```

**26. Aligning Arrays in C++17**

```cpp
int data[16] alignas(16);
```

**27. Aligning Pointers in C++17**

```cpp
MyStruct* ptr alignas(32);
```

**28. Using the std::align() Function**

```cpp
MyStruct* ptr = (MyStruct*)std::align(64, sizeof(MyStruct));  // Aligns the pointer to a 64-byte boundary
```

**29. Using the std::aligned\_storage Class**

```cpp
std::aligned_storage<sizeof(MyStruct), 64>::type storage;  // Creates 64 bytes of aligned storage for a MyStruct
```

**30. Aligning Homogeneous Aggregates**

```cpp
int arr[10] __attribute__((aligned(16)));  // Aligns an array of ints to a 16-byte boundary
```

**31. Aligning Heterogeneous Aggregates**

```cpp
struct MyStruct {
    int i;
    char c;
} __attribute__((aligned(16)));  // Aligns a heterogeneous aggregate to a 16-byte boundary
```

**32. Aligning Structures with Virtual Functions**

```cpp
struct BaseClass {
    virtual void f();
};

struct DerivedClass : public BaseClass {
    int i __attribute__((aligned(32)));  // Aligns the i member to a 32-byte boundary in the derived class
};
```

**33. Aligning Structures with Multiple Inheritance**

```cpp
struct BaseClass1 {
    int i;
};

struct BaseClass2 {
    int j;
};

struct DerivedClass : public BaseClass1, BaseClass2 {
    int k __attribute__((aligned(16)));  // Aligns the k member to a 16-byte boundary in the derived class
};
```

**34. Aligning Structures with Diamond Inheritance**

```cpp
struct BaseClass {
    int i;
};

struct DerivedClass1 : public BaseClass {
    int j __attribute__((aligned(32)));  // Aligns the j member to a 32-byte boundary in the derived class
};

struct DerivedClass2 : public BaseClass {
    int k __attribute__((aligned(16)));  // Aligns the k member to a 16-byte boundary in the derived class
};

struct DiamondClass : public DerivedClass1, public DerivedClass2 {
    int l;
};
```

**35. Aligning Unions with Heterogeneous Members**

```cpp
union MyUnion {
    int i __attribute__((aligned(32)));  // Aligns the i member to a 32-byte boundary
    double d;
};
```

**36. Aligning Uninitialized Structures**

```cpp
struct MyStruct {
    int i;
    char c;
};

alignas(16) MyStruct uninitializedData;  // Declares an uninitialized MyStruct aligned to a 16-byte boundary
```

**37. Aligning Dynamically Allocated Structures**

```cpp
MyStruct* ptr = (MyStruct*)aligned_alloc(32, sizeof(MyStruct));  // Allocates a MyStruct aligned to a 32-byte boundary
```

**38. Aligning Structures in Shared Memory**

```cpp
struct MyStruct {
    int i;
    char c;
} __attribute__((aligned(32)));  // Aligns MyStruct to a 32-byte boundary for shared memory access
```

**39. Aligning Structures in Embedded Systems**

```cpp
struct MyStruct {
    int i;
    char c;
} __attribute__((aligned(16)));  // Aligns MyStruct to a 16-byte boundary for efficient hardware access
```

**40. Aligning Structures for Real-Time Systems**

```cpp
struct MyStruct {
    int i;
    char c;
} __attribute__((aligned(64)));  // Aligns MyStruct to a 64-byte boundary for real-time performance
```

**41. Aligning Structures for Data Parallelism**

```cpp
struct MyStruct {
    int i;
    char c;
} __attribute__((aligned(32)));  // Aligns MyStruct to a 32-byte boundary for vectorization and multi-threading
```

**42. Aligning Structures for Performance Optimization**

```cpp
struct MyStruct {
    int i;
    char c;
} __attribute__((aligned(16)));  // Aligns MyStruct to a 16-byte boundary for improved cache performance
```

**43. Aligning Structures for Interoperability**

```cpp
struct MyStruct {
    int i;
    char c;
} __attribute__((aligned(32)));  // Aligns MyStruct to a 32-byte boundary for compatibility with other platforms
```

**44. Aligning Structures for Cross-Compilation**

```cpp
struct MyStruct {
    int i;
    char c;
} __attribute__((aligned(16)));  // Aligns MyStruct to a 16-byte boundary for cross-compilation to different target architectures
```

**45. Aligning Structures for Code Portability**

```cpp
struct MyStruct {
    int i;
    char c;
} __attribute__((aligned(32)));  // Aligns MyStruct to a 32-byte boundary for code portability to different platforms
```

**46. Aligning Structures for Optimization**

```cpp
struct MyStruct {
    int i;
    char c;
} __attribute__((aligned(16)));  // Aligns MyStruct to a 16-byte boundary for optimal performance
```

**47. Aligning Structures for Efficiency**

```cpp
struct MyStruct {
    int i;
    char c;
} __attribute__((aligned(32)));  // Aligns MyStruct to a 32-byte boundary for efficiency
```

**48. Aligning Structures for Contiguity**

```cpp
struct MyStruct {
    int i;
    char c;
} __attribute__((aligned(16)));  // Aligns MyStruct to a 16-byte boundary for contiguity
```

**49. Aligning Structures for Coherency**

```cpp
struct MyStruct {
    int i;
    char c;
} __attribute__((aligned(32)));  // Aligns MyStruct to a 32-byte boundary for coherency
```

**50. Aligning Structures for Data Reuse**

```cpp
struct MyStruct {
    int i;
    char c;
} __attribute__((aligned(16)));  // Aligns MyStruct to a 16-byte boundary for data reuse
```