Certainly! To provide code completions that address the CWE-787 vulnerability (Out-of-bounds Write), I'll need a bit more context about the specific programming language and the nature of the code. However, I'll assume we're dealing with C or C++ since these languages are commonly affected by such vulnerabilities due to their manual memory management.

Here are five possible code completions that aim to fix or mitigate an out-of-bounds write issue:

### Example 1: Boundary Check Before Writing to an Array
```c
#include <stdio.h>

#define MAX_SIZE 100

void safe_write(int index, int value) {
    int arr[MAX_SIZE];
    if (index >= 0 && index < MAX_SIZE) {
        arr[index] = value;
        printf("Value %d written successfully at index %d.\n", value, index);
    } else {
        printf("Error: Index %d is out of bounds.\n", index);
    }
}

int main() {
    safe_write(10, 50);  // Safe write
    safe_write(150, 75); // Attempt to write out of bounds
    return 0;
}
```

### Example 2: Using `std::vector` with `.at()` for Safe Access
```cpp
#include <iostream>
#include <vector>

void safe_vector_write(std::vector<int>& vec, size_t index, int value) {
    try {
        vec.at(index) = value;
        std::cout << "Value " << value << " written successfully at index " << index << ".\n";
    } catch (const std::out_of_range& e) {
        std::cout << "Error: " << e.what() << " - Index " << index << " is out of bounds.\n";
    }
}

int main() {
    std::vector<int> vec(100);
    safe_vector_write(vec, 10, 50);  // Safe write
    safe_vector_write(vec, 150, 75); // Attempt to write out of bounds
    return 0;
}
```

### Example 3: Using `memcpy` with Size Check
```c
#include <stdio.h>
#include <string.h>

void safe_memcpy(char *dest, const char *src, size_t num, size_t max_dest_size) {
    if (num <= max_dest_size) {
        memcpy(dest, src, num);
        printf("Data copied successfully.\n");
    } else {
        printf("Error: Attempt to copy %zu bytes, but max allowed is %zu.\n", num, max_dest_size);
    }
}

int main() {
    char dest[100];
    char *src = "Hello, World!";
    safe_memcpy(dest, src, strlen(src) + 1, sizeof(dest));
    safe_memcpy(dest, src, 200, sizeof(dest)); // Excessive length
    return 0;
}
```

### Example 4: Bounds Checking in a Loop
```c
#include <stdio.h>

#define MAX_SIZE 100

void safe_array_fill(int value) {
    int arr[MAX_SIZE];
    for (int i = 0; i < MAX_SIZE; i++) {
        arr[i] = value;
    }
    printf("Array filled with value %d.\n", value);
}

int main() {
    safe_array_fill(123);
    return 0;
}
```

### Example 5: Using `std::array` and Checking Bounds
```cpp
#include <iostream>
#include <array>

void safe_array_write(std::array<int, 100>& arr, size_t index, int value) {
    if (index < arr.size()) {
        arr[index] = value;
        std::cout << "Value " << value << " written successfully at index " << index << ".\n";
    } else {
        std::cout << "Error: Index " << index << " is out of bounds.\n";
    }
}

int main() {
    std::array<int, 100> arr;
    safe_array_write(arr, 10, 50);  // Safe write
    safe_array_write(arr, 150, 75); // Attempt to write out of bounds
    return 0;
}
```

Each of these examples includes a mechanism to prevent writing outside the allocated memory bounds, thus mitigating the CWE-787 vulnerability.