Prob 2 uint32_t uint16_t printf("C printf("C What are OXIO
Computer Networking: A Top-Down Approach (7th Edition)
7th Edition
ISBN:9780133594140
Author:James Kurose, Keith Ross
Publisher:James Kurose, Keith Ross
Chapter1: Computer Networks And The Internet
Section: Chapter Questions
Problem R1RQ: What is the difference between a host and an end system? List several different types of end...
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Question
![### Problem 2:
Assume we have the following code:
```c
uint32_t arr32[] = {0x11220102, 0x33440304, 0x55660506};
uint16_t *ptr16 = (uint16_t *)arr32;
uint8_t *ptr8 = (uint8_t *)ptr32++;
printf("0x%x\n", *(uint16_t *)ptr32);
printf("0x%x\n", (uint8_t)*(ptr16+1));
```
What are the values printed out from the above code?
---
### Explanation:
This code involves pointer manipulation and type casting in C. The array `arr32` is of type `uint32_t`, which means each element is 4 bytes. The `ptr16` and `ptr8` pointers cast this array to `uint16_t` and `uint8_t` types, respectively.
1. **`ptr32++`**: The original pointer to a `uint32_t` is incremented, moving to the next 4-byte block in the array.
2. **First `printf`**: It prints the value at the new location to which `ptr32` points, cast as a `uint16_t` (since the pointer is incremented, it points to the second element, `0x33440304`).
3. **Second `printf`**: It prints the second byte (using the first element of `arr32`), accessed via the `ptr16` pointer.
This test assesses understanding of pointer arithmetic, data representation, and casting in C.
### Output:
The handwritten notes on the side suggest the expected output values:
- `0x102`
- `0x10`](/v2/_next/image?url=https%3A%2F%2Fcontent.bartleby.com%2Fqna-images%2Fquestion%2F047a7e6a-f025-4b5b-ab83-4ffe14f69253%2F3d2becf1-7662-43fa-8a78-d6b26b9177c6%2Fyeo514f_processed.jpeg&w=3840&q=75)
Transcribed Image Text:### Problem 2:
Assume we have the following code:
```c
uint32_t arr32[] = {0x11220102, 0x33440304, 0x55660506};
uint16_t *ptr16 = (uint16_t *)arr32;
uint8_t *ptr8 = (uint8_t *)ptr32++;
printf("0x%x\n", *(uint16_t *)ptr32);
printf("0x%x\n", (uint8_t)*(ptr16+1));
```
What are the values printed out from the above code?
---
### Explanation:
This code involves pointer manipulation and type casting in C. The array `arr32` is of type `uint32_t`, which means each element is 4 bytes. The `ptr16` and `ptr8` pointers cast this array to `uint16_t` and `uint8_t` types, respectively.
1. **`ptr32++`**: The original pointer to a `uint32_t` is incremented, moving to the next 4-byte block in the array.
2. **First `printf`**: It prints the value at the new location to which `ptr32` points, cast as a `uint16_t` (since the pointer is incremented, it points to the second element, `0x33440304`).
3. **Second `printf`**: It prints the second byte (using the first element of `arr32`), accessed via the `ptr16` pointer.
This test assesses understanding of pointer arithmetic, data representation, and casting in C.
### Output:
The handwritten notes on the side suggest the expected output values:
- `0x102`
- `0x10`
Expert Solution
![](/static/compass_v2/shared-icons/check-mark.png)
Step 1: Array Initialization and Pointer Creation:
- uint32_t arr32[] = {0x11220102, 0x33440304, 0x55660506};
an array arr32 containing three 32-bit unsigned integers (uint32_t). The array is initialized with these hexadecimal values: 0x11220102, 0x33440304, and 0x55660506.
- uint32_t *ptr32 = arr32;
Create a pointer ptr32 of type uint32_t* and set it to point to the first element of the arr32 array. This means ptr32 points to the first 32-bit value, 0x11220102.
- uint16_t *ptr16 = (uint16_t *)arr32;
Create another pointer ptr16 of type uint16_t*. You initialize it by casting the arr32 array to a pointer of uint16_t. This means ptr16 points to the same memory location as arr32, but it interprets the data as 16-bit values.
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