C Programming: Arrays, Structs, and Pointers Explained

1. Defining a Car Structure in C

Define a structure suitable for the following details of a car: Brand, Category (compact, family), Model, Engine Size, and Year.

Answer:

struct Datos_auto {
  char brand[30];
  char model[10];
  char category[30];
  int year;
  int size;
};

4. Array Index Out of Bounds

What happens if you assign a value to an element of an array whose index exceeds the array size?

Answer: It will overwrite data in adjacent memory locations.

5. Array Name Representation

If an array is declared as int list[12];, what does the word list represent?

Answer: It represents the array name (which also acts as a pointer to the first element).

6. Definition of a String in C

In the C language, what is a string?

Answer: A string is a composite data type, specifically an array of characters terminated by a null character ('\0').

7. Accessing String Subsets

Assuming the statement char str[] = "Montenegro";, what code would write the last 5 letters ("negro") to standard output?

Answer:

int i;
for (i = 5; i <= 9; i++) {
  printf("%c", str[i]);
}

8. Understanding Pointers

What is a pointer?

Answer: A pointer is the address of a variable. It is a variable like any other that contains a memory address pointing to another location in memory where data is stored.

9. Benefits of Using Pointers

Mention two good reasons for using pointers.

Answer:

• It makes it easy to manipulate arrays.
• It allows for efficient memory management.

10. Referencing Array Elements

Assuming a declaration of an array with 10 elements named table, state two ways to refer to the third element.

Answer: table[2] or *(table + 2).

11. 2D Array and Pointer Notation

Given static int arr[2][3] = {{10, 11, 12}, {13, 14, 15}};, provide a reference to the element 14 using array notation and pointer notation.

Answer:

• Array notation: arr[1][1]
• Pointer notation: *(*(arr + 1) + 1)

12. Function to Swap Two Integers

Write the code for a function to swap two variables of type int.

Answer: Assuming v1 and v2 are declared as global variables:

void swap() {
  int temp;
  temp = v1;
  v1 = v2;
  v2 = temp;
}

13. Summing Array Elements with Pointers

Given static float list[] = {1.0, 2.0, 3.0, 4.0, 5.0};, enter the code to determine the sum using pointers.

Answer:

float sum;
float list[] = {1.0, 2.0, 3.0, 4.0, 5.0};
sum = *(list + 0) + *(list + 1) + *(list + 2) + *(list + 3) + *(list + 4);