Pointers can be passed to functions to modify the original data.

void increment(int *num) {
    (*num)++;
}

int main() {
    int x = 5;
    increment(&x);
    printf("x: %d\n", x); // Output: 6
    return 0;
}

Pointers can be manipulated using arithmetic operations.

int numbers[] = {10, 20, 30, 40, 50};
int *ptr = numbers;

printf("%d\n", *ptr); // Output: 10
ptr++; // Move the pointer to the next element
printf("%d\n", *ptr); // Output: 20

Pointers are variables that store memory addresses.

int num = 10;
int *ptr; // Declare a pointer
ptr = # // Assign the address of num to the pointer

printf("Value of num: %d\n", num); // Output: 10
printf("Address of num: %p\n", &num); // Output: Address in hexadecimal format
printf("Value of ptr: %p\n", ptr); // Output: Address of num

Strings are arrays of characters.
char name[] = "John";
printf("Name: %s\n", name); // Output: John

// String input using scanf()
char city[50];
printf("Enter your city: ");
scanf("%s", city);
printf("City: %s\n", city);

Multi-dimensional arrays are arrays of arrays.

int matrix[3][3] = {
    {1, 2, 3},
    {4, 5, 6},
    {7, 8, 9}
};
printf("%d\n", matrix[1][2]); // Output: 6

Elements in an array can be accessed using their index.

int numbers[5] = {10, 20, 30, 40, 50};
printf("%d\n", numbers[2]); // Output: 30

Arrays are collections of elements of the same data type.

// Declaring an array of integers
int numbers[5];

// Initializing an array with values
int primes[5] = {2, 3, 5, 7, 11};

Variables declared outside any function have global scope and can be accessed throughout the program. Variables declared inside a function have local scope and can only be accessed within that function.

int global_var = 10; // Global variable

void my_function() {
    int local_var = 5; // Local variable
    printf("Global variable: %d\n", global_var);
    printf("Local variable: %d\n", local_var);
}

int main() {
    my_function();
    return 0;
}

Function prototypes provide the compiler with information about the functions before their actual implementation.

// Function prototype
int add_numbers(int a, int b);

int main() {
    int sum = add_numbers(10, 20);
    printf("Sum: %d\n", sum);
    return 0;
}

// Function definition
int add_numbers(int a, int b) {
    return a + b;
}

Functions can take arguments as input and return values as output.

int square(int num) {
    return num * num;
}

int result = square(5);
printf("Result: %d\n", result); // Output: 25