PPS_9_1D and 2D Arrays.pptx

Introduction to Arrays

Lecturer: Pratidnya S. Hegde Patil, Assistant Professor-IT

What is an Array?

An array is a collection of elements of the same data type, referenced by a common name.
It is considered an aggregate or derived data type compared to basic data types (int, float, char).
All elements of an array occupy contiguous memory locations.

Declaration of Arrays

Basic Declaration Example:

Without arrays:

int studMark0, studMark1, studMark2, ..., studMark999;

With arrays:
```
int studMark[1000];
```

This reserves 1000 contiguous memory locations for storing student marks.
Simplifies declaration and manipulation of data.

One Dimensional Arrays

Declaration Format

The declaration of a one-dimensional array follows this syntax:
```
array_element_data_type array_name[array_size];
```

Example Declarations

Examples of one-dimensional array declarations:
- int xNum[20], yNum[50];
- float fPrice[10], fYield;
- char chLetter[70]; (for strings, does not count null terminator)

Array Initialization

Can be initialized at declaration:
- Example: int idNum[7] = {1, 2, 3, 4, 5, 6, 7};
For strings: char chVowel[6] = {'a', 'e', 'i', 'o', 'u', '\0'};
- Each character requires a null terminator.
Compact declaration:
- char chVowel[6] = "aeiou";
- Automatically adds null terminator.

Contiguous Memory and Size Calculation

For 2D arrays, total size is calculated using the formula:
- First index x second index (e.g., Name[6][10] = 60)
3D arrays follow the same principle.

Program Examples

Example 1: Sum of Array Elements

void main() {
    int arr[40], i, n;
    cout<< "Enter total number of numbers ";
    cin>>n;
    cout<< "Enter the elements ";
    for(i=0;i<n;i++) cin>>arr[i];
    for(i=0,sum=0;i<n;i++) sum+=arr[i];
    cout<< "Sum of " << n << " numbers is = " << sum << endl;
    cout<< "Average is " << (float)sum/n << endl;
}

Example 2: Find Smallest Value in Array

Example 3: Find Largest Value

Example 4: Reverse an Array

void main() {
    int my_arr[40], i, n;
    cout<< "Enter total number of numbers ";
    cin>>n;
    cout<< "Enter the elements ";
    for(i=0;i<n;i++) cin>>my_arr[i];
    cout<< "Printing the reverse of the array…\n";
    for(i=n-1;i>=0;i--) cout<< "\t" << my_arr[i];
}

Example 5: Storing and Reading a String

One word:

void main() {
    char str[40];
    cout << "Enter a word ";
    cin >> str;
    cout << "Printing string: " << str << endl;
}

Multiple words: using a loop to read until a newline.

Example 6: Input and Read Array Content and Index

Example 7: Assigning and Printing 2D Array Content

void main() {
    int i, j, arr[3][4] = {1,2,3,4,5,6,7,8,9,10,11,12};
    for(i=0; i<3; i++) {
        for(j=0; j<4; j++)
            cout << "intArray[" << i << "][" << j << "] = " << arr[i][j];
        cout << "\n";
    }
}

Example 8: Swapping Indexes in a 2D Array

Example 9: Reading Strings in Rows

Conclusion

Arrays are a powerful tool for managing related data of the same type, simplifying both data manipulation and organization in programming.