Week 7: Arrays (2D Arrays) in C

Note: For all questions, you can define M and N using #define directive at the beginning of your program if required.

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Q1. Store Total Salary of N Employees

Question:
Write a program to store the total salary of N employees in an array. For each employee calculate the total salary.

• HRA Allowance: 40% of basic salary
• Special Allowance: 25% of basic salary
• Total Salary: Basic + HRA + Special Allowance

After calculating, sort the array in descending order of total salary.

Program:

#include <stdio.h>

int main() {
    int i, n;
    printf("Enter the total number of employees: ");
    scanf("%d", &n);

    float a[n][3], basicSalary, houseAllowance, allowance, totalSalary;

    for(i = 0; i < n; i++) {
        printf("Enter the basic salary for employee %d: ", i + 1);
        scanf("%f", &basicSalary);

        houseAllowance = basicSalary * 0.4;
        allowance = basicSalary * 0.25;
        totalSalary = basicSalary + houseAllowance + allowance;

        a[i][0] = basicSalary;
        a[i][1] = houseAllowance;
        a[i][2] = totalSalary;
    }

    printf("\nSalaries details of employees:\n");
    for(i = 0; i < n; i++) {
        printf("Employee %d - Basic: %.2f, House Allowance: %.2f, Total Salary: %.2f\n", i + 1, a[i][0], a[i][1], a[i][2]);
    }

    return 0;
}
````

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## Q2. Sum of Each Row & Column of an MxN Matrix

**Question:**
Write a program to find the sum of each row and each column of a MxN matrix.

**Program:**

```c
#include <stdio.h>

int main() {
    int i, j, m, n;

    printf("Enter number of rows and columns: ");
    scanf("%d %d", &m, &n);

    int matrix[m][n];

    printf("Enter elements of the matrix:\n");
    for(i = 0; i < m; i++) {
        for(j = 0; j < n; j++) {
            scanf("%d", &matrix[i][j]);
        }
    }

    printf("Row sums:\n");
    for(i = 0; i < m; i++) {
        int rowSum = 0;
        for(j = 0; j < n; j++) {
            rowSum += matrix[i][j];
        }
        printf("Sum of row %d: %d\n", i + 1, rowSum);
    }

    printf("Column sums:\n");
    for(j = 0; j < n; j++) {
        int colSum = 0;
        for(i = 0; i < m; i++) {
            colSum += matrix[i][j];
        }
        printf("Sum of column %d: %d\n", j + 1, colSum);
    }

    return 0;
}

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Q3. Check if Matrix is Square & Sum of Diagonals

Question: Check if the matrix is square; if not, print Invalid. If it is square, calculate the sum of the main diagonal and opposite diagonal.

Program:

#include <stdio.h>

int main() {
    int i, j, m, n;
    printf("Enter the number of rows and columns: ");
    scanf("%d %d", &m, &n);

    if (m != n) {
        printf("Invalid\n");
        return 0;
    }

    int matrix[m][n];

    printf("Enter elements of the matrix:\n");
    for(i = 0; i < m; i++) {
        for(j = 0; j < n; j++) {
            scanf("%d", &matrix[i][j]);
        }
    }

    int mainDiagonalSum = 0, oppositeDiagonalSum = 0;

    for(i = 0; i < m; i++) {
        mainDiagonalSum += matrix[i][i];
        oppositeDiagonalSum += matrix[i][m - i - 1];
    }

    printf("Main diagonal sum: %d\n", mainDiagonalSum);
    printf("Opposite diagonal sum: %d\n", oppositeDiagonalSum);

    return 0;
}

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Q4. Linear Search in MxN Matrix

Question: Perform linear search in a MxN matrix and print all occurrences of the key element.

Program:

#include <stdio.h>

int main() {
    int i, j, m, n, key, found = 0;

    printf("Enter the number of rows and columns: ");
    scanf("%d %d", &m, &n);

    int matrix[m][n];

    printf("Enter the elements of the matrix:\n");
    for(i = 0; i < m; i++) {
        for(j = 0; j < n; j++) {
            scanf("%d", &matrix[i][j]);
        }
    }

    printf("Enter the key element to search for: ");
    scanf("%d", &key);

    for(i = 0; i < m; i++) {
        for(j = 0; j < n; j++) {
            if(matrix[i][j] == key) {
                printf("Found %d at position (%d, %d)\n", key, i, j);
                found = 1;
            }
        }
    }

    if(!found) {
        printf("Element %d not found in the matrix.\n", key);
    }

    return 0;
}

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