Test: 2D Arrays - EmSAT Achieve MCQ

A 2D array is an array of arrays, where each element in the array is itself an array. It represents a table or matrix-like structure.

In C++, the syntax for declaring a 2D array is 'int array[][]'; or 'int array[rowSize][colSize]';, where 'rowSize' and 'colSize' are the desired sizes of the array.

To access an element in a 2D array, we use the syntax 'array[row][column]', where 'row' and 'column' are the indices of the desired element.

To initialize a 2D array with values in C++, we use the syntax 'int array[][] = {{1, 2, 3}, {4, 5, 6}};', where each inner array represents a row and the values inside the inner arrays represent the elements of each row.

C++ does not impose a maximum limit on the number of dimensions an array can have. However, the practical limit depends on the available memory and the capabilities of the compiler.

To pass a 2D array to a function in C++, you can pass the entire array as a single argument. The function signature would look like 'void functionName(int array[][colSize])'.

In C++, you can perform addition and subtraction operations on 2D arrays by applying the respective operations to each corresponding element in the arrays.

The time complexity of accessing an element in a 2D array by its index is constant, O(1), as the index directly determines the memory location of the element.

In C++, there is no direct way to find the number of rows in a 2D array. You need to keep track of the row size separately or use a row size constant if the size is fixed.

In C++, elements in a 2D array are stored in a row-major order, meaning that the elements of each row are stored in a contiguous block of memory.

The code initializes a 2D array 'arr' with values. The expression 'arr[1][2]' accesses the element at row 1 and column 2, which is 6. The output will be 6.

The code initializes a 2D array 'arr' with values. The expression 'arr[1][1] + arr[0][0]' adds the values at row 1, column 1 (which is 4) and row 0, column 0 (which is 1). The result is 5, and the output will be 5.

The code initializes a 2D array 'arr' with values. The expression 'arr[1][2] - arr[0][1]' subtracts the value at row 0, column 1 (which is 2) from the value at row 1, column 2 (which is 6). The result is 4, and the output will be 4.

The code initializes a 2D array 'arr' with values. The expression 'arr[2][1] * arr[0][2]' multiplies the value at row 2, column 1 (which is 8) with the value at row 0, column 2 (which is 3). The result is 24, and the output will be 24.

The code initializes a 2D array 'arr' with values. The expression 'arr[2][0] / arr[1][1]' divides the value at row 2, column 0 (which is 7) by the value at row 1, column 1 (which is 5). The result is 1, and the output will be 1.

The code initializes a 2D array 'arr' with values. The expression '*(arr[1] + 2)' accesses the element at index 2 in the second row (row index 1). This is equivalent to 'arr[1][2]', which is 6. The output will be 6.

The code initializes a 2D array 'arr' with values. The expression '*(*(arr + 2) + 1)' accesses the element at row 2 (row index 2) and column 1 (column index 1). This is equivalent to 'arr[2][1]', which is 6. The output will be 6.

The code subtracts 'arr[0]' (which is a pointer to the first row) from 'arr[1]' (which is a pointer to the second row). Subtracting two pointers of the same type is not allowed in C++, so it results in a compilation error.

The code uses the 'sizeof' operator to calculate the total size of the 2D array 'arr'. The expression 'sizeof(arr)' returns the total size of the array in bytes. By dividing it by the size of each row ('sizeof(arr[0])'), we get the number of rows. In this case, 'sizeof(arr) / sizeof(arr[0]') is equivalent to '6 / 4', which is 2. The output will be 2.

The code uses the 'sizeof' operator to calculate the size of 'arr[0]', which represents the first row of the 2D array 'arr'. The expression 'sizeof(arr[0])' returns the size of the first row in bytes. By dividing it by the size of an 'int' (sizeof(int)), we get the number of elements in the row. In this case, 'sizeof(arr[0]) / sizeof(int)' is equivalent to '12 / 4', which is 3. The output will be 3.