Two Dimensional Array In C Mcq Exercise 3

• ✅ 4 rows, 3 columns
• ✅ 4 columns, 3 rows
• ✅ None of the above

Explanation:

The correct answer is option "b". A declaration int arr4;, where "arr" is an array with 4 rows and 3 columns, represents a two-dimensional array in C programming. The array's four sub-arrays, each with three integer elements, are indicated by this. As a consequence, it sets up the data into a structure with four rows and three columns that looks like a grid. This structure makes effective access to and manipulation of data in a tabular format possible.

1. How the elements are stored in a two-dimensional array in C?

• ✅ Column-major order
• ✅ Diagonal order
• ✅ Random order
• ✅ Row-major order

Explanation:

The correct answer is option "d". A two-dimensional array in C is stored with its elements in row-major order. By storing each row sequentially, the array's elements are stored in a single and continuous block of memory. An instance of this would be a 2D array int arr3, where the elements are stored in order as follows: arr0, arr0, arr0, arr1, arr1, arr1, arr2, arr2, arr2. This method ensures that each element in a single row is near every other element in memory to improve cache speed and row-by-row access efficiency. Row-major order is different from column-major order, which stores all of a column's elements together.

1. In what way can a two-dimensional character array be initialized?

• ✅ char arr2 = {{'a'}, {'b', 'c', 'd'}};
• ✅ char arr2 = {'a', 'b', 'c', 'd'};
• ✅ char arr2 = {{'a', 'b'}, {'c', 'd'}};
• ✅ Both b and c

Explanation:

The correct answer is option "d". In C, each of these methods may be used to initialize a two-dimensional array of characters. The char arr2 = {{'a', 'b'}, {'c', 'd'}}; explicitly defines each row's elements using nested brackets. The char arr2 = {'a', 'b', 'c', 'd'}; fills every element of the array in row-major order and initializes it in a flat and linear manner. Both approaches result in the same final array structure, with 'a' and 'b' in the first row and 'c' and 'd' in the second.

1. How is a pointer to a two-dimensional array declared?

• ✅ int ptr ;
• ✅ int ptrN;
• ✅ int **ptr;
• ✅ int (*ptr)[N];

Explanation:

The correct answer is option "d". A two-dimensional array can be declared using the syntax int (*ptr)[N];, which informs us that the parameter ptr refers to an array of N numbers, where N is the array's number of columns. It is particularly helpful when working with dynamically allocated two-dimensional arrays or when passing a two-dimensional array to a function.

1. How can we find the number of rows in a two-dimensional array (arr)?

• ✅ sizeof(arr) / sizeof(arr0)
• ✅ sizeof(arr[0]) / sizeof(arr0)
• ✅ sizeof(arr)
• ✅ sizeof(arr) / sizeof(arr[0])

Explanation:

The correct answer is option "d". The sizeof(arr) / sizeof(arr[0]) is an expression in C that may be used to determine the number of rows in a two-dimensional array arr. The array's entire size in bytes is provided by sizeof(arr). The array's first row's size in bytes is provided by sizeof(arr[0]). The number of rows in the array may be found by dividing the array's entire size by the size of a single row (sizeof(arr[0])). It is a simple approach that uses the fact that, regardless of the array's dimensions, the number of available rows can be calculated by dividing the array's overall size by the size of a single row.

1. How can we determine how many columns there are in a two-dimensional array arr?

• ✅ sizeof(arr[0]) / sizeof(arr0)
• ✅ sizeof(arr[0]) / sizeof(arr0)
• ✅ sizeof(arr) / sizeof(arr[0])
• ✅ sizeof(arr) / sizeof(arr0)

Explanation:

The accurate choice is alternative "a". Employ the expression "sizeof(arr[0]) / sizeof(arr0)" to ascertain the number of columns present in a 2D array arr in the C programming language.

The function "sizeof(arr[0])" returns the total size in bytes of the first row of the array, which is applicable to all columns within that row. To ascertain the size of an individual element within the array in bytes, the function "sizeof(arr0)" can be used, aiding in understanding the proportional sizes of each element.

When we divide the size of the first row (sizeof(arr[0])) by the size of a single element (sizeof(arr0)), we can determine the number of columns in the array. This method allows us to calculate how many elements can be accommodated within a specific row by dividing the total byte size of the row by the byte size of each individual element.