Using the "sizeof" operator on the column of an array in C

Question

Sorry for the newbie question, I am still learning.

Let's say that I have matrix[x][y]

Using sizeof(matrix) will return me the whole size of the array.

Using sizeof(matrix[a]) will return me the size of a certain row.

Using sizeof(matrix[a][b]) will return me the size of what is located in [a][b].

Is there a way to just find the size of a column? If there is not, why? Am I overlooking something? Thanks for your time.

EDIT: Thanks for the help, if someone else is looking for the answer the user "nnn" wrote the following:

For the number of elements in a column:

sizeof(matrix) / sizeof(matrix[a])

For the size in bytes occupied by a column:

sizeof(matrix) / sizeof(matrix[a]) * sizeof(matrix[a][b])

Also "Weather Vane" explains how sizeof works:

sizeof finds the extent of contiguous byte usage in memory, so it can't be used directly to find the amount of memory used by each column. The array, a row, or an element: yes. A column: no

Answer 1

For the number of elements in a column, divide matrix size by row size:

sizeof(matrix) / sizeof(matrix[a])   

For the size in bytes occupied by a column (the actual answer for the question), multiply number of elements (previous expression) by element size:

sizeof(matrix) / sizeof(matrix[a]) * sizeof(matrix[a][b])

Even if this can't be achieved by using a single sizeof operator, the sizeof is evaluated at compile time, and usually the compiler will substitute these arithmetic operations with the actual result, so there will be no runtime performance degradation caused by this.

Also, the usage of a and b in the expression above can be replaced by 0, i.e. matrix[0] and matrix[0][0], because all the elements have the same size.