Can two-dimensional arrays have different lengths in each row?

Yes, two-dimensional arrays can have different lengths in each row.

In computer science, a two-dimensional array is essentially an array of arrays. The 'outer' array contains 'inner' arrays as its elements. These inner arrays can be of different lengths, creating a 'jagged' array, also known as a ragged array or a list of lists. This is in contrast to a 'rectangular' or 'square' array, where each row has the same number of elements.

In many programming languages, such as Java, C#, and Python, two-dimensional arrays do not have to be rectangular. They can be jagged, meaning that each 'row' (or 'column', depending on how you visualise it) can have a different length. This is because the two-dimensional array is actually an array of references to other arrays. Each of these referenced arrays can be a different length, and they are allocated separately.

For example, in Java, you could create a two-dimensional array with different row lengths like this:

```
int[][] jaggedArray = new int[3][];
jaggedArray[0] = new int[5];
jaggedArray[1] = new int[3];
jaggedArray[2] = new int[7];
```

In this example, `jaggedArray` is a two-dimensional array with three rows. The first row has 5 elements, the second row has 3 elements, and the third row has 7 elements.

However, it's important to note that not all programming languages support jagged arrays. In some languages, such as C and C++, two-dimensional arrays must be rectangular. This is because these languages treat a two-dimensional array as a single block of memory, rather than an array of references to other arrays.

In conclusion, whether or not a two-dimensional array can have different lengths in each row depends on the programming language you are using. If your language supports jagged arrays, then yes, you can have different lengths in each row. If not, then all rows must be the same length.