Meaning of U suffix

Question

What does the postfix (or suffix) U mean for the following values?

0U
100U

Answer 1

It stands for unsigned.

When you declare a constant, you can also specify its type. Another common example is L, which stands for long. (and you have to put it twice to specify a 64-bit constant).

Example: 1ULL.

It helps in avoiding explicit casts.