Does the size of a certain pointer always equal to four?

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No, the size of a pointer depends on the architecture of the computer and the data type it points to. For example, on a 32-bit system, the size of a pointer is 4 bytes, but on a 64-bit system, it is typically 8 bytes. Additionally, the size of a pointer to a different data type can also vary depending on the size of that data type.