The sizeof operator returns a value of type size_t, which is an unsigned integer type representing the size in bytes of its operand (a type or expression). This value indicates how much memory the operand occupies. The exact size of size_t can vary but is guaranteed to be an unsigned integral type large enough to represent the size of any object in memory

. Key points about the value returned by sizeof:

• It is an unsigned integer type called size_t.
• It represents the number of bytes occupied by the operand.
• The operand can be a data type or an expression.
• The value is determined at compile time.
• On most platforms, size_t corresponds to unsigned int or unsigned long depending on architecture.
• When printing this value in C, the %zu or %lu format specifier is typically used because it is unsigned

In summary, the type of value returned by sizeof is size_t, an unsigned integer representing the size in bytes of the operand.