Because integers in computers are generally represented by 2 bytes, that is, 16 bits. The first number represents a symbol, so the smallest negative number can be reached, and the negative number 2 is 15 power. Although the positive part can also have the power of 15, the value 0 accounts for 1, so the largest positive value is the power of 15 minus 1.

In a computer, fixed points are divided into signed numbers and unsigned numbers. Among them, there are three representations of signed number: original code, complement and complement. Inverse code means that the inverse code of a specified positive number is the same as its original code; The negation of a negative number is the bitwise negation of its original code, except the sign bit.

The word length of a computer is n bits, the highest bit of an n-bit binary number is a sign bit, and the rest of the n- 1 bits are numerical bits. When using complement notation, the range of representable number x is -2 power ≤X≤2 power-1.

Extended data:

Size and range of storage space for common data types:

1 and Byte (byte type) are represented by 1 byte, and the numerical range is 0-255.

2.Boolean (Boolean/Logic) is represented by 2 bytes, and the numerical range is true or false.

3.Integer (integer type) is represented by 2 bytes, and the numerical range is-32,768 ~ 32,767.

4.Long (long integer) is represented by 4 bytes, and its numerical range is -2,147,483,648 ~ 2,147,483,647.

5.Single (single-precision floating-point type) is represented by 4 bytes, and the range of values is:

Negative range:-3.402823E38 ~-1.405438+0298e-45.

Positive number range:1.401298e-45 ~ 3.423e38.

6.Double (double-precision floating-point type) is represented by 8 bytes, and the range of values is:

Negative range:-1.797,693,134,862,32e308 ~-4.940,656,458,412,47e-324.

Positive number range: 4.940,656,458,412,47e-324 ~1.797,693,134,862,32e308.

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