Formula to determine the range of signed and unsigned data types C++

Question

I\'m just starting out in C++ (literally my second day) and I\'ve been assigned to calculate the ranges of the varying data types, signed and unsigned. The problem is, the way m

Answer 1

std::numeric_limits

You can get the actual values of these limits using these functions:

• T std::numeric_limits::min()
• T std::numeric_limits::max()

You substitute the appropriate type in place of T, such as signed char or unsigned char.

Formulas

The formulas for a signed number with N bits (using two's complement) are

• min = -1 * 2^{N - 1}
• max = 2^{N - 1} - 1

The formulas for an unsigned number with N bits are

• min = 0
• max = 2^N - 1

Example: 8-bit char

The char has N = 8 bits. Let's verify these formulas with signed char and unsigned char.

• signed char
  • min = -1 * 2^{N - 1} = -1 * 2⁷ = -128
  • max = 2^{N - 1} - 1 = 2⁷ - 1 = 127
• unsigned char
  • min = 0
  • max = 2^N - 1 = 2⁸ - 1 = 255