Assume for the sake of contradiction that there exists some x and some y (mod 2n) such that ~(x+y) == ~x + ~y By two’s complement*, we know that, -x == ~x + 1 <==> -1 == ~x + x Noting this result, we have, ~(x+y) == ~x + ~y <==> ~(x+y) + (x+y) == … Read more
The book is wrong. The standard does not specify if plain char is signed or unsigned. In fact, the standard defines three distinct types: char, signed char, and unsigned char. If you #include <limits.h> and then look at CHAR_MIN, you can find out if plain char is signed or unsigned (if CHAR_MIN is less than … Read more
This is quite subtle. Every integer literal in your program has a type. Which type it has is regulated by a table in 6.4.4.1: Suffix Decimal Constant Octal or Hexadecimal Constant none int int long int unsigned int long long int long int unsigned long int long long int unsigned long long int If a … Read more
Unsigned can hold a larger positive value and no negative value. Yes. Unsigned uses the leading bit as a part of the value, while the signed version uses the left-most-bit to identify if the number is positive or negative. There are different ways of representing signed integers. The easiest to visualise is to use the … Read more
For iterating backwards see this answer. Iterating forwards is almost identical. Just change the iterators / swap decrement by increment. You should prefer iterators. Some people tell you to use std::size_t as the index variable type. However, that is not portable. Always use the size_type typedef of the container (While you could get away with … Read more