The problem is in your comparison: if ((-1) < SIZE) sizeof typically returns an unsigned long, so SIZE will be unsigned long, whereas -1 is just an int. The rules for promotion in C and related languages mean that -1 will be converted to size_t before the comparison, so -1 will become a very large … Read more
An enum is guaranteed to be represented by an integer, but the actual type (and its signedness) is implementation-dependent. You can force an enumeration to be represented by a signed type by giving one of the enumerators a negative value: enum SignedEnum { a = -1 }; In C++0x, the underlying type of an enumeration … Read more
It’s all in your things.size() type. It isn’t int, but size_t (it exists in C++, not in C) which equals to some “usual” unsigned type, i.e. unsigned int for x86_32. Operator “less” (<) cannot be applied to two operands of different sign. There’s just no such opcodes, and standard doesn’t specify, whether compiler can make … Read more
No, addresses aren’t always positive – on x86_64, pointers are sign-extended and the address space is clustered symmetrically around 0 (though it is usual for the “negative” addresses to be kernel addresses). However the point is mostly moot, since C only defines the meaning of < and > pointer comparisons between pointers that are to … Read more
One way to think about it is that signed, two’s complement format works by assigning each bit a power of two, then flipping the sign of the last power of two. Let’s look at -4, for example, which is represented as 100. This means that the value is -1 x 2^2 + 0 x 2^1 … Read more
The number itself is always interpreted as a non-negative number. Hexadecimal constants don’t have a sign or any inherent way to express a negative number. The type of the constant is the first one of these which can represent their value: int unsigned int long int unsigned long int long long int unsigned long long … Read more
Because 2147483648 is a long value as it does not fit in an int (in common system with 32-bit int and 64-bit long, on system with 32-bit long it is of type long long). So -2147483648 is of type long, not int. Remember in C, an unsuffixed decimal integer constant is of the first type … Read more
Assuming: You have 2’s-complement representations in mind; and, By (unsigned long) you mean unsigned 32-bit integer, then you just need to add 2**32 (or 1 << 32) to the negative value. For example, apply this to -1: >>> -1 -1 >>> _ + 2**32 4294967295L >>> bin(_) ‘0b11111111111111111111111111111111’ Assumption #1 means you want -1 to … Read more
Because the int value is promoted to an unsigned int. specifically 0xFFFFFFFC on a 32-bit machine, which as an unsigned int is 4294967292, considerably larger than 10 C99 6.3.1.1-p2 If an int can represent all values of the original type (as restricted by the width, for a bit-field), the value is converted to an int; … 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