Why Does `(-2147483648 > 0)` Evaluate to True in Some C Implementations?

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Why Does (-2147483648 > 0) Return True in C ?

In C , -2147483648 is interpreted as a positive literal value (2147483648) with a unary minus operator. However, if the positive literal overflows the int range on your platform, the compiler's behavior becomes undefined.

In practice, undefined behavior may result in various interpretations. Some implementations might represent the value as a negative number that becomes positive after applying unary minus, while others might use unsigned types to represent it.

To avoid this ambiguity, constants like INT_MIN are typically defined as

#define INT_MIN (-2147483647 - 1)

instead of

#define INT_MIN -2147483648

This ensures that INT_MIN represents the correct negative value intended.

When the expression is cast to int, as in

if (int(-2147483648) > 0)

the compiler evaluates the expression as a negative number in the domain of int, resulting in a false output.

It's important to note that undefined behavior varies between compilers and platforms. To ensure predictable results, it's always recommended to use explicitly defined constants and avoid borderline values that may lead to implementation-specific behavior.

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