From e267eed62caf49d6d2b0d91c60d30b700d08729f Mon Sep 17 00:00:00 2001 From: Max Filippov Date: Mon, 30 Mar 2015 10:08:30 +0300 Subject: c.html: fix #1021 (bitwise negation and shifting into the sign bit) 0x0f is of type int, for 32-bit int the result is 0xfffffff0. 31'st bit is the sign bit of a 32-bit wide int. --- c.html.markdown | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) (limited to 'c.html.markdown') diff --git a/c.html.markdown b/c.html.markdown index 1696d28f..d3f20eda 100644 --- a/c.html.markdown +++ b/c.html.markdown @@ -234,7 +234,7 @@ int main() { // same with j-- and --j // Bitwise operators! - ~0x0F; // => 0xF0 (bitwise negation, "1's complement") + ~0x0F; // => 0xFFFFFFF0 (bitwise negation, "1's complement", example result for 32-bit int) 0x0F & 0xF0; // => 0x00 (bitwise AND) 0x0F | 0xF0; // => 0xFF (bitwise OR) 0x04 ^ 0x0F; // => 0x0B (bitwise XOR) @@ -242,7 +242,7 @@ int main() { 0x02 >> 1; // => 0x01 (bitwise right shift (by 1)) // Be careful when shifting signed integers - the following are undefined: - // - shifting into the sign bit of a signed integer (int a = 1 << 32) + // - shifting into the sign bit of a signed integer (int a = 1 << 31) // - left-shifting a negative number (int a = -1 << 2) // - shifting by an offset which is >= the width of the type of the LHS: // int a = 1 << 32; // UB if int is 32 bits wide -- cgit v1.2.3