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author | Max Filippov <jcmvbkbc@gmail.com> | 2015-03-30 10:08:30 +0300 |
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committer | Max Filippov <jcmvbkbc@gmail.com> | 2015-03-30 10:11:05 +0300 |
commit | e267eed62caf49d6d2b0d91c60d30b700d08729f (patch) | |
tree | ed518de7b08c1db91dc3abf899a374ead03d1db4 /c.html.markdown | |
parent | 1f49ae9306cb9ca933827b43d327c85598d58907 (diff) |
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.
Diffstat (limited to 'c.html.markdown')
-rw-r--r-- | c.html.markdown | 4 |
1 files changed, 2 insertions, 2 deletions
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 |