iskm/learnxinyminutes-docs
1
0
Fork 0
mirror of https://github.com/adambard/learnxinyminutes-docs.git synced 2024-12-23 09:41:36 +00:00
Code Issues Actions Packages Projects Releases Wiki Activity

c.html: fix #1021 (bitwise negation and shifting into the sign bit)

Browse Source 
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.
This commit is contained in:
Max Filippov 2015-03-30 10:08:30 +03:00
parent 1f49ae9306
commit e267eed62c
1 changed files with 2 additions and 2 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

4
c.html.markdown
View File

@ -234,7 +234,7 @@ int main() {
// same with j-- and --j // same with j-- and --j
// Bitwise operators! // 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; // => 0x00 (bitwise AND)
0x0F | 0xF0; // => 0xFF (bitwise OR) 0x0F | 0xF0; // => 0xFF (bitwise OR)
0x04 ^ 0x0F; // => 0x0B (bitwise XOR) 0x04 ^ 0x0F; // => 0x0B (bitwise XOR)
@ -242,7 +242,7 @@ int main() {
0x02 >> 1; // => 0x01 (bitwise right shift (by 1)) 0x02 >> 1; // => 0x01 (bitwise right shift (by 1))
// Be careful when shifting signed integers - the following are undefined: // 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) // - left-shifting a negative number (int a = -1 << 2)
// - shifting by an offset which is >= the width of the type of the LHS: // - 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 // int a = 1 << 32; // UB if int is 32 bits wide