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Unexpected bitshift behavior in C


Unexpected bitshift behavior in C

By : Jeff
Date : September 23 2020, 07:00 AM
I wish this helpful for you You're performing an illegal bitshift.
Shifting by a value greater or equal than the size in bits of the left operand results in undefined behavior. This is documented in section 6.5.7p3 of the C standard:
code :
int x = 0;
uint32_t mask = 0xFFFFFFFF;
...
if (x == 0) {
    result = 0;
} else {
    result = addr & (mask >> (32 - x));
}


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Unexpected bitshift results

Unexpected bitshift results


By : Lars
Date : March 29 2020, 07:55 AM
seems to work fine a short int has 16, not just 8 bits.
So you will likely to get "0111 1111 1000 0000" as the result from 0xff<<7.
Unwanted Java bitshift behavior

Unwanted Java bitshift behavior


By : Vikas Bihani
Date : March 29 2020, 07:55 AM
help you fix your problem Yes, you're correct; shifts are modded by 32 (or 64, for longs) before they're applied.
JLS 15.19:
ng-options inside ng-repeat (with similar looking object) unexpected behavior, weird behavior

ng-options inside ng-repeat (with similar looking object) unexpected behavior, weird behavior


By : user3073299
Date : March 29 2020, 07:55 AM
it fixes the issue There is a conflict between two item variable
item in ng-repeat. item model in select box
code :
<select 
id="deviceList_{{$index}}"
name="deviceList_name_{{$index}}"
ng-model="item1"                         
....
</select>
<div id="device-options" ng-show="item1.id > -1">
Undefined behavior when constexpr-evaluating negative bitshift?

Undefined behavior when constexpr-evaluating negative bitshift?


By : tkbarry1
Date : March 29 2020, 07:55 AM
I wish did fix the issue. GCC complains because your definition of y is explicitly an ill-formed constexpr declaration. The initialzier violates [expr.const]/2, which specifies:
Is it expected that a too large bitshift is undefined behavior in Rust?

Is it expected that a too large bitshift is undefined behavior in Rust?


By : Mark
Date : March 29 2020, 07:55 AM
This might help you No, this is not expected, but it is not undefined behavior. This is "just" a bug.
There should be no difference between how the constant is computed at compile time and how the value is computed at runtime. This is a hard problem in general as the machine performing the compilation and the machine running the code might have completely different architectures.
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