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What is the difference between char s[] and char *s?
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static char __unnamed[] = "abc";
char *c = __unnamed;
Note the implicit cast from char[] to char *, which is always legal.
Then if you modify c[0], you also modify __unnamed, which is UB.
This is documented at 6.4.5 "String literals":
5 In translation phase 7, a byte or code of value zero i...
When should I use mmap for file access?
...he buffers are often properly aligned and do not trap when dereferencing a casted pointer.
You also have to be careful that you do not access outside of the map. It can easily happen if you use string functions on your map, and your file does not contain a \0 at the end. It will work most of the ti...
Position of least significant bit that is set
...her bytes by storing/reloading instead of shifting, because of the pointer-cast. (totally unnecessary BTW, and makes it endian-dependent unlike a shift wouldn't). Anyway, so not only is the microbenchmark unrealistic because of hot cache, it also has the branch predictors primed and tests inputs t...
What's the difference between size_t and int in C++?
...G_PTR is an unsigned long type used for pointer precision. It is used when casting a pointer to a long type to perform pointer arithmetic.
This type is declared as follows:
typedef unsigned __int3264 ULONG_PTR;
share
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Is the “struct hack” technically undefined behavior?
...instead of explicitly adding the offset to the pointer returned by malloc, cast to char *, is irrelevant.
Technically, p->s[0] is the single element of the char array inside the struct, the next few elements (e.g. p->s[1] through p->s[3]) are likely padding bytes inside the struct, which c...
What is Rack middleware?
...mment about it being a way to filter requests probably comes from the RailsCast episode 151: Rack Middleware screen cast.
Rack middleware evolved out of Rack and there is a great intro at Introduction to Rack middleware.
There's an intro to middleware on Wikipedia here.
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How to check if PHP array is associative or sequential?
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@ARW "PHP seems to cast everything to an int in an array definition if it can." - yep, that's exactly what happens. The biggest WTF is that it even does this to floats; if you try var_dump([1.2 => 'foo', 1.5 => 'bar']); you'll discover th...
Is PowerShell ready to replace my Cygwin shell on Windows? [closed]
...t when you want a property, you ask for it - you don't have to parse,guess,cast. I did not understand your point about "what happens when objects don't have compatible methods" - Could you say that another way or give an example of the problem? Thanks.
– Jeffrey Snover - MSFT
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In C#, why is String a reference type that behaves like a value type?
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Not only strings are immutable reference types.
Multi-cast delegates too.
That is why it is safe to write
protected void OnMyEventHandler()
{
delegate handler = this.MyEventHandler;
if (null != handler)
{
handler(this, new EventArgs());
}
}
I suppo...
What exactly do “IB” and “UB” mean?
...by the compiler writers. An example of this is the result of a reinterpret_cast. usually, it simply changes the type of a pointer, without modifying the address, but the mapping is actually implementation-defined, so a compiler could map to a completely different address, as long as it documented th...