C/C++ Programming Questions Not Worth Their Own Thread

The Something Awful Forums > Discussion > Serious Hardware/Software Crap > The Cavern of COBOL > C/C++ Programming Questions Not Worth Their Own Thread

Alan Greenspan: Jun 17, 2001

Entheogen posted:

when i do a left shift, does the left most bit get sent to some carry register? on x86 machines, what would be the name of it?
I guess same would go for the right shift and right most digit.

Assuming the SHL/SAL instructions are used by the compiler (generally a safe bet; but still something I'd put into a unit test), the Carry Flag (CF) contains the last bit that was shifted out of the value.

# ¿ Feb 17, 2008 09:47

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# ¿ May 6, 2024 03:24

Alan Greenspan: Jun 17, 2001

xobofni posted:

Really stupid question here about pointers in C.

This code runs just fine.
code:
int main ()
{
    char a[] = "hello world";
    a[0] = 'b';
    return 0;
}
This code crashes.
code:
int main ()
{
    char *a = "hello world";
    a[0] = 'b';
    return 0;
}
I thought those declarations were exaclty the same, but apparently they are not. What am I missing here?

Click me

# ¿ Mar 11, 2008 21:45

Alan Greenspan: Jun 17, 2001

Does anybody know of a C++ parser framework that can load BNF grammar files and generate a parser for them on the fly?

The situation is the following: I need to be able to parse assembler code of various platforms which I do not know during development (because it's actually our customers who create the grammar files, not me).

Basically I need to be able to do:

> parser.exe -grammar_file=x86.gra -input=some_asm_file.asm

as well as

> parser.exe -grammar_file=weirdo_cpu.gra -input=some_weirdo_asm_file.asm

The BNF grammars in the gra-files will have predefined constants like MNEMONIC, INTEGER_OPERAND, REGISTER_NAME, and so on and only the order of the tokens in each grammar rule changes.

# ¿ Jul 1, 2008 18:23

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