People (and especially beginners) should never use scanf(“%s”) or gets() or any other functions that do not have buffer overflow protection, unless you know for certain that the input will always be of a specific format (and perhaps not even then). Remember than scanf stands for “scan formatted” and there’s precious little less formatted than user-entered data. It’s ideal if you have total control of … Read more
What may cause this difference? Basically, the memory allocator allocates pages of memory at once for use by programs, and it gives you a pointer within them (making sure the following space is free for use). Since these pages are usually bigger than 8KiB, you have no issue in your mini-program. But if a larger program is … Read more
OP’s sample code is incorrect. Endian conversion works at the bit and 8-bit byte level. Most endian issues deal with the byte level. OP code is doing a endian change at the 4-bit nibble level. Recommend instead: If performance is truly important, the particular processor would need to be known. Otherwise, leave it to the … Read more
The behavior of stack (growing up or growing down) depends on the application binary interface (ABI) and how the call stack (aka activation record) is organized. Throughout its lifetime a program is bound to communicate with other programs like OS. ABI determines how a program can communicate with another program. The stack for different architectures … Read more
It depends on what you mean by “empty”. If you just want a zero-length string, then your example will work. This will also work: If you want to zero the entire contents of the string, you can do it this way: but this will only work for zeroing up to the first NULL character. If … Read more
It looks like you’re confused by the double stars in The double stars just means that this function expects you to pass a pointer to a pointer to a char. This syntax doesn’t include any information about the fact that you are using an array, or that the char is actually the first char of many … Read more
EXC_I386_GPFLT is surely referring to “General Protection fault”, which is the x86’s way to tell you that “you did something that you are not allowed to do”. It typically DOESN’T mean that you access out of memory bounds, but it could be that your code is going out of bounds and causing bad code/data to … Read more
Knuth’s multiplicative method: In general, you should pick a multiplier that is in the order of your hash size (2^32 in the example) and has no common factors with it. This way the hash function covers all your hash space uniformly. Edit: The biggest disadvantage of this hash function is that it preserves divisibility, so if … Read more
Literals that start with 0x are hexadecimal integers. (base 16) The number 0x6400 is 25600. For an example including letters (also used in hexadecimal notation where A = 10, B = 11 … F = 15) The number 0x6BF0 is 27632.
Arrays are indexed from 0, so the loops should be for(i = 0; i<9; i++) and not for(i = 1; i<10; i++) In your case, you probably override part of the stack, but in general, going out of boundaries results in undefined behavior.