Comment by Alex Lop. on memcpy and string literal. does it check and consider...
@pmg why not? It will do exactly what it suppose to do. Was your account hacked? strncpy was not designed to work with strings???
View ArticleComment by Alex Lop. on Why are const qualified variables accepted as...
Does this answer your question? Why "initializer element is not a constant" is... not working anymore?
View ArticleComment by Alex Lop. on No output produce after running the code. Blank and...
"otherwise, you would be getting a segmentation fault." - using uninitialized pointer would lead to undefined behavior. Segmentation fault is only one of the possibilities but anything can happen,...
View ArticleComment by Alex Lop. on Include functions from other cpp(hpp) file with main()
Looks like you need additional shared.cpp and shared.hpp files which will declare and define shared function to be used in (other) various compilation object.
View ArticleComment by Alex Lop. on C structure: fields copy order
@Jabberwocky yeah, most likely you are right... but maybe there is some trick that we are not aware of... "no such thing" is also a possible answer to this question but I would like it to be based on...
View ArticleComment by Alex Lop. on C11 - omitting potentially infinite loop by the compiler
@KamilCuk A synchronization operation on one or more memory locations is either an acquire operation, a release operation, both an acquire and release operation, or a consume operation. - I couldn't...
View ArticleComment by Alex Lop. on Merge two bitmask with conflict resolving, with some...
Can you explain how you combine target from a and b? I am not sure I could follow your explanation.
View ArticleComment by Alex Lop. on Transfer from one array to another
what did you try to do so far?
View ArticleComment by Alex Lop. on Find the vulnerability in the C program
When and how does this code run? Can the attacker manipulate (change) the value to which name is pointing asynchronously?
View ArticleComment by Alex Lop. on c while turning void type to string getting weird...
You realize that currently word1 and word2 get a pointer to pointer of type void, right?
View ArticleAnswer by Alex Lop. for Compiler optimization of strcmp I don't understand,...
The compiler inlined strcmp against a known-length string using repe cmpsb which implements memcmp.It loads into register esi the address of the constant literal string "LETMEWIN\n". Note that the...
View ArticleAnswer by Alex Lop. for Comparing a bit to a boolean
You can create a mask based on doSet value:#define AMAZING_FLAG_IDX 1#define AMAZING_FLAG (1u << AMAZING_FLAG_IDX)...uint16_t set_mask = doSet << AMAZING_FLAG_IDX;Now your check can look...
View ArticleAnswer by Alex Lop. for Can someone explain to me why my factorial recursion...
factorial(i) = (factorial(i - 1) * i);This line is invalid in terms of C standard. It is related to the lvalue and rvalue definition.lvalue - is an expression referring to an object.The name 'lvalue'...
View ArticleAnswer by Alex Lop. for How can I get GCC to optimize this bit-shifting...
In addition to Booboo's answer, you can try the following which answers your questionHow can I get GCC to optimize this into a move?Just cast each shifted bit-field expression to unsigned shortunsigned...
View ArticleAnswer by Alex Lop. for How to link two global variables to same address...
This doesn't directly answers your question but I would suggest defining a geter function in provider.h:const int *getConfigProvider(void);and in provider.cconst int *getConfigProvider(void){ static...
View ArticleAnswer by Alex Lop. for How to split string in c?
str_1 and str_2 are arrays of char and the way you fill in the data is fine. But when you are using puts() method, you have to mark the end of the string by '\0' character as described in this link...
View ArticleAnswer by Alex Lop. for Program to print all the bits of one byte union...
Maybe the point of this task is to use arithmetic operations instead of the bitwise ones?Here is an example:void printByteBits(unsigned char num){ const static int div[8] = {1, 2, 4, 8, 16, 32, 64,...
View ArticleAnswer by Alex Lop. for Why is /=2 different from >>=1 for signed integers,...
Dividing a negative integer by 2 is not the same as shifting it to the right by 1.For example -7 / 2 = -3With shifts:11111001b >> 1 = 11111100b which is -4Thus the compiler has to take care of...
View ArticleAnswer by Alex Lop. for MSVC const correctness : spurious C4090 warning
You can disable this warning right before the line which invokes it and restore it back afterwards https://godbolt.org/z/W-XR-Q:#include <string.h>void dummy(void){ int i[42]; int *pi[42]; const...
View ArticleAnswer by Alex Lop. for How do I fix an error in a header file typedef struct...
typedef struct __attribute__((__packed__)) _bitmapThis is the way to define a struct definition without zero paddings in GCC.To prevent zero padding in MVSC, use #pragma pack:#pragma...
View ArticleAnswer by Alex Lop. for When int a[3] has been defined, is there any...
Both b and c point to the same memory but the difference is big:These are two different types (pointer to int and pointer to an array of 3 ints)b is dereferenced to a single integer pointed by b while...
View ArticleAnswer by Alex Lop. for recurrent decent expression parser yeilding a zsh:...
If you enable compiler warnings, you will see that you pass pointer to pointer to struct Node when calling for parse_atom():parse_atom(expr, &Root);while it accepts only a pointer to struct Node...
View ArticleAnswer by Alex Lop. for CODEVITA "similar char" how to reduce my time...
Current execution complexity is O(lq) while l is the length of the input array and q is the number of queries.The complexity of each query is O(l).With proper data structure, you can store the input...
View ArticleAnswer by Alex Lop. for How to check function return value in an if statement...
You can save the return value in a local variable and use it all the way:int check_rc_val = check_length(chars);if (check_rc_val == X){ return check_rc_val;}int check_rc_val = check_rc(chars);if...
View ArticleAnswer by Alex Lop. for for loop: make increment and accessing in one loop
A for loop consists of 4 parts:InitialisationConditionBody codeActionExample: for (initialisation; condition; action) { Body code }The execution order is as I enumerated it above.In your example,for...
View ArticleAnswer by Alex Lop. for Free memory in a loop regardless of return code
It is OK to use such pattern (with goto) in cases when resource management is required and there is a set of checks to be performed while each failure requires to stop the flow and perform the required...
View ArticleAnswer by Alex Lop. for C - calculate address of pointer
I can explain how to calculate the address with few assumptions:The size of int is 4 bytesThe system is little-endianThere are no 0 paddings in the structThus the locals memory layout is so that the...
View ArticleAnswer by Alex Lop. for Is there a better way to mask bits?
For your specific example you can use:if ((bits != 12 && bits != 16) || addressSize != 32) { isValid = false; printf("Invalid!");} else { offsetMask = (1u << bits) - 1;}However it depends...
View ArticleIs pointer arithmetic still well defined after casting with alignment violation?
I know that the result of pointer casting with alignment violation invokes undefined behaviour once dereferenced.But what about pointer casting for address calculation only (without dereferencing)?void...
View ArticleAnswer by Alex Lop. for Trying to confirm XOR's mathematical property
I don't think there is a name for such property. It implies from other properties of the Exclusive Or (see Exclusive Or wiki for more details).Here is the proof:If a^b = c, then a^c = a^(a^b) = <by...
View ArticleAnswer by Alex Lop. for Which kind of signed integer division corresponds to...
In case arithmetic shift right is performed, floor by power of 2 is the best suitable operation which matches signed integer shift right (rounding toward -inf).Note that shift right of signed integer...
View ArticleAnswer by Alex Lop. for What will be the output of the given code below?
You can split this code into something longer but probably more readable like this:#include<stdio.h>int main(){ int a=0, b=1, c=2; int *ptr; if (a + 1 == 1) { // this will be true ptr = &b; }...
View ArticleAnswer by Alex Lop. for Output ',' between number fibonaci in c program
The easiest way is to add additional printf for the ", " string under the condition that it is not the last for loop iteration #include<stdio.h> int main() { int x, y = 0, z = 1, r, i;...
View ArticleAnswer by Alex Lop. for static variable changing value with no error displayed?
printf signature isint printf ( const char * format, ... );The first parameter is the format string and all the following parameters are the format specifiers (subsequences beginning with %).printf("%d...
View ArticleAnswer by Alex Lop. for The behavior of the for loop split between switch cases
default is just a label (address to where the code jumps if n is not -1 or 0).Thus when n is not -1 or 0, the flow enters the body of the for loop skipping the initialisation of j. You can write the...
View ArticleAnswer by Alex Lop. for clang behaves differently with global variables
I understand that extern is the default storage-class specifier for objects defined at file scopeThat's true but the linkage breaks because of "redefinition" of the gv symbol, isn't it?That's because...
View ArticleComment by Alex Lop. on Compiler Optimizations
@Paroz This is very much dependent on the CPU architecture for which the compiler optimizes the code. You can just google for some C "tips and tricks", performing for loops which count down to 0 is...
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