779 questions
-1
votes
0
answers
144
views
What is the "#pragma" directive in C++? [duplicate]
I was reading and came across the #pragma directive, so I decided to do some research. However, I didn't understand much and would like to see if someone can shortly explain it to me about the #pragma ...
0
votes
1
answer
109
views
How do I tell gcc to shut up about forward declaring struct inside parameter list?
#pragma GCC diagnostic push
#pragma GCC diagnostic ignore ???
int fstat(int handle, struct stat *statbuf);
/* to get struct stat, #include <asm/stat.h> */
#pragma GCC diagnostic pop
I've ...
- 43.1k
-3
votes
0
answers
40
views
What is and use of pragma function in C [duplicate]
In C while doing file handling what is the use of pragma function. what if i don't use it?
I was trying to make a problem set of harvard cs50 when i came across this. it needs to access bit file byte ...
0
votes
2
answers
71
views
Is the C preprocessor part of the C standard?
I just know that #pragma once is not part of the C standard but rather part of the preprocessor.
In that case, does that make the preprocessor not part of the C standard?
So, are the C programming ...
0
votes
1
answer
35
views
`pragma solidity` is giving error, even though I added the latest version
// SPDX-License-Identifier: MIT
pragma solidity ^0.8.0;
contract BankAccount {
uint private balance;
// Deposit function: adds an amount to the balance
function deposit(uint amount) ...
0
votes
0
answers
23
views
What is the best way to implement file cacheing by different types?
The index page of website I'm working on sends 136 HTTP requests of which 105 are images, which I would like to have cached. The page currently has the meta tags cache-control no-cache and pragma no-...
0
votes
0
answers
55
views
#pragma fenv_access (on) & #pragma STDC FENV_ACCESS ON
For the two pragmas
#pragma fenv_access (on)
#pragma STDC FENV_ACCESS ON
Does it matter I put them before of after #include headers?
Looks to me both are fine?
Why GCC does not support "#pragma ...
- 1
0
votes
1
answer
33
views
clang compiler struct packing - always padded to 2bytes
clang compiler struct packing - always padded to 2bytes
Short: I'm unable to get my clang compiler to pack the packed_struct_test test struct in lwip to 5 bytes. It always shows 6bytes.
Details:
Here'...
- 618
1
vote
1
answer
86
views
Test value of #pragma
In Xcode, I want to find out the value of the STDC FP_CONTRACT pragma after including just float.h and math.h. To my surprise, I couldn't find any way to do it!
So the question: Am I just missing ...
- 52.5k
1
vote
0
answers
169
views
Setting GCC target options (AVX2) for static inline variables with a pragma doesn't work?
I'm using AVX2 instruction to initialize static inline variables in my code. But the following does not compile.
#pragma GCC target("avx2")
#include <iostream>
#include <immintrin.h&...
2
votes
0
answers
97
views
In macro #define can we use #pragma push_macro and pop_macro
My goal is to remove name from SECTION_STOP in the following macros:
// Start creates the object
#define SECTION_START(name, ...) \
auto section_##name = create_section_name(#name, ## __VA_ARGS__);
...
- 143
-2
votes
2
answers
375
views
What does #pragma message do?
Using GCC on Linux (Mint)
I have a line of code ...
#pragma message "blah blah blah"
When I run GCC I get this output with no warning, errors, etc ...
src/source_file.c:29:9: note: ‘#...
- 19.9k
0
votes
1
answer
237
views
Disable XAML binding warning? #pragma warning disable XC0022
I am working w/ Maui XAML, but I would like to disable this XAML warning on a single file (ok maybe a few ;)).
XamlC XC0022 warning : Binding could be compiled if x:DataType is specified.
In C# I ...
- 22.3k
2
votes
2
answers
107
views
How to spawn a single thread with OpenMP (like a std::thread()) and use "#pragma omp single" and "#pragma omp for" afterwards?
I would simply like to spawn a background thread, like std::thread, but just with OpenMP.
Is this possible?
If yes, how ist it done?
To better explain what I want to achieve, here the C++ Code of what ...
- 75
0
votes
0
answers
77
views
Borland C specify symbol name in function declaration
If I declare an external function in a C source file compiled with bcc32.exe (Borland C++ compiler, tested with the free version 5.5.1), it prepends an _ in the .obj file, for example,
extern int ...
- 87k
0
votes
0
answers
119
views
Should I use #pragma once directive in a hpp header, knowing well it contains some definitions? [duplicate]
I know there is use case scenario for '#pragma once' in classic .h headers containing only declarations. But I wonder: what about .hpp files which most of the time contain many definitions. Should I ...
- 61
0
votes
1
answer
106
views
omp library c++ pragma for
I have this code, but I need help to use OpenMP #pragmas to increase its speed. I want to parallelize the for loops over variables i and j. The values of n and m can be much larger, too. For example,...
3
votes
1
answer
117
views
Cpp20 non-strict char*
I've migrated our Visual Studio C++ project to Cpp20, and it's compiling fine except at a couple of places where some non-compliant library is called. The library defines macros like this:
#define ...
- 2,262
0
votes
2
answers
62
views
attribution of anonymous members during constant structure initialisation
Assume the following simple structure in C:
struct entry {
int id;
const char *name;
};
Nothing special. Say I'd like to initialise an array of members globally. One would do:
const static ...
- 1,242
0
votes
1
answer
180
views
What is the equivalent in GCC to MSVC's '#pragma message'?
On MSVC I can issue compilation-time message like so:
#pragma message("...some compilation-time message...")
Is there an equivalent in GCC?
- 1,486
1
vote
0
answers
44
views
Is there a better way than passing /verbose to link.exe in order to see the effect of #pragma comment(lib, ...)?
#pragma comment(lib, ...) can be quite useful to declare library dependencies (static or import) from within a translation unit. As far as I am aware the way #pragma comment(lib, ...) works is by ...
- 21.3k
0
votes
1
answer
56
views
Increase speedup with OpenMP and reductions
I would increase speedup of these code with OpenMP.
for (i = 1; i < length; i++)
{
for (j = 1; j < i; j++)
sum_c += c[j];
c[i] = sum_c + W[i];
sum_c = 0;
}
I try with these ...
- 3
0
votes
2
answers
112
views
How to achieve RAII with #pragma's?
Currently, I have the following piece of code:
enum class Letters {
A,
B,
C
};
#pragma GCC diagnostic push
#pragma GCC diagnostic error "-Wswitch"
Letters e(Letters::A);...
- 3
0
votes
1
answer
85
views
How to pass no argument into pragma comment in c++
I want my program to show the console window if it detects the solution configuration is debug. If it detects release, then the console window should not show up
#include "Window.h"
int ...
- 37
0
votes
1
answer
183
views
Visual Studio Stop Refactoring Away Using In Specific Area
Usually, I can disable an annoying warning by wrapping two pragma warning disable statements around it. For instance:
#pragma warning disable IDE0060
public static int MultiplyByZero(int Number)
=&...
- 468
4
votes
1
answer
639
views
Hashing function Sha256 in Circom
During the hackathon ETH Global Paris Was attempting to integrate a circom circuit with hashing a birthday date to prove that the user know the date following a well known medium tutorial. Here is its ...
- 779
1
vote
1
answer
250
views
Is it possible to tell the compiler to only ignore specific unknown pragma?
I am not sure where I saw it first, but I got used to using #pragma region region name and #pragma endregion to mark sections in class definitions that belong together, like operator implementations.
...
- 52.9k
0
votes
1
answer
154
views
C optimization with pragmas, does it recurse? Or does it simply use look at the order of the pragmas in the file?
Lets say we have project wide optimisation disabled (eg -O0) for my project and I did the following. Edit: I am using tricore-gcc (should be the same as normal GCC). There is no documentation I can ...
- 2,760
1
vote
1
answer
950
views
Using pragmas efficiently in C++
I am a competitive programmer and I use pragmas for my codes. The pragmas that I use are:
#pragma GCC optimize("O3")
#pragma GCC optimization("Ofast,unroll-loops")
#pragma GCC ...
- 21
0
votes
0
answers
273
views
GCC Pragma region error: expected expression before ‘#pragma’
I'm trying to fold elements in an array with #pragma region and #pragma endregion directives, but every time I compile it I get:
gcc -ffreestanding -fshort-wchar -fno-stack-protector -Wall -Wno-...
1
vote
1
answer
73
views
Are _Pragma operators allowed in the middle of function prototype declarations?
I've encountered some code like this:
void _Pragma("function") f() {
int i = 0;
_Pragma("loop");
while (i < 100) {
...
}
}
GCC compiles it without issues. But I don'...
- 8,893
-1
votes
1
answer
97
views
Problem with outer loop vectorization using OpenMP in C
I am lerning how to use OpenMP to make a code use muttiple processors. Recently, I tried to make my Ewald Summation Fourier part parallel using OpenMP. Below is the function named ...
- 3
1
vote
1
answer
310
views
Avoiding warning 8-bit Ada Boolean return type, use Char
I have been working on cleaning up warnings on pedantic code, and we treat warnings as errors. I have interface code between Ada and C++, which looks like this:
Ada manager.ads:
function Foo(ID_Type : ...
- 69
5
votes
1
answer
687
views
Why is gcc not ignoring comment as error when using #pragma GCC diagnostic ignored "-Wcomment"?
I have some comments that have some macro examples. To make them more readable, I end the line with a \ to continue the macro on the next line. I'd rather not put a space after the \ to remove the ...
- 10.9k
2
votes
2
answers
215
views
what does two __pragma inside a define macro means?
I am trying to understand one line of code having two __pragma operatores inside one define macro:
#define NULL (_Pragma("nomisrac 10.5") 0 _Pragma("nomisrac restore"))
I know ...
- 31
1
vote
2
answers
256
views
Suppressing warnings for a printf-like function in C++
I have a legacy logging printf-like function in C:
namespace legacy
{
void DoLog(const char* format,...);
}
If is only visible if a corresponding macro is defined (this is legacy too):
#ifdef LOG
...
2
votes
0
answers
198
views
How to undefine symbol for a C# project
I have a C# project defining a symbol named WIN:
<PropertyGroup Condition="'$(Configuration)|$(Platform)'=='Release|AnyCPU'">
<DefineConstants>$(DefineConstants);WIN</...
- 3,539
-1
votes
1
answer
184
views
How to mark a code section with a warning purposely in C#?
is it possible to for example use #pragma to raise a custom warning within the VS IDE? I'd need it for a while because there are two classes in this code that contain the very same data but derive ...
- 241
1
vote
0
answers
170
views
I don't understand this mistake about #pragma
This is the first part of my code and I can't understand the mistake written at the end of the message. Maybe I don't know enough to understand it. I would be very grateful if someone can explain me ...
2
votes
1
answer
808
views
How do I fix this css prop horror show using emotion/twin.macro?
I am struggling to get my twin.macro setup working in my React app. I cannot provide an entire history of what I've tried, since I have tried dozens of different things, but I will outline my current ...
- 12.6k
0
votes
0
answers
54
views
C open mp wrong calculation without print
#include<stdio.h>
#include<omp.h>
#include<stdlib.h>
float FloatRandomizer(float a, float b)
{
float randomNumber = (a + (float)rand() / (float)(RAND_MAX / b));
if (...
0
votes
1
answer
505
views
Testing a Flash Loan Smart Contract - Have some issues
I am making a smart contract as I'm still learning solidity and practicing. I wrote the code, and I am receiving this error on Remix:
contracts/flash.sol:8:1: ParserError: Expected pragma, import ...
- 3
0
votes
2
answers
252
views
Filtering vector onto another vector in Parallel
I'm trying to filter a vector into another vector in parallel. My current setup generates too much overhead so it's even slower than serial. Concretely:
#pragma omp parallel for collapse(2)
for(int i =...
1
vote
1
answer
163
views
Where to find C #pragma syntax parameters
Where to find C #pragma syntax parameters.
i can't find a specific description in compiler doc,and also in c99 manual
find #pragma helper for specify paltform, such as for aarch64 platform, C ...
- 13
0
votes
1
answer
149
views
How to best parallelize nested for loop that calls a variable update function?
I'm trying to parallelize a nested for loop in OpenMP (C++) that sort of looks like this:
for(i = 0 ; i < a.size() ; i++){
for(j = 0 ; j < a.size() ; j++){
if(i!=j)
a[i].update(...
0
votes
1
answer
262
views
How can I selectively disable warnings in different build targets using #pragma warning disable?
I have a solution which multi-targets net framework 4.8.1 and Net 6. The code needs to run on both Linux and Windows, so I need to bifurcate code with appropriate #if NET481 statements and this ...
- 344
1
vote
1
answer
251
views
Unable to implement Dijkstra's Algorithm using OpenMP in C
I am trying to parallelize Dijkstra using OpenMP, but the program is not working correctly. Sometimes the correct results are displayed while other times I get wrong values, I assume this is because ...
- 19
1
vote
0
answers
137
views
#pragma GCC unroll with compile-time argument
Is there a way to unroll a loop in GCC based on compile-time (e.g., template) parameter?
The following does not compile, unless I replace unroll(N) with a concrete integer like unroll(8)
template<...
- 4,745
0
votes
1
answer
173
views
In which object file will a function be defiined if it the function definition is within a class definition? [duplicate]
I found out that if you put the function defintion outside of the class, but within the .h file, a Linker error will be thrown as the function is already defined in the main.obj. That makes sense. So, ...
- 1
0
votes
1
answer
116
views
Pragma omp parallel for - more nested for loops
What is the best way to parallel more then two for (nested) loops inside some other for loop? So for examlpe there is four for loops inside another one
For{ for{...} for{...}for{...}for{...}}
When I ...
