This problem asks me about a possible number I could replace HUH? with so that it prints hello world and then terminates without any errors.
I tried to figure out the address of x in the main function and used some hexadecimal subtraction between the local variable x in the doit function and the address of x in the main function, but no avail. Is there a way for me to perhaps access the contents of the x in the main function and change that value to 0?
Doing so would cause the while loop to stop running and print out "Hello World".
Is this a feasible approach?
void doit(void) {
int x[1];
x[HUH ? ] = 0;
}
int main(void)
{
int x = 1;
while (x > 0)
{
doit();
}
printf("hello world");
}
No. The only valid index inside x is 0. Any other would trigger undefined behaviour by out-of-bounds access, and x is not used otherwise so you won't get any side-effect out of it.
For example, Clang 7 on Godbolt completely ignores the access and optimizes doit to a simple ret in all cases.
Unless, of course, you cram the side effect into the index expression:
x[std::printf("hello world"), std::exit(0), 0] = 0;
I would like to use a breakpoint to execute code in Visual Studio 2017 and have the side effects of that code affect the program. It appears from Execute code when breakpoint is hit? that this was possible in a past version of Visual Studio.
But consider the code below.
int Counter = 0;
public bool Increment()
{
Counter++;
return false;
}
public void PrintNumbers()
{
for (int i = 0; i < 3; i++)
{
Debug.WriteLine($"Iteration {i}");
}
Debug.WriteLine("Counter: " + Counter);
}
I have set a breakpoint on the line that runs the "Iteration" as follows:
When this runs, it produces the following output:
Iteration 0
Iteration 1
Iteration 2
Counter: 0
This is a true technological marvel! Visual Studio does run the code -- if I change the "return false" in Increment() to "return true," the breakpoint will be hit. But it magically avoids side effects. That's great! But I want side effects. In other words, I really want an action option besides "log a message to output windows" that allows execution of code with side effects. Is there any way around this Visual Studio feature?
You might be wondering why I want to do this. I would like to make a conditional breakpoint dependent on another conditional breakpoint having been passed. (For example, I know that the Knight is talking funny after meeting the Princess, so I want to put a breakpoint on KnightTalks() that stops only if some code in KnightMeetsPrincess() has executed. I run into situations this all the time and get annoyed when I have to disable the KnightTalks breakpoint and reenable it after KnightMeetsPrincess, especially when there is a longer chain of events.) Based on Conditional breakpoint depends on other breakpoint, I think there is no built-in way to do this. But I could do something like it if I could execute arbitrary code -- for example, if I could set and get a pseudovariable. Or one could use code like the following:
public static class Bookmark
{
static Dictionary<string, int> HitCounts = new Dictionary<string, int>();
public static bool Set(string s)
{
if (!HitCounts.ContainsKey(s))
HitCounts[s] = 1;
else
HitCounts[s]++;
return false;
}
public static bool Set(string s, bool condition)
{
if (condition)
Set(s);
return false;
}
public static bool Get(string s)
{
return HitCounts.ContainsKey(s);
}
}
The idea of this code was that I would put a conditional breakpoint on KnightMeetsPrincess that called Bookmark.Set("KnightMeetsPrincess") and then on KnightTalks, a separate conditional breakpoint called Bookmark.Get("KnightMeetsPrincess"). Alas, this doesn't work because the code executes, but without side effects.
Any workarounds?
Quick question: I have a csv file that contains 360 rows and 3 columns. Each cell or matrix entry is a type double (for example: 1.0000000, 0.9314933, 0.9866587). I was thinking the following code would get the entries:
//construct 2-d array
float CDF_inputs[360][3];
std::ifstream file("filename");
for(int row = 0; row < 360; ++row)
{
std::string line;
std::getline(file, line);
if ( !file.good() )
break;
std::stringstream iss(line);
for (int col = 0; col < 3; ++col)
{
std::string val;
std::getline(iss, val, ',');
if ( !iss.good() )
break;
std::stringstream convertor(val);
convertor >> CDF_inputs[row][col];
}
}
The file only contains doubles, no other characters (than the commas). I run the code, it builds (visual studio c++) and there are no errors. However I do not believe it is working correctly.
Is the given code correct?
How can I debug, or "print to console" either the array or an error message if the file is bad, or if the array fails to "load"?
Thanks first post for me.
I think you are learning. Well, you can place breakpoint by hitting F9 on a appropriate source code line and execute your code line-by-line by pressing F10 button. So, while debugging, you can hold mouse pointer on variables to see what they contain.
I have assumed that you are using Visual Studio.
Good Luck.
So, here is a countdown.
My aim is the next: if you don't do anything for the given time (ent_sec) the countdown will reach 0 after a time and return with 0, BUT if you press down the letter c (code: 99) the countdown stops and you can enter your PIN code and return with it.
I have already solved the problem with Windows.h in the next way:
if (GetAsyncKeyState(VK_SPACE))
This solves the problem is through WIN32 API (in this case you have to press SPACE, not letter 'c'), but it revealed that I can't use any WinAPI function (school project). So I rewrite this line to the following:
if (getchar() == 99)
But unfortunately it doesn't work in the proper way, cause my countdown stops in almost every second until I dont't press some "wrong" key (for example I press 'x', then the countdown goes forward, but in the next sec it stops again)... In the first solution (win func) this problem doesn't exist... So how can I fix that? Thanks. Here is the whole code of my function:
unsigned Timer::DownCount
{
int ent_sec = this.time;
cout << "The counter has started (" << this.time << "sec), press 'C' to enter your PIN code: " << endl;
while (ent_sec >= 0)
{
if (getchar() == 99) // c letter's code is 99 in ANSI (or ASCII dunno)
{
unsigned code;
cout << "PIN code: ";
cin >> code;
return code;
}
else
{
SecCounter(1); // this function counts 1 secundum
cout << ent_sec << endl;
ent_sec--;
}
}
return 0;
}
I don't believe there's a standard way to do this that will work across all platforms, but here's one way of doing it that will work on Windows without actually using Windows API functions.
int getch_nowait()
{
if (!kbhit()) return -1;
return getch();
}
Then your check just becomes if (getch_nowait() == 99) ...
This code may be compiler specific. If it doesn't work for you, it'll help if you tell us what compiler and operating system you are using.
I have a utility (grep) that gives me a list of filenames and a line numbers. After I have determined that devenv is the correct program to open a file, I would like to ensure that it is opened at the indicated line number. In emacs, this would be:
emacs +140 filename.c
I have found nothing like this for Visual Studio (devenv). The closest I have found is:
devenv /Command "Edit.Goto 140" filename.c
However, this makes a separate instance of devenv for each such file. I would rather have something that uses an existing instance.
These variations re-use an existing devenv, but don't go to the indicated line:
devenv /Command "Edit.Goto 140" /Edit filename.c
devenv /Command /Edit filename.c "Edit.Goto 140"
I thought that using multiple "/Command" arguments might do it, but I probably don't have the right one because I either get errors or no response at all (other than opening an empty devenv).
I could write a special macro for devenv, but I would like this utility to be used by others that don't have that macro. And I'm not clear on how to invoke that macro with the "/Command" option.
Any ideas?
Well, it doesn't appear that there is a way to do this as I wanted. Since it looks like I'll need to have dedicated code to start up Visual Studio, I've decided to use EnvDTE as shown below. Hopefully this will help somebody else.
#include "stdafx.h"
//-----------------------------------------------------------------------
// This code is blatently stolen from http://benbuck.com/archives/13
//
// This is from the blog of somebody called "BenBuck" for which there
// seems to be no information.
//-----------------------------------------------------------------------
// import EnvDTE
#pragma warning(disable : 4278)
#pragma warning(disable : 4146)
#import "libid:80cc9f66-e7d8-4ddd-85b6-d9e6cd0e93e2" version("8.0") lcid("0") raw_interfaces_only named_guids
#pragma warning(default : 4146)
#pragma warning(default : 4278)
bool visual_studio_open_file(char const *filename, unsigned int line)
{
HRESULT result;
CLSID clsid;
result = ::CLSIDFromProgID(L"VisualStudio.DTE", &clsid);
if (FAILED(result))
return false;
CComPtr<IUnknown> punk;
result = ::GetActiveObject(clsid, NULL, &punk);
if (FAILED(result))
return false;
CComPtr<EnvDTE::_DTE> DTE;
DTE = punk;
CComPtr<EnvDTE::ItemOperations> item_ops;
result = DTE->get_ItemOperations(&item_ops);
if (FAILED(result))
return false;
CComBSTR bstrFileName(filename);
CComBSTR bstrKind(EnvDTE::vsViewKindTextView);
CComPtr<EnvDTE::Window> window;
result = item_ops->OpenFile(bstrFileName, bstrKind, &window);
if (FAILED(result))
return false;
CComPtr<EnvDTE::Document> doc;
result = DTE->get_ActiveDocument(&doc);
if (FAILED(result))
return false;
CComPtr<IDispatch> selection_dispatch;
result = doc->get_Selection(&selection_dispatch);
if (FAILED(result))
return false;
CComPtr<EnvDTE::TextSelection> selection;
result = selection_dispatch->QueryInterface(&selection);
if (FAILED(result))
return false;
result = selection->GotoLine(line, TRUE);
if (FAILED(result))
return false;
return true;
}
With VS2008 SP1, you can use the following command line to open a file at a specific line in an existing instance :
devenv /edit FILE_PATH /command "edit.goto FILE_LINE"
Source
Elaborating on Harold question and answer, I adapted the C++ solution (that I first adopted) to C#. It is much simpler (that is my first C# program!). One just need to create a project, add references to "envDTE" and "envDTE80" and drop the following code:
using System;
using System.Collections.Generic;
using System.Text;
namespace openStudioFileLine
{
class Program
{
[STAThread]
static void Main(string[] args)
{
try
{
String filename = args[0];
int fileline;
int.TryParse(args[1], out fileline);
EnvDTE80.DTE2 dte2;
dte2 = (EnvDTE80.DTE2)System.Runtime.InteropServices.Marshal.GetActiveObject("VisualStudio.DTE");
dte2.MainWindow.Activate();
EnvDTE.Window w = dte2.ItemOperations.OpenFile(filename, EnvDTE.Constants.vsViewKindTextView);
((EnvDTE.TextSelection)dte2.ActiveDocument.Selection).GotoLine(fileline, true);
}
catch (Exception e)
{
Console.Write(e.Message);
}
}
}
}
One then just calls openStudioFileLine path_to_file numberOfLine.
Hope that may help !
Based on reder answer I have published repository with source, here is binary(.net2.0)
I also add support for multiple VS versions
usage: <version> <file path> <line number>
Visual Studio version value
VisualStudio 2002 2
VisualStudio 2003 3
VisualStudio 2005 5
VisualStudio 2008 8
VisualStudio 2010 10
VisualStudio 2012 12
VisualStudio 2013 13
Example using from GrepWin:
VisualStudioFileOpenTool.exe 12 %path% %line%
Pretty old thread, but it got me started so here's another example. This AutoHotkey function opens a file, and puts the cursor on a particular rowand column.
; http://msdn.microsoft.com/en-us/library/envdte.textselection.aspx
; http://msdn.microsoft.com/en-us/library/envdte.textselection.movetodisplaycolumn.aspx
VST_Goto(Filename, Row:=1, Col:=1) {
DTE := ComObjActive("VisualStudio.DTE.12.0")
DTE.ExecuteCommand("File.OpenFile", Filename)
DTE.ActiveDocument.Selection.MoveToDisplayColumn(Row, Col)
}
Call with:
VST_Goto("C:\Palabra\.NET\Addin\EscDoc\EscDoc.cs", 328, 40)
You could translate it pretty much line by line to VBScript or JScript.
Here is Python variation of Harold's solution:
import sys
import win32com.client
filename = sys.argv[1]
line = int(sys.argv[2])
column = int(sys.argv[3])
dte = win32com.client.GetActiveObject("VisualStudio.DTE")
dte.MainWindow.Activate
dte.ItemOperations.OpenFile(filename)
dte.ActiveDocument.Selection.MoveToLineAndOffset(line, column+1)
It shows how to go to specified line + column.
Here is VBS variation of Harold's solution: link to .vbs script.
open-in-msvs.vbs full-path-to-file line column
Windows supports VBScript natively - no need for compilation or any additional interpreters.
These C# dependencies on project references are completely unecessary. Indeed much of the code here is overly verbose. All you need is this.
using System.Reflection;
using System.Runtime.InteropServices;
private static void OpenFileAtLine(string file, int line) {
object vs = Marshal.GetActiveObject("VisualStudio.DTE");
object ops = vs.GetType().InvokeMember("ItemOperations", BindingFlags.GetProperty, null, vs, null);
object window = ops.GetType().InvokeMember("OpenFile", BindingFlags.InvokeMethod, null, ops, new object[] { file });
object selection = window.GetType().InvokeMember("Selection", BindingFlags.GetProperty, null, window, null);
selection.GetType().InvokeMember("GotoLine", BindingFlags.InvokeMethod, null, selection, new object[] { line, true });
}
Simples eh?
This is my working C# solution for Visual Studio 2017 (15.9.7)
For other versions of VS just change the version number (i.e. "VisualStudio.DTE.14.0")
todo:
Add Reference->Search 'envdte'->Check Checkbox for envdte->Click OK
using EnvDTE;
private static void OpenFileAtLine(string file, int line)
{
DTE dte = (DTE) Marshal.GetActiveObject("VisualStudio.DTE.15.0");
dte.MainWindow.Visible = true;
dte.ExecuteCommand("File.OpenFile", file);
dte.ExecuteCommand("Edit.GoTo", line.ToString());
}
For reference here is the ENVDE written in C# (using O2 Platform inside VisualStudio to get a reference to the live DTE object)
var visualStudio = new API_VisualStudio_2010();
var vsDTE = visualStudio.VsAddIn.VS_Dte;
//var document = (Document)vsDTE.ActiveDocument;
//var window = (Window)document.Windows.first();
var textSelection = (TextSelection)vsDTE.ActiveDocument.Selection;
var selectedLine = 1;
20.loop(100,()=>{
textSelection.GotoLine(selectedLine++);
textSelection.SelectLine();
});
return textSelection;
This code does a little animation where 20 lines are selected (with a 100ms interval)
The correct wingrep command line syntax to force a new instance and jump to a line number is:
"C:\Program Files (x86)\Microsoft Visual Studio 14.0\Common7\IDE\devenv.exe" $F /command "edit.goto $L"
Replace the studio version number with the correct version for your setup.
The version posted by #Mungo64 worked for me, but of course the version number is always changing, so I made a version that automatically searches until we find it.
Add Reference->Search 'envdte'->Check Checkbox for envdte->Click OK
//using EnvDTE; //I didn't use the using directive as it causes ambiguity in another module I'm using.
private static void OpenFileAtLine(string file, int line)
{
//The number needs to be rolled to the next version each time a new version of visual studio is used...
EnvDTE.DTE dte = null;
for (int i = 25; i > 8; i--) {
try
{
dte = (EnvDTE.DTE)Marshal.GetActiveObject("VisualStudio.DTE." + i.ToString() + ".0");
}
catch (Exception ex)
{
//don't care... just keep bashing head against wall until success
}
}
//the following line works fine for visual studio 2019:
//EnvDTE.DTE dte = (EnvDTE.DTE)Marshal.GetActiveObject("VisualStudio.DTE.16.0");
dte.MainWindow.Visible = true;
dte.ExecuteCommand("File.OpenFile", file);
dte.ExecuteCommand("Edit.GoTo", line.ToString());
}
I can't figure out a way to do this with straight command-line options. It looks like you will have to write a macro for it. Supposedly, you can invoke them like so.
devenv /command "Macros.MyMacros.Module1.OpenFavoriteFiles"
So, you can probably create a macro that takes a filename and a line number, then opens the file and jumps to the proper place. But, I don't know that you can specify a same-instance flag somewhere, or not.
I was about to ask this question because when you get the "yellow screen of death" when debugging a web application, you want to quickly go to the file and line that it gives you in the stacktrace e.g:
[ContractException: Precondition failed: session != null]
System.Diagnostics.Contracts.__ContractsRuntime.TriggerFailure(ContractFailureKind kind, String msg, String userMessage, String conditionTxt, Exception inner) in C:\_svn\IntegratedAdaptationsSystem\Source\IntegratedAdaptationsSystem\IAS_UI\Controllers\CustomErrorsPageController.cs:0
System.Diagnostics.Contracts.__ContractsRuntime.ReportFailure(ContractFailureKind kind, String msg, String conditionTxt, Exception inner) in C:\_svn\IntegratedAdaptationsSystem\Source\IntegratedAdaptationsSystem\IAS_UI\Controllers\CustomErrorsPageController.cs:0
System.Diagnostics.Contracts.__ContractsRuntime.Requires(Boolean condition, String msg, String conditionTxt) in C:\_svn\IntegratedAdaptationsSystem\Source\IntegratedAdaptationsSystem\IAS_UI\Controllers\CustomErrorsPageController.cs:0
IAS_UI.Web.IAS_Session..ctor(HttpSessionStateBase session) in C:\_svn\IntegratedAdaptationsSystem\Source\IntegratedAdaptationsSystem\IAS_UI\Web\IAS_Session.cs:15
IAS_UI.Controllers.ServiceUserController..ctor() in C:\_svn\IntegratedAdaptationsSystem\Source\IntegratedAdaptationsSystem\IAS_UI\Controllers\ServiceUserController.cs:41
Say I want to go to ServiceUserController.cs at line 41. Usually I would open Visual Studio and do it manually but then I wrote a little Autohotkey script which does it.
To open it, you will highlight the filename and line number e.g. ServiceUserController.cs:41 and thereafter press your shortcut Alt + v. Here is the code for it:
$!v::
if (NOT ProcessExists("devenv.exe"))
{
MsgBox, % "Visual Studio is not loaded"
}
else
{
IfWinExist, Microsoft Visual Studio
{
ToolTip, Opening Visual Studio...
c := GetClip()
if (NOT c) {
MsgBox, % "No text selected"
}
else
{
WinActivate ; now activate visual studio
Sleep, 50
; for now assume that there is only one instance of visual studio - handling of multiple instances comes in later
arr := StringSplitF(c, ":")
if (arr.MaxIndex() <> 2) {
MsgBox, % "Text: '" . c . "' is invalid."
}
else {
fileName := arr[1]
lineNumber := arr[2]
; give focus to the "Find" box
SendInput, ^d
; delete the contents of the "Find" box
SendInput, {Home}
SendInput, +{End}
SendInput, {Delete}
; input *** >of FILENAME *** into the "Find" box
SendInput, >of{Space}
SendInput, % fileName
; select the first entry in the drop down list
SendInput, {Down}
SendInput, {Enter}
; lineNumber := 12 remove later
; open the go to line dialog
SendInput, ^g
Sleep, 20
; send the file number and press enter
SendInput, % lineNumber
SendInput {Enter}
}
}
ToolTip
}
}
return
You will want to paste the following "utility functions" before it:
GetClip()
{
ClipSaved := ClipboardAll
Clipboard=
Sleep, 30
Send ^c
ClipWait, 2
Sleep, 30
Gc := Clipboard
Clipboard := ClipSaved
ClipSaved=
return Gc
}
ProcessExists(procName)
{
Process, Exist, %procName%
return (ErrorLevel != 0)
}
StringSplitF(str, delimeters)
{
Arr := Object()
Loop, parse, str, %delimeters%,
{
Arr.Insert(A_LoopField)
}
return Arr
}
Using this command works for me, as long as Visual Studio is NOT open already.
"C:\Program Files (x86)\Microsoft Visual Studio 14.0\Common7\IDE\devenv.exe" /edit "ABSOLUTEFILEPATH_FILENAME.CPP" /command "Edit.GoTo 164"
If it is already open, then sometimes it works and goes to the right line, but then it just stops working and I have never figured out why. Looks like Microsoft is aware of the issue but have said they "Will Not Fix" it, unless more people complain. So if it's still an issue I'd suggest commenting here: https://connect.microsoft.com/VisualStudio/Feedback/Details/1128717
Slightly simplified version of the answer from OnceUponATimeInTheWest:
using System.Runtime.InteropServices;
private static void OpenFileAtLine(string file, int line) {
dynamic vs = Marshal.GetActiveObject("VisualStudio.DTE");
dynamic window = vs.ItemOperations.OpenFile(path);
window.Selection.GotoLine(line, true);
}
It uses dynamics instead of Reflection to make the code a bit shorter and more readable.