You can use `strcmp`:

    break x:20 if strcmp(y, &quot;hello&quot;) == 0

`20` is line number, `x` can be any filename and `y` can be any variable.

Use a [break condition](https://sourceware.org/gdb/current/onlinedocs/gdb/Conditions.html)  with `$_streq` (one of GDB&#39;s own [convenience functions](https://sourceware.org/gdb/current/onlinedocs/gdb/Convenience-Funs.html#Convenience-Funs &quot;current convenience functions online documentation&quot;)):
```gdb
break [where] if $_streq(x, &quot;hello&quot;)
```
or, if your breakpoint already exists, add the condition to it:
```gdb
condition &lt;breakpoint number&gt; $_streq(x, &quot;hello&quot;)
```

[Since GDB 7.5 (long ago)](https://sourceware.org/git/gitweb.cgi?p=binutils-gdb.git;a=commit;h=a72c32530ec5ee0b1baf366ba99db5f2e83681cb &quot;git commit, released 2012-08-17&quot;) you can use that and a handful of other native [convenience functions](https://sourceware.org/gdb/current/onlinedocs/gdb/Convenience-Funs.html#Convenience-Funs &quot;current online documentation&quot;) for various string matching, including `$_regex` which supports the [Python regex syntax](https://docs.python.org/3/library/re.html#regular-expression-syntax):
```gdb
$_memeq(buf1, buf2, length)
$_regex(str, regex)
$_streq(str1, str2)
$_strlen(str)
```

These are quite less problematic than having to execute the usual `strcmp()` injected to the process&#39; stack, because that can have undesired side effects.

Alas, using the native functions is not always possible, because they rely on GDB being compiled with Python support. This is usually the default, but some constrained environments might not have it. To be sure, you can check it by running `show configuration` inside GDB and searching for `--with-python`. This shell oneliner does the trick, too:
```sh
gdb -n -quiet -batch -ex &#39;show configuration&#39; | grep &#39;with-python&#39;
```

    break x if ((int)strcmp(y, &quot;hello&quot;)) == 0

On some implementations gdb might not know the return type of strcmp. That means you would have to cast, otherwise it would always evaluate to true!

I simply want to have an .ico file that has multiple sizes of the icon image contained within it.  I&#39;d like it for use in a cross-platform desktop application (so that, e.g. on Windows, the 16x16 size is used for the app&#39;s top bar but a 32x32 size version is used when the various open apps are shown when using Alt-Tab).  Once I have that .ico file, I know how to use it within my widget toolkit to get this effect, but I don&#39;t know how to get it.

What process should I use to make such a file?

How to make/get a multi size .ico file?

I have a model similar to this:

    public class SampleModel
    {
         public Product Product { get; set; } 
    }

And in my controller I get an exception trying to print out

    @Html.TextBoxFor(p =&gt; p.Product.Name)

This is the error:

&lt;!-- language: lang-none --&gt;

    Exception: An expression tree may not contain a dynamic operation


If anyone can give me some clues on how to fix this I would really appreciate it!

Razor View Engine : An expression tree may not contain a dynamic operation

Can I specify that I want gdb to break at line x when `char* x` points to a string whose value equals `&quot;hello&quot;`? If yes, how?



How do I set a conditional breakpoint in gdb, when char* x points to a string whose value equals &quot;hello&quot;?

<p>Can I specify that I want gdb to break at line x when <code>char* x</code> points to a string whose value equals <code>"hello"</code>? If yes, how?</p>


In C/C++, the main function receives parameters which are of type `char*`.

    int main(int argc, char* argv[]){
      return 0;
    }

`argv` is an array of `char*`, and points to strings. Where are these string located? Are they on the heap, stack, or somewhere else?

Where are C/C++ main function&#39;s parameters?

I&#39;m very new to dealing with bits and have got stuck on the following warning when compiling:

&gt;      7: warning: left shift count &gt;= width of type

My line 7 looks like this

    unsigned long int x = 1 &lt;&lt; 32;

This would make sense if the size of `long` on my system was 32 bits. However, `sizeof(long)` returns `8` and `CHAR_BIT` is defined as `8` suggesting that long should be 8x8 = 64 bits long.

What am I missing here? Are `sizeof` and `CHAR_BIT` inaccurate or have I misunderstood something fundamental?

warning: left shift count &gt;= width of type

I&#39;m trying to write an ftp server on Linux. In this matter how can I list files in the directory on terminal by a C program? Maybe I can use exec function to run find command but I want file name as a string to send client program. How can I do this?

Thanks for answers.

How to list files in a directory in a C program?

What is the `exec()` function and its family?  Why is this function used and how does its work?

Please anyone explain these functions.

Please explain the exec() function and its family

For example, I have this

    char *buff = &quot;this is a test string&quot;;

and want to get `&quot;test&quot;`. How can I do that?

Get a substring of a char*

How do I verify the existence of an object in JavaScript?

The following works:

    if (!null)
       alert(&quot;GOT HERE&quot;);

But this throws an Error:

    if (!maybeObject)
       alert(&quot;GOT HERE&quot;);

**The Error:** 
&gt;`maybeObject` is not defined.



Check if object exists in JavaScript

I&#39;m a total noob at Android programming, and wanted to learn how to debug my apps.  I can&#39;t seem to have my Log.i|d|v calls displayed in the LogCat.  

Here&#39;s the code that I&#39;m using.  As you can see I have defined a LOG_TAG constant, but can&#39;t seem to find it in the LogCat.  I have also imported android.util.Log AND I have made sure that in my AndroidManifest I have &quot;debuggable&quot; set to TRUE.

I have also checked http://developer.android.com/reference/android/util/Log.html w/o any luck resolving this issue.  

What am I doing wrong?  Am I even looking in the right place?  I&#39;ve tried using the DDMS and Debug perspective as well w/o any luck.  Any help to this noob would be greatly appreciated.  Thanks.

My environment:
Windows XP
IDE = Eclipse Version: 3.6.1, Build id: M20100909-0800
Emulator = having it point to android sdk 2.1 api 7


//very basic HELLO World code with a couple of Log.i calls

    import android.app.Activity;
    import android.os.Bundle;
    import android.util.Log;
    
    public class debugger extends Activity {
    	private static final String LOG_TAG = &quot;debugger&quot;;
    	
        /** Called when the activity is first created. */
        @Override
        public void onCreate(Bundle savedInstanceState) {
        	Log.i(LOG_TAG, &quot;line 13&quot;);
        	super.onCreate(savedInstanceState);
            setContentView(R.layout.main);
            
            Log.i(LOG_TAG, &quot;CREATING NOW&quot;);
        }
    }

Logcat not displaying my log calls

Is there a way to launch an IPython shell or prompt when my program runs a line that raises an exception?

I&#39;m mostly interested in the context, variables, in the scope (and subscopes) where the exception was raised. Something like Visual Studio&#39;s debugging, when an exception is thrown but not caught by anyone, Visual Studio will halt and give me the call stack and the variables present at every level.

Do you think there&#39;s a way to get something similar using IPython?

**EDIT:** The `-pdb` option when launching IPython doesn&#39;t seem do what I want (or maybe I don&#39;t know how to use it properly, which is entirely possible). I run the following script : 

    def func():
        z = 2
        g = &#39;b&#39;
        raise NameError(&quot;This error will not be caught, but IPython still&quot;
                        &quot;won&#39;t summon pdb, and I won&#39;t be able to consult&quot;
                        &quot;the z or g variables.&quot;)
        
    x = 1
    y = &#39;a&#39;
    
    func()

Using the command : 

    ipython -pdb exceptionTest.py

Which stops execution when the error is raised, but brings me an IPython prompt where I have access to the global variables of the script, but not the local variables of function func. `pdb` is only invoked when I directly type a command in ipython that causes an error, i.e. `raise NameError(&quot;This, sent from the IPython prompt, will trigger pdb.&quot;)`.

I don&#39;t necessarily need to use `pdb`, I&#39;d just like to have access to the variables inside `func`.

**EDIT 2:** It has been a while, IPython&#39;s `-pdb` option is now working just as I want it to. That means when I raise an exception I can go back in the scope of `func` and read its variables `z` and `g` without any problem. Even without setting the `-pdb` option, one can run IPython in interactive mode then call the magic function `%debug` after the program has exit with error -- that will also drop you into an interactive ipdb prompt with all scopes accessibles. 

Launch an IPython shell on exception

Would anyone know how I can view what a cursor has in it during debugging so that I can determine the functionality of my database helper?

It keeps acting like it&#39;s returning data, but then when I attempt to use the `cursor.isNull(0)` method, I keep getting `NullPointerException` thrown and not being able to see what the cursor has in it while stepping through the execution is really frustrating me.

Any help would be extremely appreciated.

Thanks.

Viewing an Android database cursor

I come from a C++ background, so apologies if this is a non-C# way of thinking, but I just need to know. :)

In C++ if I have two pointers, and I want to know if they point to the same thing, I can look in the memory/watch window and see their value - to see if they are pointing to the same memory space.

In C#, I haven&#39;t been able to find something along those lines.  One reference type with exactly the same values could in fact be the exact same object, or it could be something wildly different.

Is there a way for me to see this kind of information in C#?  Perhaps some kind of equivalent to the &amp; operator for the watch window or some such?

Uniquely Identifying Reference Types in the Debugger

**How can I set a breakpoint in C or C++ code programatically that will work for gdb on Linux?**

*I.e.:*

    int main(int argc, char** argv)
    {
        /* set breakpoint here! */
        int a = 3;
        a++;  /*  In gdb&gt; print a;  expect result to be 3 */
        return 0;
    }



Set breakpoint in C or C++ code programmatically for gdb on Linux

I can add a breakpoint in GDB with:

    b &lt;filename&gt;:&lt;line no&gt;

How can I remove an existing breakpoint at a particular location?





How do I remove a single breakpoint with GDB?

Consider:

    (gdb) q
    A debugging session is active.

            Inferior 1 [process 9018] will be killed.

    Quit anyway? (y or n) y

What is a `.gdbinit` option to make GDB always kill the running process at a quit request?

I know that GDB can attach to already-running processes, so it would be bad to kill them at quit. But for a processes started from it, a need to confirm your actions starts to annoy at a second quit.


Get rid of &quot;quit anyway&quot; prompt using GDB: Just kill the process and quit

I usually run a program as :

    ./a.out arg1 arg2 &lt;file

I would like to debug it using gdb.

I am aware of the `set args` functionality, but that only works from the gdb prompt.

How to pass arguments and redirect stdin from a file to program run in gdb?

I have a multithreaded C program, which consistently generates a segmentation fault at a specific point in the program. When I run it with gdb, no fault is shown. Can you think of any reason why the fault might occur only when not using the debugger? It&#39;s pretty annoying not being able to use it to find the problem!

segfault only when NOT using debugger

I want to know how to place a conditional breakpoint in Eclipse. I have a code like:

    public static void doForAllTabs(String[] tablist){
        for(int i = 0; i&lt;tablist.length;i++){
    --&gt;        doIt(tablist[i]);
        }
    }

Now I want to put a breakpoint on the line with the arrow but want it to trigger only if:

    tablist[i].equalsIgnoreCase(&quot;LEADDELEGATES&quot;);


How to use conditional breakpoint in Eclipse?

I am using Visual Studio 2010, and I know this feature is available in C++.

I need to debug some code, that changes a variable to several values. I want to debug the code in a specific case, when the variable getting a specific value. I know I can add `if(var == value)`, but is there any elegant way to do it?

Another question, can I set a breakpoint when a variable is changed in general?


Content Type	Original Author	Original Content on Stackoverflow
Question	341008	View Question on Stackoverflow
Solution 1 - C	Nathan Fellman	View Answer on Stackoverflow
Solution 2 - C	tlwhitec	View Answer on Stackoverflow
Solution 3 - C	Tobias Domhan	View Answer on Stackoverflow

How do I set a conditional breakpoint in gdb, when char* x points to a string whose value equals "hello"?

C Problem Overview

C Solutions

Solution 1 - C

Solution 2 - C

Solution 3 - C

Razor View Engine : An expression tree may not contain a dynamic operation

How to make/get a multi size .ico file?

Attributions