Sure, find where `-Werror` is set and remove that flag. Then warnings will be only warnings.

You can make all warnings being treated as such using `-Wno-error`. You can make specific warnings being treated as such by using `-Wno-error=&lt;warning name&gt;` where `&lt;warning name&gt;` is the name of the warning you don&#39;t want treated as an error.

If you want to entirely _disable_ all warnings, use `-w` (not recommended).

---

Source: http://gcc.gnu.org/onlinedocs/gcc-4.3.2/gcc/Warning-Options.html

Solution:

    CFLAGS=-Wno-error ./configure



Remove `-Werror` from your Make or CMake files, as suggested [in this post][1]


  [1]: https://stackoverflow.com/a/10248526/2110769 &quot;in this post&quot;

`-Wall` and `-Werror` compiler options can cause it, please check if those are used in compiler settings.

If you are compiling linux kernel. For example, if you want to disable the warning that is &quot;unused-but-set-variable&quot; been treated as error. You can add a statement:

    KBUILD_CFLAGS += $(call cc-option,-Wno-error=unused-but-set-variable,)

in your Makefile

Thanks for all the helpful suggestions. I finally made sure that there are no warnings in my code, but again was getting this warning from sqlite3:

    Assuming signed overflow does not occur when assuming that (X - c) &lt;= X is always true

which I fixed by adding the following CFLAG:

    -fno-strict-overflow



I&#39;m trying to align an HTML button exactly at the centre of the page irrespective of the browser used. It is either floating to the left while still being at the vertical centre or being somewhere on the page like at the top of the page etc.. 

I want it to be both vertically and horizontally be centered. Here is what I have written right now:

    &lt;button type=&quot;button&quot; style=&quot;background-color:yellow;margin-left:auto;margin-right:auto;display:block;margin-top:22%;margin-bottom:0%&quot;&gt;
       mybuttonname
    &lt;/button&gt; 


trying to align html button at the center of the my page

I created a folder in s3 named &quot;test&quot; and I pushed &quot;test_1.jpg&quot;, &quot;test_2.jpg&quot; into &quot;test&quot;.

How can I use boto to delete folder &quot;test&quot;?

Amazon S3 boto - how to delete folder?

The problem is that the same code that compiles well on Windows, is unable to compile on Ubuntu. Every time I get this error:

    cc1: warnings being treated as errors

Now, it&#39;s big code base and I don&#39;t like fix all the warnings.

Is there any way I can compile successfully in spite of the warnings?

How to compile without warnings being treated as errors?

The problem is that the same code that compiles well on Windows, is unable to compile on Ubuntu. Every time I get this error:
<pre><code class="hljs language-vbnet">cc1: warnings being treated as errors
</code></pre>
Now, it's big code base and I don't like fix all the warnings.
Is there any way I can compile successfully in spite of the warnings?

How can I write a little piece of text into a `.txt` file?
I&#39;ve been Googling for over 3-4 hours, but can&#39;t find out how to do it.

`fwrite();` has so many arguments, and I don&#39;t know how to use it.

What&#39;s the easiest function to use when you only want to write a name and a few numbers to a `.txt` file?

    char name;
	int  number;
	FILE *f;
	f = fopen(&quot;contacts.pcl&quot;, &quot;a&quot;);
	
	printf(&quot;\nNew contact name: &quot;);
	scanf(&quot;%s&quot;, &amp;name);
	printf(&quot;New contact number: &quot;);
	scanf(&quot;%i&quot;, &amp;number);
	
	fprintf(f, &quot;%c\n[ %d ]\n\n&quot;, name, number);
	fclose(f);

Write to .txt file?

Came across an interesting interview question:

    test 1:
    printf(&quot;test %s\n&quot;, NULL);
    printf(&quot;test %s\n&quot;, NULL);
    
    prints:
    test (null)
    test (null)
    
    test 2:
    printf(&quot;%s\n&quot;, NULL);
    printf(&quot;%s\n&quot;, NULL);
    prints
    Segmentation fault (core dumped)
Though this might run fine on some systems, atleast mine is throwing a segmentation fault. 
What would be the best explanation of this behavior? Above code is in C.

Following is my gcc info:

    deep@deep:~$ gcc --version
    gcc (Ubuntu/Linaro 4.6.3-1ubuntu5) 4.6.3



What is the behavior of printing NULL with printf&#39;s %s specifier?

Today when I was reading others&#39; code, I saw something like `void *func(void* i);`, what does this `void*` mean here for the function name and for the variable type, respectively? 

In addition, when do we need to use this kind of pointer and how to use it? 


What does void* mean and how to use it?

I&#39;m trying to understand the use of `dup2` and `dup`. 

From the man page : 

    DESCRIPTION
    
    dup and dup2 create a copy of the file descriptor oldfd.
    After successful return of dup or dup2, the old and new descriptors may
    be used interchangeably. They share locks, file position pointers and
    flags; for example, if the file position is modified by using lseek on
    one of the descriptors, the position is also changed for the other.
    
    The two descriptors do not share the close-on-exec flag, however.
    
    dup uses the lowest-numbered unused descriptor for the new descriptor.
    
    dup2 makes newfd be the copy of oldfd, closing newfd first if necessary.  
    
    RETURN VALUE
    
    dup and dup2 return the new descriptor, or -1 if an error occurred 
    (in which case, errno is set appropriately).  

Why would I need that system call? what is the use of duplicating the file descriptor? 

If I have the file descriptor, why would I want to make a copy of it? 

I&#39;d appreciate if you could explain and give me an example where `dup2` / `dup` is needed. 

Thanks

dup2 / dup - why would I need to duplicate a file descriptor?

A number of answers for the Stack Overflow question https://stackoverflow.com/questions/11638091/getting-the-ieee-single-precision-bits-for-a-float suggest using a `union` structure for type punning (e.g.: turning the bits of a `float` into a `uint32_t`):

    union {
        float f;
        uint32_t u;
    } un;
    un.f = your_float;
    uint32_t target = un.u;

However, the value of the `uint32_t` member of the union appears to be unspecified according to the C99 standard (at least draft n1124), where section 6.2.6.1.7 states: 
&gt; When a value is stored in a member of an object of union type, the bytes of the object representation that do not correspond to that member but do correspond to other members take unspecified values.

At least one footnote of the C11 n1570 draft seems to imply that this is no longer the case (see footnote 95 in 6.5.2.3):
&gt;If the member used to read the contents of a union object is not the same as the member last used to
store a value in the object, the appropriate part of the object representation of the value is reinterpreted
as an object representation in the new type as described in 6.2.6 (a process sometimes called ‘‘type
punning’’). This might be a trap representation.

However, the text to section 6.2.6.1.7 is the same in the C99 draft as in the C11 draft.

Is this behavior actually unspecified under C99?  Has it become specified in C11?  I realize that most compilers seem to support this, but it would be nice to know if it&#39;s specified in the standard, or just a very common extension.

Is type-punning through a union unspecified in C99, and has it become specified in C11?

Is there `PRIu128` that behaves similar to `PRIu64` from `&lt;inttypes.h&gt;`:

    printf(&quot;%&quot; PRIu64 &quot;\n&quot;, some_uint64_value);


Or converting manually digit by digit:

    int print_uint128(uint128_t n) {
      if (n == 0)  return printf(&quot;0\n&quot;);
    
      char str[40] = {0}; // log10(1 &lt;&lt; 128) + &#39;\0&#39;
      char *s = str + sizeof(str) - 1; // start at the end
      while (n != 0) {
        if (s == str) return -1; // never happens
    
        *--s = &quot;0123456789&quot;[n % 10]; // save last digit
        n /= 10;                     // drop it
      }
      return printf(&quot;%s\n&quot;, s);
    }

is the only option?

Note that `uint128_t` is my own typedef for `__uint128_t`.

how to print __uint128_t number using gcc?

I would like to enable -- literally -- **ALL** of the warnings that GCC has. (You&#39;d think it would be easy...)

- You&#39;d think `-Wall` might do the trick, but nope! Still need `-Wextra`.

- You&#39;d think `-Wextra` might do the trick, but nope! Not all of the warnings listed [here](http://gcc.gnu.org/onlinedocs/gcc-4.4.0/gcc/Warning-Options.html) (for example, `-Wshadow`) are enabled by this. And I still have no idea if this list is comprehensive.

How do I tell GCC to enable (no if&#39;s, and&#39;s, or but&#39;s!) **all** the warnings it has?

How to turn on (literally) ALL of GCC&#39;s warnings?

In a C program I was trying the below operations (Just to check the behavior)

     x = 5 % (-3);
     y = (-5) % (3);
     z = (-5) % (-3); 
    
    printf(&quot;%d ,%d ,%d&quot;, x, y, z); 

It gave me output as `(2, -2 , -2)` in gcc. I was expecting a positive result every time. Can a modulus be negative? Can anybody explain this behavior?

Modulo operation with negative numbers

It is C language.It is written that:

    typedef struct __attribute__((packed, aligned(4))) Ball {
        float2 delta;
        float2 position;
        //float3 color;
        float size;
        //int arcID;
        //float arcStr;
    } Ball_t;
    Ball_t *balls;

Please tell me what is the meaning of it,and how to use this keyword. 

What is the meaning of &quot;__attribute__((packed, aligned(4))) &quot;

I write code like this in my [Mac OS X v10.8][1] (Mountain Lion), and when I use &quot;gcc use_new.cpp -o use_new&quot; to compile it, it throws a wrong message like this:

```lang-none
Undefined symbols for architecture x86_64:
  &quot;std::basic_ostream&lt;char, std::char_traits&lt;char&gt; &gt;::operator&lt;&lt;(std::basic_ostream&lt;char, std::char_traits&lt;char&gt; &gt;&amp; (*)(std::basic_ostream&lt;char, std::char_traits&lt;char&gt; &gt;&amp;))&quot;, referenced from:
      _main in ccr2vrRQ.o
  &quot;std::basic_ostream&lt;char, std::char_traits&lt;char&gt; &gt;::operator&lt;&lt;(void const*)&quot;, referenced from:
      _main in ccr2vrRQ.o
  &quot;std::basic_ostream&lt;char, std::char_traits&lt;char&gt; &gt;::operator&lt;&lt;(double)&quot;, referenced from:
      _main in ccr2vrRQ.o
  &quot;std::basic_ostream&lt;char, std::char_traits&lt;char&gt; &gt;::operator&lt;&lt;(int)&quot;, referenced from:
      _main in ccr2vrRQ.o
  &quot;std::basic_ostream&lt;char, std::char_traits&lt;char&gt; &gt;::operator&lt;&lt;(unsigned long)&quot;, referenced from:
      _main in ccr2vrRQ.o
  &quot;std::ios_base::Init::Init()&quot;, referenced from:
      __static_initialization_and_destruction_0(int, int) in ccr2vrRQ.o
  &quot;std::ios_base::Init::~Init()&quot;, referenced from:
      __static_initialization_and_destruction_0(int, int) in ccr2vrRQ.o
  &quot;std::cout&quot;, referenced from:
      _main in ccr2vrRQ.o
  &quot;std::basic_ostream&lt;char, std::char_traits&lt;char&gt; &gt;&amp; std::endl&lt;char, std::char_traits&lt;char&gt; &gt;(std::basic_ostream&lt;char, std::char_traits&lt;char&gt; &gt;&amp;)&quot;, referenced from:
      _main in ccr2vrRQ.o
  &quot;std::basic_ostream&lt;char, std::char_traits&lt;char&gt; &gt;&amp; std::operator&lt;&lt; &lt;std::char_traits&lt;char&gt; &gt;(std::basic_ostream&lt;char, std::char_traits&lt;char&gt; &gt;&amp;, char const*)&quot;, referenced from:
      _main in ccr2vrRQ.o
  &quot;operator delete(void*)&quot;, referenced from:
      _main in ccr2vrRQ.o
  &quot;operator new(unsigned long)&quot;, referenced from:
      _main in ccr2vrRQ.o
ld: symbol(s) not found for architecture x86_64
collect2: error: ld returned 1 exit status
```

And when I use &quot;g++ use_new.cpp -o use_new&quot; it is OK. How can I fix this?

    #include &lt;iostream&gt;

    struct fish
    {
        float weight;
        int id;
        int kind;
    };

    int main()
    {
        using namespace std;
        int* pt = new int;
        *pt = 1001;
        cout &lt;&lt; &quot;int: &quot; &lt;&lt; *pt &lt;&lt; &quot;in location: &quot; &lt;&lt; pt &lt;&lt; endl;
        double* pd = new double;
        *pd = 100000001.0;
        cout &lt;&lt; &quot;double: &quot; &lt;&lt; *pd &lt;&lt; &quot;in location: &quot; &lt;&lt; pd &lt;&lt; endl;
        cout &lt;&lt; &quot;int point pt is length &quot; &lt;&lt; sizeof(*pt) &lt;&lt; endl;
        cout &lt;&lt; &quot;double point pd is length &quot; &lt;&lt; sizeof(*pd) &lt;&lt; endl;
        delete pt;
        delete pd;
        cout &lt;&lt; (int *)&quot;How are you!&quot; &lt;&lt; endl;
        return 0;
    }

  [1]: https://en.wikipedia.org/wiki/OS_X_Mountain_Lion



GCC 4.8 on Mac OS X v10.8 throws &quot;Undefined symbols for architecture x86_64&quot;

I was writing some code today and got a weird compile error, which seems to be caused by initializing member variables in a different order than they were declared.

Example:

    class Test {
        int a;
        int b;
    
    public:
        Test() : b(1), a(2) {
        }
    };
    
    int main() {
        Test test;
        return 0;
    }

Then if I compile it with `-Werror -Wall`:

    $ g++ -Werror -Wall test.cpp
    test.cpp: In constructor ‘Test::Test()’:
    test.cpp:3:9: error: ‘Test::b’ will be initialized after [-Werror=reorder]
    test.cpp:2:9: error:   ‘int Test::a’ [-Werror=reorder]
    test.cpp:6:5: error:   when initialized here [-Werror=reorder]
    cc1plus: all warnings being treated as errors

I realize that `-Wall` is explicitly asking GCC to go over-the-top with warnings, but I assume there&#39;s a reason for all of them. So, how could the order of initializing member variables matter?

Why should I initialize member variables in the order they&#39;re declared in?

Since the [**new ADT preview version (version 21)**][1], they have a new lint warning that tells me the next thing on the manifest file (in the application tag):

&gt; Should explicitly set android:allowBackup to true or false (it&#39;s true by default, and that can have some security implications for the application&#39;s data)

In the [**official website**][1], they&#39;ve written:

&gt; A couple of new checks: you must explicitly decide whether your app allows backups, and a label check. There&#39;s a new command line flag for setting the library path. Many improvements to the incremental lint analysis while editing.

What is this warning? What is the backup feature, and how do I use it?

Also, why does the warning tell me it has security implications? What are the disadvantages and advantages of disabling this feature?

-------------------------------------------------------------------------------

There are two concepts of backup for the manifest:

 - &quot;android:**allowBackup**&quot; allows to backup and restore via adb, as shown [**here**][2]:

&gt; Whether to allow the application to participate in the backup and
&gt; restore infrastructure. If this attribute is set to false, no backup
&gt; or restore of the application will ever be performed, even by a
&gt; full-system backup that would otherwise cause all application data to
&gt; be saved via adb. The default value of this attribute is true.

This is considered a security issue because people could backup your app via [ADB][3] and then get private data of your app into their PC.

However, I think it&#39;s not that of a problem, since most users don&#39;t know what adb is, and if they do, they will also know how to root the device. ADB functions would only work if the device has the debugging feature enabled, and this needs the user to enable it.

So, only users that connect their devices to the PC and enable the debugging feature would be affected. If they have a malicious app on their PC that uses the ADB tools, this could be problematic since the app could read the private storage data.

I think Google should just add a feature that is disabled by default, in the developer category, to allow backup&amp;restore of apps via ADB.

 - &quot;android:**backupAgent**&quot; allows to use the backup and restore feature of the cloud, as shown [**here**][4] and [**here**][5]:

&gt; The name of the class that implement&#39;s the application&#39;s backup agent,
&gt; a subclass of BackupAgent. The attribute value should be a fully
&gt; qualified class name (such as, &quot;com.example.project.MyBackupAgent&quot;).
&gt; However, as a shorthand, if the first character of the name is a
&gt; period (for example, &quot;.MyBackupAgent&quot;), it is appended to the package
&gt; name specified in the &lt;manifest&gt; element. There is no default. The
&gt; name must be specified.

This isn&#39;t a security issue.

  [1]: http://tools.android.com/download/adt-21-preview
  [2]: http://developer.android.com/reference/android/R.attr.html#allowBackup
  [3]: https://en.wikipedia.org/wiki/Android_Debug_Bridge#Android_Debug_Bridge
  [4]: http://developer.android.com/guide/topics/manifest/application-element.html#agent
  [5]: http://developer.android.com/guide/topics/data/backup.html#Basics


What is &quot;android:allowBackup&quot;?

I would like to use a global set of flags for compiling a project, meaning that at my top-level CMakeLists.txt file I have specified:

    ADD_DEFINITIONS ( -Wall -Weffc++ -pedantic -std=c++0x )

However, for a specific file (let&#39;s say &quot;foo.cpp&quot;) in a subdirectory, I want to switch the
compile flags to not apply -Weffc++ (included commercial library I cannot change).  To simplify the situation to use only -Wall, I tried:

     SET_SOURCE_FILES_PROPERTIES( foo.cpp PROPERTIES COMPILE_FLAGS -Wall )
     ADD_EXECUTABLE( foo foo.cpp )
, which did not work.
I also tried

    SET_PROPERTY( SOURCE foo.cpp PROPERTY COMPILE_FLAGS -Wall )
    ADD_EXECUTABLE( foo foo.cpp )
and

    ADD_EXECUTABLE( foo foo.cpp )
    SET_TARGET_PROPERTIES( foo PROPERTIES COMPILE_FLAGS -Wall )
, in which neither worked.

Finally, I tried removing this defintion:

    REMOVE_DEFINITIONS( -Weffc++ )
    ADD_EXECUTABLE( foo foo.cpp )
    ADD_DEFINITIONS( -Weffc++ )
, which also did not work (meaning, I get a lot of style warnings about the commercial library).
(**Note: The warnings ARE suppressed if I DO NOT re-include the -Weffc++ directive after the executable is built.)

I also tried temporarily removing the compile flags:
http://www.cmake.org/pipermail/cmake/2007-June/014614.html
, but that didn&#39;t help.

Is there not an elegant solution to this?

Override compile flags for single files

Consider the following program:

    #include &lt;array&gt;
       
    int main()
    {
      std::array&lt;int, 1&gt; x = { 0 }; // warning!
      x = { { 0 } }; // no warning
      return 0;
    }

The first initialization leads to warnings on gcc 4.7.2...

    main.cpp:5:22: warning: unused variable ‘x’ [-Wunused-variable]

... and clang 3.1

    main.cpp:5:28: warning: suggest braces around initialization of subobject [-Wmissing-braces]
      std::array&lt;int, 1&gt; x = { 0 };

As far as the standard goes, there should be no difference between double or single curly braces, at least in this example.

There are two ways to deal with the warning:

 1. Just turn it off
 2. Fix the code, so the compiler is happy

What do you propose? IMHO, the double curly expression looks somewhat ugly. On the other hand, the warning might detect real problems in more complicated examples. Do you know an example where the warning would have helped you?

Content Type	Original Author	Original Content on Stackoverflow
Question	Saurabh Verma	View Question on Stackoverflow
Solution 1 - C	Daniel Fischer	View Answer on Stackoverflow
Solution 2 - C	orlp	View Answer on Stackoverflow
Solution 3 - C	Zibri	View Answer on Stackoverflow
Solution 4 - C	Andrea Araldo	View Answer on Stackoverflow
Solution 5 - C	Marlab	View Answer on Stackoverflow
Solution 6 - C	Andy Zhang	View Answer on Stackoverflow
Solution 7 - C	Saurabh Verma	View Answer on Stackoverflow

How to compile without warnings being treated as errors?

C Problem Overview

C Solutions

Solution 1 - C

Solution 2 - C

Solution 3 - C

Solution 4 - C

Solution 5 - C

Solution 6 - C

Solution 7 - C

Amazon S3 boto - how to delete folder?

trying to align html button at the center of the my page

Attributions