Include [`&lt;stdbool.h&gt;`][1] header
    
    #include &lt;stdbool.h&gt;

    int main(void){
      bool b = false;
    }

Macros `true` and `false` expand to `1` and `0` respectively.

Section `7.16` **Boolean type and values `&lt; stdbool.h &gt;`**

&gt; - 1      The header `&lt;stdbool.h&gt;` deﬁnes four macros.
&gt; - 2      The macro
      - bool
expands to _Bool.
&gt; - 3      The remaining three macros are suitable for use in #if preprocessing directives.  They
are
   - true : which expands to the integer constant 1,
   - false: which expands to the integer constant 0, and
   - __bool_true_false_are_defined
which expands to the integer constant 1.
&gt; - 4      Notwithstanding  the  provisions  of  7.1.3,  a  program  may  undeﬁne  and  perhaps  then
redeﬁne the macros bool, true, and false.

  [1]: http://en.wikipedia.org/wiki/Stdbool.h

Please do check out the answer here on this related thread found on [DaniWeb][1].

extracted and quoted here for convenient reference:-


----------

usage of new keywords in c99
----------------------------

&gt; **_Bool**: C99&#39;s boolean type. Using _Bool directly is only recommended if you&#39;re
&gt; maintaining legacy code that already
&gt; defines macros for bool, true, or
&gt; false. Otherwise, those macros are
&gt; standardized in the `&lt;stdbool.h&gt;`
&gt; header. Include that header and you
&gt; can use bool just like you would in
&gt; C++.

    #include &lt;stdio.h&gt;
    #include &lt;stdbool.h&gt;
     
    int main ( void )
    {
      bool b = true;
     
      if ( b )
        printf ( &quot;Yes\n&quot; );
      else
        printf ( &quot;No\n&quot; );
     
      return 0;
    }


----------


  [1]: http://www.daniweb.com/forums/thread240998.html

While preparing for an interview I stumbled upon this interesting question:

&gt; You&#39;ve been given an array that is sorted and then rotated.
&gt; 
&gt; For example:
&gt; 
&gt; * Let `arr = [1,2,3,4,5]`, which is sorted
&gt; * Rotate it twice to the right to give **`[4,5,1,2,3]`**.
&gt; 
&gt; 
&gt; Now how best can one search in this sorted + rotated array?

One can unrotate the array and then do a binary search. But that is no better than doing a linear search in the input array, as both are worst-case O(N).

Please provide some pointers. I&#39;ve googled a lot on special algorithms for this but couldn&#39;t find any.

I understand C and C++.

Searching in a sorted and rotated array

How do I do I set the syntax highlighting in Vim 7 for python?

I would like to set my own colorschemes, and syntax highlighting for a type of code file.

Syntax highlighting in vim for python

What&#39;s the C99 boolean data type and how to use it?

C99 boolean data type?

<p>What's the C99 boolean data type and how to use it?</p>


Is there something like `startsWith(str_a, str_b)` in the standard C library?

It should take pointers to two strings that end with nullbytes, and tell me whether the first one also appears completely at the beginning of the second one.

Examples:

    &quot;abc&quot;, &quot;abcdef&quot; -&gt; true
    &quot;abcdef&quot;, &quot;abc&quot; -&gt; false
    &quot;abd&quot;, &quot;abdcef&quot; -&gt; true
    &quot;abc&quot;, &quot;abc&quot;    -&gt; true

How to check if a string starts with another string in C?

Find the maximum of two numbers. You should not use if-else or any other comparison operator. I found this question on online bulletin board, so i thought i should ask in StackOverflow

EXAMPLE
Input: 5, 10
Output: 10

I found this solution, can someone help me understand these lines of code

    int getMax(int a, int b) {  
        int c = a - b;  
        int k = (c &gt;&gt; 31) &amp; 0x1;  
        int max = a - k * c;  
        return max;  
    }

Explain this snippet which finds the maximum of two integers without using if-else or any other comparison operator?

I have a struct

    typedef struct {
        int hour;
        int min;
        int sec;
    } counter_t;

And in the code, I&#39;d like to initialize instances of this struct without explicitly initializing each member variable. That is, I&#39;d like to do something like:

    counter_t counter;
    counter = {10,30,47}; //doesn&#39;t work

for 10:30:47


rather than

    counter.hour = 10;
    counter.min = 30;
    counter.sec = 47;

Don&#39;t recall syntax for this, and didn&#39;t immediately find a way to do this from Googling.

Thanks!


How to assign a C struct inline?

I&#39;m trying to write a number to two decimal places using `printf()` as follows:

    #include &lt;cstdio&gt;
    int main()
    {
      printf(&quot;When this number: %d is assigned to 2 dp, it will be: 2%f &quot;, 94.9456, 94.9456);
      return 0;
    }

When I run the program, I get the following output:

&lt;!-- language: lang-none --&gt;

    # ./printf
    When this number: -1243822529 is assigned to 2 db, it will be: 2-0.000000


Why is that?

Thanks.





Two decimal places using printf( )

Is there a way to check if the type of a variable in python is a `string`, like:

    isinstance(x,int);

for integer values?



How to check if type of a variable is string?

What&#39;s the difference between the `text` data type and the `character varying` (`varchar`) data types?

According to [the documentation][1]

&gt; If character varying is used without length specifier, the type accepts strings of any size. The latter is a PostgreSQL extension.

and

&gt; In addition, PostgreSQL provides the text type, which stores strings of any length. Although the type text is not in the SQL standard, several other SQL database management systems have it as well.

So what&#39;s the difference?

  [1]: http://www.postgresql.org/docs/8.0/interactive/datatype-character.html

Difference between text and varchar (character varying)

I just stumbled upon something I&#39;ve never seen before. In the source of Backbone.js&#39;s example TODO application ([Backbone TODO Example][1]) they had their templates inside a `&lt;script type = &quot;text/template&quot;&gt;&lt;/script&gt;`, which contained code that looks like something out of PHP but with JavaScript tags.

Can someone explain this to me? Is this legit?


  [1]: http://documentcloud.github.com/backbone/examples/todos/index.html

Explanation of &lt;script type = &quot;text/template&quot;&gt; ... &lt;/script&gt;

***Scala***

Where can differences between a class and a type be observed in Scala and why is this distinction important?

Is it only a consideration from the language design point-of-view or has it &quot;practical&quot; impact when programming Scala?

Or is it fundamental to &quot;securing the boundaries&quot; of the type system (`Nothing`, `Null` come to my mind)?

***Java***

How many of the considerations/differences/problems mentioned above can also be recognized in Java?


----------

(See [What is the difference between Type and Class?][1] as a language-agnostic introduction.)




  [1]: https://stackoverflow.com/questions/468145/what-is-the-difference-between-type-and-class

What is the difference between a class and a type in Scala (and Java)?

So, normally `ArrayList.toArray()` would return a type of `Object[]`....but supposed it&#39;s an 
`Arraylist` of object `Custom`, how do I make `toArray()` to return a type of `Custom[]` rather than `Object[]`?


make arrayList.toArray() return more specific types

Today I was playing with PHP, and I discovered that the string values &quot;true&quot; and &quot;false&quot; are not correctly parsed to boolean in a condition, for example considering the following function:

    function isBoolean($value) {
       if ($value) {
          return true;
       } else {
          return false;
       }
    }

If I execute:

    isBoolean(&quot;true&quot;) // Returns true
    isBoolean(&quot;&quot;) // Returns false
    isBoolean(&quot;false&quot;) // Returns true, instead of false
    isBoolean(&quot;asd&quot;) // Returns true, instead of false

It only seems to work with &quot;1&quot; and &quot;0&quot; values:

    isBoolean(&quot;1&quot;) // Returns true
    isBoolean(&quot;0&quot;) // Returns false

Is there a native function in PHP to parse &quot;true&quot; and &quot;false&quot; strings into boolean?




Parsing a string into a boolean value in PHP

I can&#39;t find an answer in the standard documentation. Does the C++ language standard require `sizeof(bool)` to always be 1 (for 1 byte), or is this size implementation-defined?

Is sizeof(bool) defined in the C++ language standard?

The following code doesn&#39;t print out anything:

    $bool_val = (bool)false;
    echo $bool_val;

But the following code prints `1`:

    $bool_val = (bool)true;
    echo $bool_val;

Is there a better way to print `0` or `false` when `$bool_val` is `false` than adding an `if` statement?

PHP - Get bool to echo false when false

I have a jQuery function tied to my submit button like this:

    $(function () {
        $(&#39;#signupform&#39;).submit(function () {
            alert(&#39;test&#39;);
        });
    });

However, it fires whether or not the form is valid. My model is decorated with various DataAnnotations and the client-side validation is working well, but I only want that jQuery function to fire if the form has been validated. How do I accomplish that?

**EDIT:** To clarify, I&#39;m using MVC DataAnnotations + jQuery&#39;s unobtrusive javascript to handle the client-side validation. I do not have my own javascript validation routines written. The built in jQuery validation is doing a great job of validating the form, but I just need to know how to get the results of that validation into a boolean value within my own function.

How to fire jQuery function only if form is valid

I tried running this piece of code:

    path = &#39;/bla/bla/bla&#39;

    if path is True:
        print &quot;True&quot;
    else:
        print &quot;False&quot;

And it prints **False**. I thought Python treats anything with value as **True**. Why is this happening?


&#39;True&#39; and &#39;False&#39; in Python

How portable is this conversion. Can I be sure that both assertions pass?

    int x = 4&lt;5;
    assert(x==1);
    
    x = 4&gt;5;
    assert(x==0);

Don&#39;t ask why. I know that it is ugly. Thank you.

bool to int conversion

There is a [well-known][1] [problem][2] with empty args for variadic macros in C99.

example:

    #define FOO(...)       printf(__VA_ARGS__)
    #define BAR(fmt, ...)  printf(fmt, __VA_ARGS__)

    FOO(&quot;this works fine&quot;);
    BAR(&quot;this breaks!&quot;);

The use of `BAR()` above is indeed incorrect according to the C99 standard, since it will expand to:

    printf(&quot;this breaks!&quot;,);

Note the trailing comma - not workable.

Some compilers (eg: Visual Studio 2010) will quietly get rid of that trailing comma for you. Other compilers (eg: GCC) support putting `##` in front of `__VA_ARGS__`, like so:

    #define BAR(fmt, ...)  printf(fmt, ##__VA_ARGS__)

But is there a standards-compliant way to get this behavior?
Perhaps using multiple macros?

Right now, the `##` version seems fairly well-supported (at least on my platforms), but I&#39;d really rather use a standards-compliant solution.

Pre-emptive: I know I could just write a small function. I&#39;m trying to do this using macros.

__Edit__: Here is an example (though simple) of why I would want to use BAR():

    #define BAR(fmt, ...)  printf(fmt &quot;\n&quot;, ##__VA_ARGS__)
    
    BAR(&quot;here is a log message&quot;);
    BAR(&quot;here is a log message with a param: %d&quot;, 42);

This automatically adds a newline to my BAR() logging statements, assuming `fmt` is always a double-quoted C-string. It does NOT print the newline as a separate printf(), which is advantageous if the logging is line-buffered and coming from multiple sources asynchronously.



  [1]: https://stackoverflow.com/questions/4054085/gcc-appending-to-va-args
  [2]: http://gcc.gnu.org/onlinedocs/cpp/Variadic-Macros.html

Standard alternative to GCC&#39;s ##__VA_ARGS__ trick?

When I try to build this code

    inline void f() {}
    
    int main()
    {
        f();
    }

using the command line

    gcc -std=c99 -o a a.c

I get a linker error (undefined reference to `f`).  The error vanishes if I use `static inline` or `extern inline` instead of just `inline`, or if I compile with `-O` (so the function is actually inlined).

This behaviour seems to be defined in paragraph 6.7.4 (6) of the C99 standard:
&gt; If all of the file scope declarations for a function in a translation unit include the `inline` function specifier without `extern`, then the definition in that translation unit is an inline definition. An inline definition does not provide an external definition for the function, and does not forbid an external definition in another translation unit. An inline definition provides an alternative to an external definition, which a translator may use to implement any call to the function in the same translation unit. It is unspecified whether a call to the function uses the inline definition or the external definition.

If I understand all this correctly, a compilation unit with a function defined `inline` as in the above example only compiles consistently if there is also an external function with the same name, and I never know if my own function or the external function is called.

Isn&#39;t this behaviour completely daft? Is it ever useful to define a function `inline` without `static` or `extern` in C99?  Am I missing something?

## Summary of answers

Of course I was missing something, and the behaviour isn&#39;t daft. :)

As [Nemo explains](https://stackoverflow.com/questions/6312597/is-inline-without-static-or-extern-ever-useful-in-c99/6312813#6312813), the idea is to put the *definition* of the function

    inline void f() {}

in the header file and only a *declaration*

    extern inline void f();

in the corresponding .c file.  Only the `extern` declaration triggers the generation of externally visible binary code.  And there is indeed no use of `inline` in a .c file -- it&#39;s only useful in headers.

As the [rationale of the C99 committee quoted in Jonathan&#39;s answer](https://stackoverflow.com/questions/6312597/is-inline-without-static-or-extern-ever-useful-in-c99/6312854#6312854) explicates, `inline` is all about compiler optimisations that require the definition of a function to be visible at the site of a call.  This can only be achieved by putting the definition in the header, and of course a definition in a header must not emit code every time it is seen by the compiler.  But since the compiler is not forced to actually inline a function, an external definition must exist somewhere.

Is &quot;inline&quot; without &quot;static&quot; or &quot;extern&quot; ever useful in C99?

    static struct fuse_oprations hello_oper = {
      .getattr = hello_getattr,
      .readdir = hello_readdir,
      .open    = hello_open,
      .read    = hello_read,
    };

I don&#39;t understand this C syntax well. I can&#39;t even search because I don&#39;t know the syntax&#39;s name. What&#39;s that?

What does dot (.) mean in a struct initializer?

Is the difference of two non-void pointer variables defined (per C99 and/or C++98) if they are both `NULL` valued?

For instance, say I have a buffer structure that looks like this:

    struct buf {
      char *buf;
      char *pwrite;
      char *pread;
    } ex;

Say, `ex.buf` points to an array or some malloc&#39;ed memory. If my code always ensures that `pwrite` and `pread` point within that array or one past it, then I am fairly confident that `ex.pwrite - ex.pread` will always be defined. However, what if `pwrite` and `pread` are both NULL. Can I just expect subtracting the two is defined as `(ptrdiff_t)0` or does strictly compliant code need to test the pointers for NULL? Note that the only case I am interested in is when *both* pointers are NULL (which represents a buffer not initialized case). The reason has to do with a fully compliant &quot;available&quot; function given the preceding assumptions are met:

    size_t buf_avail(const struct s_buf *b)
    {     
        return b-&gt;pwrite - b-&gt;pread;
    }


Content Type	Original Author	Original Content on Stackoverflow
Question	eonil	View Question on Stackoverflow
Solution 1 - C	Prasoon Saurav	View Answer on Stackoverflow
Solution 2 - C	evandrix	View Answer on Stackoverflow

C99 boolean data type?

C Problem Overview

C Solutions

Solution 1 - C

Solution 2 - C

usage of new keywords in c99

Syntax highlighting in vim for python

Searching in a sorted and rotated array

Attributions