Databases
StackOverflow2013
Postsdbo
POQuestion about C datatype and constant
 

Note that there are some explanatory texts on larger screens.

plurals
  1. POQuestion about C datatype and constant
    primarykey
    data
    text
    <p>Greetings! I was experimenting with C language till I encountered something very strange. I was not able to explain myself the result shown below.</p> <p><strong>The Code:</strong></p> <pre><code>#include &lt;stdio.h&gt; int main(void) { int num = 4294967295U; printf("%u\n", num); return 0; } </code></pre> <p><strong>The Question:</strong></p> <p>1.) As you see, I created an <code>int</code> which can hold numbers between <em>-2147483648</em> to <em>2147483647</em>.</p> <p>2.) When I assign the value <em>4294967295</em> to this variable, the IDE shows me a warning message during compilation because the variable overflowed.</p> <p>3.) Due to curiosity I added a <em>U (unsigned)</em> behind the number and when I recompiled it, the compiler did not return any warning message.</p> <p>4.) I did further experiments by changing the <em>U (unsigned)</em> to <em>L (long)</em> and <em>LL (long long)</em>. As expected, the warning message still persist for these two but not after I change it to <em>UL (unsigned Long)</em> and <em>ULL (unsigned long long)</em>.</p> <p>5.) Why is this happening?</p> <p><strong>The Warning Message :(For steps 2)</strong></p> <pre><code>warning #2073: Overflow in converting constant expression from 'long long int' to 'int'. </code></pre> <p><strong>The Warning Message:(For steps 4 <em>LL</em> &amp; <em>L</em>)</strong></p> <pre><code>warning #2073: Overflow in converting constant expression from 'long long int' to 'long int'. </code></pre> <p><em>And last, thanks for reading my question, your teachings and advices are much appreciated.</em></p>
    singulars
    1. PO
      singulars
      1. PTAnswer
    1. This table or related slice is empty.
    1. PTQuestion
    1. UScaramel1995
    1. UScaramel1995
    plurals
    1. This table or related slice is empty.
    1. PL
      singulars
      1. LTLinked
    1. This table or related slice is empty.
    1. PO
      singulars
      1. PTAnswer
    2. PO
      singulars
      1. PTAnswer
    1. VO
      singulars
      1. POQuestion about C datatype and constant
      1. This table or related slice is empty.
      1. VTUpMod
    2. VO
      singulars
      1. POQuestion about C datatype and constant
      1. This table or related slice is empty.
      1. VTUpMod
    1. COI think you are looking for a description of promotion rules in C. When I google them, one of the links I find at the top has the title "Integral promotion: It doesn't have to be logical. It's the law". That's a very good summary, perhpas you can find the information you need in that article: http://msmvps.com/blogs/vandooren/archive/2007/10/05/integral-promotion-it-doesn-t-have-to-be-logical-it-s-the-law.aspx
      singulars
      1. POQuestion about C datatype and constant
      1. USPascal Cuoq
    2. COFirst of all, an `int` is only guaranteed to hold values from -32767 to 32767. Your platform very likely offers wider `int`s, but this is unspecified behavior that you cannot rely on.
      singulars
      1. POQuestion about C datatype and constant
      1. USThom Smith
    3. CO@Thom If you are going to be pedantic about it, the range an integral type can hold is **implementation-defined**, which is not the same notion as **unspecified**.
      singulars
      1. POQuestion about C datatype and constant
      1. USPascal Cuoq
 

Querying!

 
Guidance
A row detail

Detail views are divided into sections. All the information in the data section comes from columns in the selected row. The other sections display data from other, related rows.

Related data can be related in a to-one or a to-many fashion. Captions of data related in a to-many fashion link to a list view showing a filtered view of the table.

Try moving around until you find a non-empty to-many entry and click on the label to get to one. You can move back to the root by clicking on the database name in the header.

SQuiL has stopped working due to an internal error.

If you are curious you may find further information in the browser console, which is accessible through the devtools (F12).

Reload