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<!DOCTYPE concept

  PUBLIC "-//OASIS//DTD DITA Concept//EN" "concept.dtd">

<concept id="GUID-189DA86A-BA77-4314-9597-E3C92B3C82D9" xml:lang="en"><title>Promoting <codeph>char</codeph> in

comparison with RVCT</title><shortdesc>The default <codeph>char</codeph> will be promoted to <codeph>int</codeph> on <codeph>WINSCW</codeph> and <codeph>unsigned</codeph> on

the RVCT compiler. Due to this promotion, comparison c != EOF will not become

true on hardware and it will loop infinite. </shortdesc><prolog><metadata><keywords/></metadata></prolog><conbody>

<p>RVCT treats plain <codeph>char</codeph> type as <codeph>unsigned</codeph> by

default. There is a command line option "<codeph>--signed_chars</codeph>"

that forces RVCT to treat plain char type as a signed char. Using this option,

the example will compile and run the way it is expected to. But

this option must be applied with care, since using the switch universally

may have other ramifications elsewhere in the source base.</p>

<p>The MMP file can be modified as: </p>

<codeblock xml:space="preserve">OPTION armcc  --signed_chars</codeblock>

<p>Example: </p>

<codeblock xml:space="preserve">#include &lt;stdio.h&gt;

int main()

{

  FILE *fp;

  char c;

  fp=fopen("test.txt","w"); 

  fprintf(fp,"%s","ab");

  fclose(fp);

  fp=fopen("test.txt","r"); 

  c=getc(fp);

  while(c != EOF)

  {

     c = getc(fp);

  }

  printf("\nOut of loop");

  fclose(fp);

  getchar();

}

</codeblock>