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POUsing int for character types when comparing with EOF
 

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    <p>Quoting from Kernighan and Ritchie's 'The C Programming Language' Page 16 - </p> <pre><code>#include&lt;stdio.h&gt; main() { int c; c = getchar(); while(c!=EOF) { putchar(c); c = getchar(); } getchar(); return 0; } </code></pre> <p>"The type <code>char</code> is specifically meant for storing such character data, but any integer type can be used. We used <code>int</code> for a subtle but important reason. The problem is distinguishing the end of the input from valid data. The solution is that <code>getchar</code> returns a distinctive value when there is no more input, a value that cannot be confused with any real character. This value is called <code>EOF</code>, for "end of file". We must declare <code>c</code> to be a type big enough to hold any value that <code>getchar</code> returns. We can't use <code>char</code> since <code>c</code> must be big enough to hold <code>EOF</code> in addition to any possible <code>char</code>. Therefore we use <code>int</code>.".</p> <p>I looked up in stdio.h, it says <code>#define EOF (-1)</code></p> <p>The book conclusively states that <code>char</code> cannot be used whereas this program "works just fine" (See EDIT) with <code>c</code> as <code>char</code> data type as well. What is going on? Can anyone explain in terms of bits and signed values? </p> <p><strong>EDIT:</strong><br> As Oli mentioned in the answer, the program cannot distinguish between <code>EOF</code> and <code>255</code>. So it will not work fine. I want to know what's happening - Are you saying that when we do the comparison c!=EOF, the EOF value gets cast to a char value = 255 (11111111 in binary; i.e. the bits 0 through 7 of EOF when written in 2's complement notation)? </p>
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    1. CODefine "works just fine". What inputs have you tried?
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    2. CO@CharlesBailey - I am aware that the program will not work fine with 255 input as Oli mentioned in the answer below. I am trying to explore what is happening here. EDITing the question accordingly.
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