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    <p><code>fgetc()</code> returns <code>unsigned char</code> and EOF. EOF is always &lt; 0. If the system's <code>char</code> is <code>signed</code> or <code>unsigned</code>, it makes no difference.</p> <p>C11dr 7.21.7.1 2</p> <p>If the end-of-file indicator for the input stream pointed to by stream is not set and a next character is present, the fgetc function obtains that character as an <strong>unsigned char</strong> converted to an int and advances the associated file position indicator for the stream (if defined).</p> <p>The concern I have about is that is looks to be 2's compliment dependent and implying the range of <code>unsigned char</code> and <code>char</code> are both just as wide. Both of these assumptions are certainly <em>nearly</em> always true today. </p> <p><code>buf = (char) ((c &gt; CHAR_MAX) ? (c - (UCHAR_MAX + 1)) : c);</code></p> <p>[Edit per OP comment]<br> Let's assume <code>fgetc()</code> returns no more different characters than stuff-able in the range <code>CHAR_MIN</code> to <code>CHAR_MAX</code>, then <code>(c - (UCHAR_MAX + 1))</code> would be more portable is replaced with <code>(c - CHAR_MAX + CHAR_MIN)</code>. We do not know <code>(c - (UCHAR_MAX + 1))</code> is in range when <code>c is CHAR_MAX + 1</code>.</p> <p>A system <em>could</em> exist that has a <code>signed char</code> range of -127 to +127 and an <code>unsigned char</code> range 0 to 255. (5.2.4.2.1), but as <code>fgetc()</code> gets a <em>character</em>, it seems to have all be <code>unsigned char</code> <strong>or</strong> all ready limited itself to the smaller <code>signed char</code> range, before converting to <code>unsigned char</code> and return that value to the user. OTOH, if <code>fgetc()</code> returned 256 different characters, conversion to a narrow ranged <code>signed char</code> would not be portable regardless of formula.</p>
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    1. POBest way to portably assign the result of fgetc() to a char in C
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    1. COYou are absolutely correct about the nature of fgetc()'s return value, but that wasn't my question. The crux is that converting an integer value to a signed integer type produces implementation-defined behavior if the value is outside the range of the target type (or please correct me if I'm wrong). If my platform uses 8-bit signed chars, and the character I read is a British pound sign encoded in ISO-8859-1, then fgetc() will return an int value (positive) 0xA3, which is outside the range of char. Isn't that a problem?
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      1. USJohn Bollinger
    2. COIn practice, it is not a problem. Sorting out where the standard says it isn't may take a bit of effort. Every implementation defines the conversion from 0xA3 to `signed char` as a bitwise copy of the lowest 8 bits of the `int` value (and an implementation which did not would probably not be used).
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      1. USJonathan Leffler
    3. CO@chux: upon reflection I think the discussion of character codes vs. signed default chars is a false trail. As in many places they do, and as C itself does, the docs you quoted conflate "character" and "byte". The question might better be couched in terms of how multiple fgetc() calls can portably be substituted for one fread() call when the target buffer is of type default char (as may be needed as input to some other function that will treat it as binary data).
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