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POQT socket read losing bytes
 

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    <p>I'm trying to work with length-preceded TCP messages using Qt. I have following method:</p> <pre><code>QByteArray con::read() { QByteArray s; s = _pSocket-&gt;read(4); if (s.length() == 4) { int size = char_to_int32(s); s = _pSocket-&gt;read(size); } return s; } </code></pre> <p>Well, it does not work. Looks like I lose all data after reading first 4 bytes: the first read works fine, but <code>read(size)</code> returns nothing. Is there a way to solve this?</p> <p>The char_to_int32 is:</p> <pre><code>int char_to_int32(QByteArray s) { int size = 0; size |= (s.at(0) &lt;&lt; 24); size |= (s.at(1) &lt;&lt; 16); size |= (s.at(2) &lt;&lt; 8); size |= (s.at(3)); return size; } </code></pre> <p><strong>EDIT :</strong></p> <p>The sending function (plain C):</p> <pre><code>int send(int connfd, const unsigned char* message, unsigned int size) { int c; unsigned char* bytes = (unsigned char*) malloc(4 + size); int32_to_char(size, bytes); // converts message size to 4 bytes memcpy(bytes + 4, message, size); c = write(connfd, bytes, 4 + size); free(bytes); if (c &lt;= 0) return -1; else return 0; } </code></pre> <p>By the way, when I call _pSocket->readAll(), the entire packet is read, including 4-byte size and message itself.</p> <p><strong>EDIT :</strong></p> <pre><code>void int32_to_char(uint32_t in, char* bytes) { bytes[0] = (in &gt;&gt; 24) &amp; 0xFF; bytes[1] = (in &gt;&gt; 16) &amp; 0xFF; bytes[2] = (in &gt;&gt; 8) &amp; 0xFF; bytes[3] = in &amp; 0xFF; return; } </code></pre>
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    1. COCould you provide the `char_to_int32` function definition?
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      1. USmfontanini
    2. COwhat is the size? are you sure it's 32 bit signed int?
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      1. USNot_a_Golfer
    3. COTry to print "size" value before using it in the read(). I bet the problem is there
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      1. USnax83
 

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