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POHow to initialize an array in c?
 

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  1. POHow to initialize an array in c?
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    <p>I have a function that should initialize an array of length 3 and return it. See the code below. It's working so far but only for certain colors. I recognized a bug in my code when I tried to write violet. I got a trailing orange element when I write violet. Why is that and how can I fix it? I have more color arrays like this defined and some of them seem to "leak" colors. I guess there's something wrong how I initialize the arrays. Hope someone can shed some light into this.</p> <pre><code>#define LEDS 64 struct array{ unsigned char hex[LEDS * 3]; }; struct array init_array(int r, int g, int b) { int i; struct array z; //GRB data, 3 bits for each color for(i = 0; i &lt; sizeof(struct array) / sizeof(char); i++) { if(i == 0) z.hex[i] = g | 128; else if(i==1) z.hex[i] = r | 128; else z.hex[i] = b | 128; } return z; } ... struct array orange; struct array violet; ... violet=init_array(173, 141, 171); orange=init_array(192, 145, 128); while(1) { for(i=0; i&lt;=LEDS; i++) { transfer(fd, violet.hex, sizeof (violet.hex)); } for(i=0; i&lt;=LEDS; i++) { transfer(fd, orange.hex, sizeof (orange.hex)); } } </code></pre> <p>That's the transfer function:</p> <pre><code>void transfer(int fd, char* tx, uint32_t len) { int ret; uint8_t rx[sizeof (&amp;tx)] = {0,}; // RX buffer struct spi_ioc_transfer data = { .tx_buf = (unsigned long) tx, .rx_buf = (unsigned long) rx, .len = len, .delay_usecs = delay, .speed_hz = speed, .bits_per_word = bits, .cs_change = 0, }; ret = ioctl(fd, SPI_IOC_MESSAGE(1), &amp;data); if (ret &lt; 1) pabort("can't send spi message"); usleep(50); } </code></pre>
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    1. COWhat's `transfer()`?
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      1. POHow to initialize an array in c?
      1. USHAL
    2. COI think you meant 3 bytes for each LED, so 8 bits for each color, isn't it? If that's the case, you should change your if's inside init_array to check for multiples of 1, 2 and 3. The way you are doing, you are treating the first led (the first 3 bytes) correctly (as far as I can understand your algorithm) and then all leds incorrectly.
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    3. CO@nos in some color space interpretation, yes.
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      1. USXephon
 

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