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POsegmentation fault on a for loop in c
 

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  1. POsegmentation fault on a for loop in c
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    <p>I'm writing a magnetometer sampling function. </p> <p>It goes through the cycle as expected, where samplesPerAxis = 33 and MAX_AXES is 3 and MAX is 999</p> <p>As you can see the segmentation fault occurs after the for loops complete, but the final "end" doesn't print. </p> <pre><code>void createSamplingData(){ int i, indexOfValue, numaxis=0, sampling_value ; printf("%i %i %i\n", magmin[0], magmin[1], magmin[2]); printf("%i %i %i\n", magmax[0], magmax[1], magmax[2]); for (numaxis = 0; numaxis &lt; MAX_AXES; numaxis++){ printf("beginAxis: %i\n", numaxis); sampling_value = magmin[numaxis]; for (i = samplesPerAxis*numaxis ; i &lt; samplesPerAxis*(numaxis+1) ; i++){ indexOfValue = findIndexOfClosestValue(sampling_value, numaxis); printf("%i: %i =&gt; %i\t", i, sampling_value, indexOfValue); MagSamples[i][0] = MagInput[indexOfValue][0]; MagSamples[i][1] = MagInput[indexOfValue][1]; MagSamples[i][2] = MagInput[indexOfValue][2]; printf("%i %i %i\n", MagSamples[i][0], MagSamples[i][1], MagSamples[i][2]); sampling_value = sampling_value + (magmax[numaxis]-magmin[numaxis])/samplesPerAxis; // creates and even range between mag in min in each axis } printf("end axis\n"); } printf("\nend"); } </code></pre> <p>output i get:...</p> <pre><code>beginAxis: 0 0: 32648 =&gt; 263 32648 32760 32916 1: 32656 =&gt; 258 32656 32724 32888 2: 32664 =&gt; 130 32664 32754 32898 ... 29: 32880 =&gt; 488 32880 32774 32804 30: 32888 =&gt; 469 32888 32706 32822 31: 32896 =&gt; 990 32896 32752 32812 32: 32904 =&gt; 973 32904 32808 32844 end axis beginAxis: 1 33: 32624 =&gt; 463 32790 32624 32906 34: 32631 =&gt; 685 32784 32632 32884 35: 32638 =&gt; 652 32756 32638 32926 36: 32645 =&gt; 465 32833 32645 32867 ... 63: 32834 =&gt; 601 32690 32834 32930 64: 32841 =&gt; 597 32689 32841 32923 65: 32848 =&gt; 627 32690 32848 32914 end axis beginAxis: 2 66: 32769 =&gt; 511 32793 32749 32769 67: 32777 =&gt; 512 32785 32755 32777 68: 32785 =&gt; 520 32769 32731 32785 69: 32793 =&gt; 504 32853 32707 32793 ... 98: 33025 =&gt; 86 32805 32775 33025 end axis Segmentation fault: 11 </code></pre> <p>What's going on?</p> <p>EDIT: samplesPerAxis is defined as</p> <pre><code>#define samplesPerAxis 33 </code></pre>
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    1. PO
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      1. PTAnswer
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    1. PTQuestion
    1. USBrian Campbell
    1. USFridiculous
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      1. VTUpMod
    1. COHow is MagSamples defined? I'm guessing the index `samplesPerAxis*(numaxis+1)` is blowing out past the end of allocated memory.
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      1. POsegmentation fault on a for loop in c
      1. USJoe
    2. COAs you can see, it goes from 0-98, just as expected. And "end" gets printed without the trailing "\n"
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      1. POsegmentation fault on a for loop in c
      1. USFridiculous
 

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