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POFastest base conversion method?
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copied!<p>Right now I'm working on a project which requires an integer to be converted to a base 62 string many times a second. The faster this conversion is completed, the better.</p> <p>The problem is that I'm having a hard time getting my own base conversion methods to be fast <em>and</em> reliable. If I use strings, it's generally reliable and works well, but it's slow. If I use char arrays, it's generally much faster, but it's also very messy, and unreliable. (It produces heap corruption, comparison of strings that should match return a negative, etc.)</p> <p>So what's the fastest and most reliable way of converting from a very large integer to a base 62 key? In the future, I plan on utilizing SIMD model code in my application, so is this operation parallelizable at all?</p> <p>EDIT: This operation is performed several million times a second; as soon as the operation finishes, it begins again as part of a loop, so the faster it runs, the better. The integer being converted is of arbitrary size, and can easily be as large as a 128 bit integer (or larger).</p> <p>EDIT: This is the function I am currently using.</p> <pre><code>char* charset = "0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ"; int charsetLength = (int)(strlen(charset)); //maxChars is an integer specifying the maximum length of the key char* currentKey = new char[maxChars]; void integerToKey(unsigned long long location) { unsigned long long num = location; int i = 0; for(; num > 0; i++) { currentKey[i] = charset[num % (charsetLength)]; num /= charsetLength + 1; } currentKey[i + 1] = '\0'; } </code></pre> <p>I ripped this out of a class that is part of my application, and some of the code is modified so that it makes sense sans its owning class.</p>

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