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How to check whether a file or directory exists?

...iven file or directory exists func exists(path string) (bool, error) { _, err := os.Stat(path) if err == nil { return true, nil } if os.IsNotExist(err) { return false, nil } return false, err } Edited to add error handling. ...
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NoClassDefFoundError: android.support.v7.internal.view.menu.MenuBuilder

... those conditions and change the app flow: public static boolean isSamsung_4_2_2() { String deviceMan = Build.MANUFACTURER; String deviceRel = Build.VERSION.RELEASE; return "samsung".equalsIgnoreCase(deviceMan) && deviceRel.startsWith("4.2.2"); } Then in the activity's onCreat...
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Modular multiplicative inverse function in Python

... If you happen to be using sympy, then x, _, g = sympy.numbers.igcdex(a, m) does the trick. – Lynn Sep 16 '16 at 18:15 add a comment ...
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What is a “callback” in C and how are they implemented?

...y're implemented using function pointers. Here's an example: void populate_array(int *array, size_t arraySize, int (*getNextValue)(void)) { for (size_t i=0; i<arraySize; i++) array[i] = getNextValue(); } int getNextRandomValue(void) { return rand(); } int main(void) { int m...
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Why does the MongoDB Java driver use a random number generator in a conditional?

... laws it is a trivial observation that this piece of code amounts to if (!_ok && Math.random() <= 0.1) return res; The commit that originally introduced this logic had if (_ok == true) { _logger.log( Level.WARNING , "Server seen down: " + _addr, e ); } else if (Math.random() < 0...
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Android SDK installation doesn't find JDK

... Doesn't work for me on Windows 7 x64. I'm not joking. I set JAVA_HOME and I tried clicking back and next several times, but it's still not working. Neither does running SDK Manager.exe from the archive and I am positive I have JDK 7 installed (even ran the installer again and it told me i...
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Ruby Bundle Symbol not found: _SSLv2_client_method (LoadError)

... ruby-1.9.3-p547 Ruby gets re-installed, but fails in setting up a gemset_pristine for the application because libv8 version 3.16.14.3 failed which was the reason I got to this point in the first place. Vicious frustration circle... update Check your platform version. I have for example Darwin...
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What is the difference between String.Empty and “” (empty string)?

...private hidebysig instance string foo() cil managed { .maxstack 8 L_0000: ldstr "foo" L_0005: ret } .method private hidebysig instance string bar() cil managed { .maxstack 8 L_0000: ldstr "bar" L_0005: ldsfld string [mscorlib]System.String::Empty L_000a: call string [msc...
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Can I call memcpy() and memmove() with “number of bytes” set to zero?

... From the C99 standard (7.21.1/2): Where an argument declared as size_t n specifies the length of the array for a function, n can have the value zero on a call to that function. Unless explicitly stated otherwise in the description of a particular function in this subclause, pointer argume...
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Routes with Dash `-` Instead of Underscore `_` in Ruby on Rails

I want my urls to use dash - instead of underscore _ as word separators. For example controller/my-action instead of controller/my_action . ...