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Evaluating string “3*(4+2)” yield int 18 [duplicate]
...NET framework that can evaluate a numeric expression contained in a string and return the result? F.e.:
14 Answers
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C++ equivalent of Java's toString?
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In C++ you can overload operator<< for ostream and your custom class:
class A {
public:
int i;
};
std::ostream& operator<<(std::ostream &strm, const A &a) {
return strm << "A(" << a.i << ")";
}
This way you can output instances ...
Python: changing value in a tuple
...basically two ways of replacing a tuple's element at a given index. Either convert the tuple to a list, replace the element and convert back, or construct a new tuple by concatenation.
In [1]: def replace_at_index1(tup, ix, val):
...: lst = list(tup)
...: lst[ix] = val
...: ret...
Change Circle color of radio button
... of the circle of RadioButton in one of my project , I could not understand which property to set. The background color I am having is black so it gets invisible. I want to set the color of the circle to white.
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In C, how should I read a text file and print all strings
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The simplest way is to read a character, and print it right after reading:
int c;
FILE *file;
file = fopen("test.txt", "r");
if (file) {
while ((c = getc(file)) != EOF)
putchar(c);
fclose(file);
}
c is int above, since EOF is a negative number, an...
How to show a dialog to confirm that the user wishes to exit an Android Activity?
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In Android 2.0+ this would look like:
@Override
public void onBackPressed() {
new AlertDialog.Builder(this)
.setIcon(android.R.drawable.ic_dialog_alert)
.setTitle("Closing Activity")
.setMessage("Are...
How to insert values into C# Dictionary on instantiation?
... LastName="Salimzianova", ID=317}},
{ 113, new StudentName {FirstName="Andy", LastName="Ruth", ID=198}}
};
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Why shouldn't all functions be async by default?
...d now includes not just CPU computations but also some I/O? You'll need to convert the method to async but this would break API and all the callers up the stack would be needed to be updated as well (and they can even be different apps from different vendors). Or you'll need to add async version alo...
Can PostgreSQL index array columns?
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Yes you can index an array, but you have to use the array operators and the GIN-index type.
Example:
CREATE TABLE "Test"("Column1" int[]);
INSERT INTO "Test" VALUES ('{10, 15, 20}');
INSERT INTO "Test" VALUES ('{10, 20, 30}');
CREATE INDEX idx_test on "Test" USING GIN ("Col...
Initialization of all elements of an array to one default value in C++?
...that you used,
int array[100] = {-1};
says "set the first element to -1 and the rest to 0" since all omitted elements are set to 0.
In C++, to set them all to -1, you can use something like std::fill_n (from <algorithm>):
std::fill_n(array, 100, -1);
In portable C, you have to roll your...