casting
warning: ISO C++ forbids variable length array
Array in C++ must have a size defined at compile-time. If you want variable length array, use std::vector instead. In your case, I would use template for Matrix Size and have different implementation for different matrix size (unless I misunderstood your intentions). Since I did not defined the generic template, using any other value than 2 or … Read more
Change column type in pandas
You have four main options for converting types in pandas: to_numeric() – provides functionality to safely convert non-numeric types (e.g. strings) to a suitable numeric type. (See also to_datetime() and to_timedelta().) astype() – convert (almost) any type to (almost) any other type (even if it’s not necessarily sensible to do so). Also allows you to convert to categorial types (very useful). infer_objects() – … Read more
dynamic_cast and static_cast in C++
Here’s a rundown on static_cast<> and dynamic_cast<> specifically as they pertain to pointers. This is just a 101-level rundown, it does not cover all the intricacies. static_cast< Type* >(ptr) This takes the pointer in ptr and tries to safely cast it to a pointer of type Type*. This cast is done at compile time. It will only perform the cast if the types … Read more
warning: assignment makes integer from pointer without a cast
When I declare a char * to a fixed string and reuse the pointer to point to another string I tried to recast the pointer but no success.
How do I convert a string to a number in PHP?
You don’t typically need to do this, since PHP will coerce the type for you in most circumstances. For situations where you do want to explicitly convert the type, cast it:
warning: assignment makes integer from pointer without a cast
When you write the statement the compiler sees the constant string “abcdefghijklmnop” like an array. Imagine you had written the following code instead: Now, it’s a bit clearer what is going on. The left-hand side, *src, refers to a char (since src is of type pointer-to-char) whereas the right-hand side, otherstring, refers to a pointer. This isn’t strictly forbidden because you may want … Read more
Explanation of ClassCastException in Java
Straight from the API Specifications for the ClassCastException: Thrown to indicate that the code has attempted to cast an object to a subclass of which it is not an instance. So, for example, when one tries to cast an Integer to a String, String is not an subclass of Integer, so a ClassCastException will be thrown.
Converting double to integer in Java
is there a possibility that casting a double created via Math.round() will still result in a truncated down number No, round() will always round your double to the correct value, and then, it will be cast to an long which will truncate any decimal places. But after rounding, there will not be any fractional parts remaining. Here are the docs from Math.round(double): … Read more
Why unsigned int 0xFFFFFFFF is equal to int -1?
C and C++ can run on many different architectures, and machine types. Consequently, they can have different representations of numbers: Two’s complement, and Ones’ complement being the most common. In general you should not rely on a particular representation in your program. For unsigned integer types (size_t being one of those), the C standard (and the … Read more