Further, note that C does not retain any type information into runtime. This means that, even if, hypothetically, there was a type comparison extension, it would only work properly when the types are known at compile time (ie, it wouldn't work to test whether two void * point to the same type of data). As for typeof: First, typeof is a GCC ...

Is there any way that I can discover the type of a variable automatically in C, either through some mechanism within the program itself, or--more likely--through a pre-compilation script that uses the compiler's passes up to the point where it has parsed the variables and assigned them their types? I'm looking for general suggestions about this.

2023年6月15日 · Assigning an scalar type (arithmetic types and pointer types) to _Bool or bool, if the scalar value is equal to 0 or compares to 0 it will be 0, otherwise the result is 1: _Bool x = 9; 9 is converted to 1 when assigned to x.

2024年3月9日 · Which shows that the constant type is based on the literal assigned to it, and integer literals without a suffix always customarily follow int > long int > long long int (and a character literal is also an int in C, but not C++). The enum type, however, appears to be the smallest type that can represent all constants defined in the enum (and ...

2012年7月3日 · Usually, wanting to find the type of a variable in C++ is the wrong question. It tends to be something you carry along from procedural languages like for instance C or Pascal. If you want to code different behaviours depending on type, try to learn about e.g. function overloading and object inheritance. This won't make immediate sense on your ...

2009年10月22日 · In C99 the native type is actually called _Bool, while bool is a standard library macro defined in stdbool.h (which expectedly resolves to _Bool). Objects of type _Bool hold either 0 or 1, while true and false are also macros from stdbool.h. Note, BTW, that this implies that C preprocessor will interpret #if true as #if 0 unless stdbool.h is

2014年9月10日 · This increments Flash_ptr by 0x200 elements, but since Flash_ptr is of type unsigned char * then this just translates to an increment of 0x200 bytes. In order to make this part of a loop and check for an upper bound you would do something like this:

c_info[i] in low-level words means: Take the pointer c_info, add i times the size of the type it points to (so it points to the i-th entry) and dereference that address. This means, that c_info[i] actually is the Employee at the i-th index (but not a pointer). Then …

This solved the issue of being able to declare the classes in eachother, but I'm now left with an "Incomplete type error" when trying to access a passed reference to the object. There seem to be a few similar examples around, though often mixed with more complex code and hard to narrow down to the basics.

The compiler will not protect you from these events, except maybe through a warning that is generated at compile time. Slicing can also occur when a derived type is implicitly converted to a base type (by value). For conversions that can be downright dangerous (e.g., from a base to a derived type), the C++ standard requires an explicit cast.