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C++ Standards Support in GCC
GCC supports different dialects of C++, corresponding to the multiple published ISO standards. Which standard it implements can be selected using the -std= command-line option.C++98 − GCC has full support for the 1998 C++ standard as modified in 2003 and renamed to C++03 and some later defect reports.C++11 − GCC 4.8.1 was the first complete implementation of the 2011 C++ standard, previously known as C++0x.C++14 − GCC has full support for the latest revision of the C++ standard, which was published in 2014.C++17 − GCC has experimental support for the next revision of the C++ standard, which is expected to ...
Read MoreWhat are Aggregates and PODs in C++?
POD is an acronym in C++ that means plain old data. It is a class/struct that ONLY has member variables and no methods, constructors, destructors, virtual functions, etc. For example, Example#include using namespace std; // POD struct MyStruct { int key; string data; }; int main() { struct MyStruct s; s.key = 1; s.data = "hello"; return 0; }The struct MyStruct has no user defined ctor, dtor, etc and hence is a POD.An aggregate is an array or a class with no user-declared constructors, no private or protected non-static data members, no base ...
Read MoreC++ vs C++0x vs C++11 vs C++98
C++98 was the first edition of the C++ standard. It had defined all the basic language constructs, the STL, and the standard library.C++03 was the next revision to this standard. This was majorly a considered a bugfix for the standard as it corrected 92 core language defect reports, 125 library defect reports, and included only one new language feature: value initialization.C++0x was the name of the work in progress that was expected to complete by 2008-09 but finally completed in 2011.C++11 was the modern C++ standard published in 2011. This brought many major extensions and improvements to the existing language. ...
Read MoreHow do I declare a two-dimensional array in C++ using new?
A dynamic 2D array is basically an array of pointers to arrays. So you first need to initialize the array of pointers to pointers and then initialize each 1d array in a loop.example#include using namespace std; int main() { int rows = 3, cols = 4; int** arr = new int*[rows]; for(int i = 0; i < rows; ++i) arr[i] = new int[cols]; return 0; } This will create an 2D array of size 3x4. Be vary of clearing the memory in such cases as you'll need to delete the memory in the ...
Read MoreDifference between const int*, const int * const, and int const * in C/C++?
The above symbols mean the following −int* - Pointer to int. This one is pretty obvious. int const * - Pointer to const int. int * const - Const pointer to int int const * const - Const pointer to const intAlso note that −const int * And int const * are the same. const int * const And int const * const are the same.If you ever face confusion in reading such symbols, remember the Spiral rule: Start from the name of the variable and move clockwise to the next pointer or type. Repeat until expression ends.
Read MoreTokenize a string in C++?
First way is using a stringstream to read words seperated by spaces. This is a little limited but does the task fairly well if you provide the proper checks. example#include #include #include using namespace std; int main() { string str("Hello from the dark side"); string tmp; // A string to store the word on each iteration. stringstream str_strm(str); vector words; // Create vector to hold our words while (str_strm >> tmp) { // Provide proper checks here for tmp like if empty // ...
Read MoreHow to read and parse CSV files in C++?
You should really be using a library to parsing CSV files in C++ as there are many cases that you can miss if you read files on your own. The boost library for C++ provides a really nice set of tools for reading CSV files. For example, example#include vector parseCSVLine(string line){ using namespace boost; std::vector vec; // Tokenizes the input string tokenizer tk(line, escaped_list_separator ('', ', ', '"')); for (auto i = tk.begin(); i!=tk.end(); ++i) ...
Read MoreHow do you set, clear, and toggle a bit in C/C++?
You can set clear and toggle bits using bitwise operators in C, C++, Python, and all other programming languages that support these operations. You also need to use the bitshift operator to get the bit to the right place.Setting a bitTo set a bit, we'll need to use the bitwise OR operator −Example#include using namespace std; int main() { int i = 0, n; // Enter bit to be set: cin >> n; i |= (1 > n; i ^= (1
Read MoreWhen can I use a forward declaration C/C++?
Forward declaration lets the code following the declaration know that there is are classes with the name Person. This satisfies the compiler when it sees these names used. Later the linker will find the definition of the classes. exampleClass Person; void myFunc(Person p1) { // ... } Class Person { // Class definition here };So in this case when compiler encounters myFunc, it'll know that its going to encounter this class somewhere down in the code. This can be used in cases where code using the class is placed/included before the code containing the class definition.
Read MoreWhy is not sizeof for a struct equal to the sum of sizeof of each member in C/C++?
The difference between sizeof for a struct and the sum of sizeof of each member of that struct is due to byte padding and alignment. Every data type in C/C++ has a alignment requirement. A processor will have processing word length of its architecture. On a 32 bit machine, the processing word size will be 4 bytes or 32 bits. For example, If you have the struct −Example#include using namespace std; struct X { char b[3]; int c; }; int main() { char b[3]; int c; int total = sizeof(b) + sizeof(c); cout
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