Simple C++ kickoff
Multi-paradigm: procedural, functional, object-oriented, generic, modular
Static, nominative, partially inferred
Filename extensions: .C, .cc, .cpp, .cxx, .c++, .h, .H, .hh, .hpp, .hxx, .h++
First appeared 1985;
Stable release C++20 (ISO/IEC 14882:2020) / 15 December 2020;
Preview release C++23 / 15 December 2020;
- gcc is both a C and C++ compiler. It will look at the file's extension and process accordingly. g++ is only a wrapper that calls gcc g++ is installed with the gcc package in Arch
Compiler: GNU Compiler-Collection:
pacman -S gcc
Arch Linux group base-devel might be an overkill.
https://archlinux.org/groups/x86_64/base-devel/
sudo pacman -S base-devel
ms-vscode.cpptools
The Structure of a Basic C++ Program
// main.cpp
#include <cstdio>
int main(){
printf("Hello, world!");
return 0;
}make first
or
g++ -o first first.cpp
or
gcc file.C # uppercase .C (or .cpp) will process as C++ gcc file.c # lowercase .c will process as C
Beside gcc, there are some more compilers like clang https://www.stroustrup.com/compilers.html https://en.wikipedia.org/wiki/List_of_compilers#C++_compilers
The preprocessor performs basic source code manipulation.
For example, #include <cstdio> is a directive that instructs the preprocessor to include information about the cstdio library directly into your program’s source code. When the preprocessor finishes processing a source file, it produces a single translation unit. Each translation unit is then passed to the compiler for further processing.
The compiler reads a translation unit and generates an object file.
Object files contain an intermediate format called object code. These files con- tain data and instructions in an intermediate format that most humans wouldn’t understand. Compilers work on one translation unit at a time, so each translation unit corresponds to a single object file.
The linker generates programs from object files.
Linkers are also responsible for finding the libraries you’ve included within your source code. When you compile first.cpp, for example, the linker will find the cstdio library and include everything your program needs to use the printf function. Note that the cstdio header is dis tinct from the cstdio library. The header contains information about how to use the library.
We don't use any scaffolding tools here. You can write your own with Bash.
C++ is an strongly typed, object-oriented language.
int aNumber;
aNumber = 14;
comparison operators
int main() {
int x = 0;
421 == x; // Equality
421 != x; // Inequality
1001 > x; // Greater than
123 >= x; // Greater than or equal to
-101 < x; // Less than
-99 <= x; // Less than or equal to
}An if statement contains a Boolean expression and one or more nested statements.
if (boolean-expression) statement
if (boolean-expression) {
statement1;
statement2;
--snip--
}if (boolean-expression-1) statement-1
else if (boolean-expression-2) statement-2
else statement-3Functions are blocks of code that accept any number of input objects called parameters or arguments and can return output objects to their callers.
Calling / invoking Functions
printf , which has a lineage that traces back to C
Another option is cout , which is part of the C++ standard library’s iostream library.
// This comment is on its own line
/*
* This is a comment
* That lives on multiple lines
* Don't forget to close
*/Fundamental Types
integer, floating-point, character, Boolean, byte , size_t , and void . Some refer to fundamental types as primitive or built-in types because they’re part of the core language and almost always available to you.
int
float
character
boolean
std::byte
size_t
The type size_t is a C type in the header, but it’s identical to the C++ version, which resides in the std namespace. Occasionally, you’ll see the (technically correct) construction std::size_t instead.
sizeof The unary operator sizeof takes a type operand and returns the size (in bytes) of that type. The sizeof operator always returns a size_t. For example, sizeof(float) returns the number of bytes of storage a float takes.
#include <cstdio>
struct Book {
char name[256]; u
int year; v
int pages; w
bool hardcover; x
};
int main() {
Book neuromancer;
neuromancer.pages = 271;
printf("Neuromancer has %d pages.", neuromancer.pages);
}
Methods are member functions. Access Controls private
The class Keyword You can replace the struct keyword with the class keyword, which declares members private by default. Aside from default access control, classes declared with the struct and class keywords are the same.
Constructors are special methods with special declarations.
struct ClockOfTheLongNow {
ClockOfTheLongNow() {
year = 2019;
}
--snip--
};
int main() {
ClockOfTheLongNow clock;
printf("Default year: %d", clock.get_year()); x
}Destructor cleanup function The destructor is invoked before an object is destroyed. Destructors are almost never called explic- itly: the compiler will ensure that each object’s destructor is called as appropriate.
struct Earth { ~Earth() { // Earth's destructor printf("Making way for hyperspace bypass"); } }
Exceptions are types that communicate an error condition. exception handler
if (x == 0xFACE) {
throw std::runtime_error{ "exception" };
}try-catch
try {
groucho.forget(0xC0DE);
} catch (const std::runtime_error &e) {
printf("catching with message: %s\n", e.what());
}struct Superclass {
int x;
};
struct Subclass : Superclass {
int y;
int foo() {
return x + y;
}
};Polymorphic code is code you write once and can reuse with different types.
C++ offers two polymorphic approaches. Compile-time polymorphic code incorporates polymorphic types you can determine at compile time. The other approach is runtime polymorphism, which instead incorporates types determined at runtime.
C++ achieves compile-time polymorphism through templates.
A template is a class or function with template parameters.
template<typename X, typename Y, typename Z> struct MyTemplateClass { X foo(Y&); private: Z* member; };
template<typename X, typename Y, typename Z> X my_template_function(Y& arg1, const Z* arg2) { --snip-- }
https://wandbox.org/
https://www.godbolt.org
https://en.wikipedia.org/wiki/C%2B%2 https://code.visualstudio.com/docs/languages/cpp https://code.visualstudio.com/docs/cpp/cpp-debug