155 lines
4.8 KiB
HTML
155 lines
4.8 KiB
HTML
<!DOCTYPE html>
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<head>
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<style>
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body {
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margin:0;
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padding:0;
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}
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main {
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margin:2em;
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}
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header {
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display:block;
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width: 100%;
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background-color:black;
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padding:1em;
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}
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header * {
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color:white;
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display:inline;
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padding-left:1em;
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}
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code, pre {
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whitespace: normal;
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}
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.cblock {
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padding-left: 1em;
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padding-right: 1em;
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display: inline-block;
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margin-left: 5em;
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background-color:lightgray;
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}
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</style>
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</head>
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<body>
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<header>
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<span style="font-size: 32px;">Lucas Rufkahr</span>
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<a href="https://lukerufkahr.com">Home</a>
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<a href="https://lukerufkahr.com/notes.html">Notes</a>
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<a href="https://lukerufkahr.com/fun_stuff.html">Fun</a>
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</header>
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<main>
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<h1>C++ Notes</h1>
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<h2>ToC</h2>
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<ul>
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<li><a href="#basics">Basics</a></li>
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<ul>
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<li><a href="#basics-introduction">Introduction</a></li>
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<li><a href="#basics-variables">Variables</a>
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<li><a href="#basics-operators">Operators</a>
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</ul>
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<li><a href="#control_flow">Control Flow</a></li>
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</ul>
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<hr>
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<h2 id="basics">Basics</h2>
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<h3 id="basics-introduction">I. Introduction</h3>
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<p>
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A C++ program generally consists of preprocessor directives and the main function.<br>
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<br>
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A preprocessor directive tells the C++ preprocessor what to do before compiling. You can use this to include files, create macros, and determine compiling based on conditions. For example, include a file using <code>#include <iostream></code> This will include the iostream file from the C++ standard library.<br>
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<br>
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The main function looks like:
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<code class="cblock"><pre>int main() {
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<!-----> std::cout << "Hello world" << '\n';
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<!-----> return 0;
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<!----->}</pre></code>
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The <code>int main() {</code> is the declaration of the main function denoting it returns type int. <code>return 0;</code> is the return statement for the function. It is returning the integer 0. This tells the operating system, OK Quit the program safely.
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</p>
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<h3 id="basics-variables">II. Variables</h3>
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<p>
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A variable lets you allocate some memory in the computer and use it to store values. You can also recall the values for later. Variables contain a memory address and an identifier. An identifier can be *almost* anything you wish it to be.<br>
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<br>
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Variables naming rules:
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<ul>
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<li>Cannot start with a number.</li>
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<li>Can only contain alphanumeric characters and underscores.</li>
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<li>Cannot contain any reserved keywords <a href="https://en.cppreference.com/w/cpp/keyword.html">(see here)</a>.
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<li>If starting with an underscore, it can only start with one.</li>
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</ul>
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All variables have denoted types and they refer to what kind of variable it is. All variables also have a bit size and this denotes the range of values that can be stored.<br>
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<br>
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Variable types:
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<ul>
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<li>Integers:</li>
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<ul>
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<li>short int:</li>
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<ul>
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<li>Size: 2 bytes.</li>
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<li>Range: -32,768 to 32,767</li>
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</ul>
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<li>int:</li>
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<ul>
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<li>Size: 4 bytes.</li>
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<li>Range: -2 billion to 2 billion</li>
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</ul>
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<li>short:</li>
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<ul>
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<li>Size: 8 bytes.</li>
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</ul>
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</ul>
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<li>Floats:</li>
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<ul>
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<li>float:</li>
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<ul>
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<li>Size: 4 bytes.</li>
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<li>6 significant figures.</li>
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</ul>
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<li>double:</li>
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<ul>
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<li>Size: 8 bytes.</li>
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<li>15 significant figures.</li>
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</ul>
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<li>long double:</li>
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<ul>
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<li>Size: 16 bytes.</li>
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<li>19 significant figures.</li>
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</ul>
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</ul>
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<li>Character:</li>
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<ul>
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<li>Type: char</li>
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Stores an integer value representative of an "ASCII" character.
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<li>Size: 1 byte.</li>
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</ul>
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<li>String:</li>
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<ul>
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Stores an indexable array of characters.
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<li>Usage: <code>#include <string></code>
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<li>Variable creation: <code>std::string identifier = "string literal";</code></li>
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</ul>
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<li>Boolean:</li>
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<ul>
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Stores an integer value of 0 or 1 representative of false or true respectively.
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<li>Type: bool</li>
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<li>Size: 1 byte</li>
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</ul>
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</ul>
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<br>
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Variables are always declared before they are initialized. This means you must determine the type and the identifier before you store any values into it.<br>
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<br>
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<code class="cblock"><pre>int main() {
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<!-----> int a; // Declaration
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<!-----> a = 1; // Initialization
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<!-----> int b = 2; // Declaration then initialization
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<!----->}</pre></code><br>
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<br>
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Constant types are variables identified by <code>const</code> in their type definition. These are not allowed to be modified after they are declared and must be initialized at declaration.
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</p>
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<h3 id="#basics-operators">Operators</h3>
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<h2 id="control_flow">Control Flow</h2>
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</main>
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</body>
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