<!DOCTYPE html> <html> <head> <meta name="viewport" content="width=device-width, initial-scale=1"> <link rel="stylesheet" href="https://cdnjs.cloudflare.com/ajax/libs/font-awesome/4.7.0/css/font-awesome.min.css"> <style> body { margin: 0; font-family: Arial, Helvetica, sans-serif; } .topnav { overflow: hidden; background-color: #f2f2f2; } .topnav a { float: left; color: #000080; text-align: center; padding: 14px 16px; text-decoration: none; font-size:20px; } .topnav a:hover { background-color: #ddd ; color: black; } .topnav a.active { background-color:#000080 ; color:white; } div.container { width: 100%; border: 1px solid gray; } header, footer { padding: 1em; color: white; background-color: #000080; clear: left; font-size:large; text-align: center; } nav { float: left; max-width: 180px; margin: 0; padding: 1em; } nav ul { list-style-type: none; padding: 0; font-size:20px; } nav ul a { text-decoration: none; } article { margin-left: 170px; border-left: 1px solid gray; padding: 1em; overflow: hidden; } .icon-bar a { float: left; width: 5%; text-align: center; padding: 13px 0; color: #000080; font-size: 25px; } .vertical-menu { width: 180px; } .vertical-menu a { background-color:#eee; color:black; display: block; padding:15px; text-decoration: none; } .vertical-menu a:hover { background-color: #ccc; } .vertical-menu a.active { background-color: #000080; color: white; } a{ text-decoration: none; display: inline-block; padding: 9px 17px; } a:hover { background-color: #ddd; color: black; } .previous { background-color:#000080; color: white; } .next { background-color: #000080; color: white; margin-left:780px; } </style> </head> <body> <header> <h1>C Programming</h1> </header> <div class="topnav"> <div class="icon-bar"> <a class="" href="index.html"><i class="fa fa-home"></i></a> </div> <a href="allprolang.html">All Languages</a> <a class="active" href="c_overview.html">C</a> <a href="cpp_overview.html">CPP</a> <a href="java_overview.html">JAVA</a> <a href="html_overview.html">HTML</a> <a href="css_overview.html">CSS</a> <a href="javascript_overview.html">JAVASCRIPT</a> <a href="python_overview.html">PYTHON</a> <div class="icon-bar"> <a class="" href="#"><i class="fa fa-search"></i></a> </div></div> <nav> <div class="vertical-menu"> <a href="c_overview.html">Overview</a> <a href="c_prostuct.html">Program Structures</a> <a href="c_basicsyntax.html">Basic Syntax</a> <a href="c_datatypes.html">DataTypes</a> <a href="c_variables.html">Variables</a> <a class="active" href="c_constliterals.html">Constants&Literals </a> <a href="c_operators.html">Operators</a> <a href="c_desisonmake.html">Decision Making</a> <a href="c_loops.html">Loops</a> <a href="c_functions.html">Functions</a> <a href="c_scope.html">Scope Rules</a> <a href="c_arrays.html">Arrays</a> <a href="c_pointers.html">Pointers</a> <a href="c_strings.html">Strings</a> <a href="c_structunion.html">Structures&Unions </a> <a href="c_ipop.html">Input&Output </a> <a href="c_fileio.html">File I/O </a> </div> </nav> <article> <a href="c_variables.html" class="previous">« Previous</a> <a href="c_operators.html" class="next">Next »</a> <h1 style="color:#000080";> Constants & Literals In C</h1> <p>Constants refer to fixed values that the program may not alter during its execution. These fixed values are also called literals.</p> <p>Constants can be of any of the basic data types like an integer constant, a floating constant, a character constant, or a string literal. There are enumeration constants as well.</p> <p>Constants are treated just like regular variables except that their values cannot be modified after their definition.</p> <p><h2>Integer Literals</h2></p> <p>An integer literal can be a decimal, octal, or hexadecimal constant. A prefix specifies the base or radix: 0x or 0X for hexadecimal, 0 for octal, and nothing for decimal.</p> An integer literal can also have a suffix that is a combination of U and L, for unsigned and long, respectively. The suffix can be uppercase or lowercase and can be in any order.</p> <p>Here are some examples of integer literals:<br></p> <img src="images/c_literal1.png"/> <p><h2>Floating-point Literals</h2></p> <p>A floating-point literal has an integer part, a decimal point, a fractional part, and an exponent part. You can represent floating point literals either in decimal form or exponential form.</p> <p>While representing decimal form, you must include the decimal point, the exponent, or both; and while representing exponential form, you must include the integer part, the fractional part, or both. The signed exponent is introduced by e or E.</p> <p>Here are some examples of floating-point literals:</p> <img src="images/c_literal2.png"/> <p><h2>Character Constants</h2></p> <p>Character literals are enclosed in single quotes, e.g., 'x' can be stored in a simple variable of char type.</p> <p>A character literal can be a plain character (e.g., 'x'), an escape sequence (e.g., '\t'), or a universal character (e.g., '\u02C0').</p> <p>There are certain characters in C that represent special meaning when preceded by a backslash, for example, newline (\n) or tab (\t). Here, you have a list of such escape sequence codes:</p> <img src="images/c_literal3.png"> <img src="images/c_literal4.png"> <p>Following is the example to show a few escape sequence characters:</p> <img src="images/c_literal5.png"> <p>When the above code is compiled and executed, it produces the following result:</p> <p><h3>Hello World</h3></p> <p><h2>String Literals</h2></p> <p>A "string literal" is a sequence of characters from the source character set enclosed in double quotation marks (" "). String literals are used to represent a sequence of characters which, taken together, form a null-terminated string. You must always prefix wide-string literals with the letter L.</p> <img src="images/c_literal6.png"> <p><h2>Defining Constants</h2></p> <p>There are two simple ways in C to define constants:</p> <p>* Using #define preprocessor</p> <p>* Using const keyword</p> <p><h3>The #define Preprocessor</h3></p> Given below is the form to use #define preprocessor to define a constant:</p> <p>#define identifier value</p> </p>The following example explains it in detail:</p> <img src="images/c_literal7.png"> <img src="images/c_literal8.png"> <p>When the above code is compiled and executed, it produces the following result:</p> <p><h3>value of area : 50</h3></p> <p><h2>The const Keyword</h2></p> <p>You can use const prefix to declare constants with a specific type as follows:</p> <p>const type variable = value;<p> <p>The following example explains it in detail:</p> <img src="images/c_literal9.png"> <p>When the above code is compiled and executed, it produces the following result:</p> <p><h3>value of area : 5</h3></p> <p>Note that it is a good programming practice to define constants in CAPITALS.</p> <a href="c_variables.html" class="previous">« Previous</a> <a href="c_operators.html" class="next">Next »</a> </article> <footer>Devoloped by LE's</footer> </body> </html>