![Symbol Name
% Percent sign
# Number sign
& ampersand
^ caret
* asterisk
- minus
+ Plus
< Less than or opening
angle bracket
> Greater than or closing
angle bracket
( Left parenthesis
) Right parenthesis
[ Left bracket
] Right bracket
{ Left brace
} Right brace
!= Not equal to
Symbol Name
, comma
. period
; Semi colon
: colon
? Question
mark
apostrophe
quotation
mark
! exclamation
mark
| vertical bar
/ slash
back slash
~ tilde
_ underscore
$ Dollar sign](https://image.slidesharecdn.com/1173237747module2part1basicsofcprogramming1-241209023910-2883d110/85/1173_237_747_Module_2_Part1__Basics_of_C_programming__1_-pptx-6-320.jpg)
1173_237_747_Module_2_Part1__Basics_of_C_programming__1_.pptx
- 1. Basics of C Programming
- 2. The name C: C was an offspring of BCPL (Basic Combined Programming Language) called B. Dennis Ritchie modified it and the new language was named C. Importance of C Rich set of built in functions and operators can be used to write any complex program. The C compiler combines the capabilities of an assembly language with the features of a high level language well suited for writing system software and business packages. Programs written in C are efficient and fast due to variety of data types and powerful operators. Less number of keywords- 32 only Highly portable can be transferred from machine to machine with very little or no modifications. It is important when we plan to use a new computer with a different operating system. Well suited for structured programming Program can be divided into modules. Modular structure makes debugging, testing and maintenance easy.
- 3. Ability to extend itself A C program is a collection of functions supported by C Library. We can add our own functions to the C library. With the addition of large number of functions the programming task becomes simpler
- 4. Process of compiling and running a C program
- 5. The C Character set A character set denotes any alphabet, digit or special symbol which are the basic building blocks used to form program elements (variables, constants, operators) The characters in C fall into the following groups 1. Letters: Upper case AZ, Lower case az 2. Digits: All decimal digits 0.9 3. Special characters
- 6. Symbol Name % Percent sign # Number sign & ampersand ^ caret * asterisk - minus + Plus < Less than or opening angle bracket > Greater than or closing angle bracket ( Left parenthesis ) Right parenthesis [ Left bracket ] Right bracket { Left brace } Right brace != Not equal to Symbol Name , comma . period ; Semi colon : colon ? Question mark apostrophe quotation mark ! exclamation mark | vertical bar / slash back slash ~ tilde _ underscore $ Dollar sign
- 7. 4. White spaces Blank space Horizontal tab Carriage return New line Form feed The compiler ignores white spaces unless they are part of a string constant. White spaces may be used to separate words, but are prohibited between the characters of key words and identifiers ANSI C trigraph sequences Non-English keyboards may not have all the special characters. To enter certain characters C provides 3 character trigraphs- 2 question marks followed by another character For example # has the trigraph sequence ??+
- 8. C tokens The smallest individual units in a C program are known as C tokens C has 6 types of tokens C programs are written using these tokens and the syntax of the language C token are Keywords Identifiers Constants Strings Special symbols Operators
- 9. Keywords Every C word is classified as a keyword or an identifier. Keywords: Keywords are reserved words that have fixed pre-defined meanings in C. These meanings cannot be changed. Keywords serve as basic building blocks for program statements. All keywords must be written in lower case
- 11. Identifiers Identifiers are user defined names given to various program elements such as variables, functions, arrays etc. The identifiers consists of a sequence of letters and digits with a letter as the first character Both uppercase and lower case letters are permitted Lower case letters are commonly used The underscore character is also permitted in identifiers C distinguishes between lowercase and uppercase characters Valid identifiers : xy, x2y, tax_rate, _temp Invalid: 4th, X, order-no, error flag
- 12. These are the fundamental requirement of any language. Each language has its own rules for naming these identifiers Only alphabetic characters, digits and underscores are permitted. The name cannot start with a digit. Uppercase and lowercase letters are distinct. A declared keyword cannot be used as a variable name.
- 13. Constants in C++ Constants refer to fixed values that do not change during the execution of a program. They include integers, characters, floating point numbers and strings. Two types Numeric constants and character constants Numeric constants Integer and Real constants Character constants Single character constants, string constants
- 14. Rules for Numeric Type Constants 1. Commas and blank spaces cannot be included within the constant 2. The constant can be preceded by a + or - sign 3. The value of constant cannot exceed certain specified minimum and maximum bounds Integer constants An integer constant refers to a sequence of digits. They are whole numbers Integer constants can be written in three different number systems Decimal constants base 10 Octal constants base 8 Hexadecimal constants base 16
- 15. Decimal integers consist of a set of digits 09 preceded by an optional + or sign If the constant contains 2 or more digits, then the first digit should not be zero Valid decimal constants : 123, -321, 0, 6541, +78 Invalid 15 750 (blank space) 20,000 (comma) 36.0 (period) 0900 (first digit should not be zero)
- 16. Octal integer (base8) An octal integer constant can consist of any combination digits taken from the set 0 through 7 with first digit 0. It can have + or sign Valid: 012, -0467, +04013, 0, 01 Invalid: 743 (not starting with 0) 0482 (illegal digit 8) 04.17 (decimal point-illegal character) Hexadecimal integer(base16) A hexadecimal integer constant is a sequence of digits preceded by 0X It can be followed by digits 0 through 9 and letters A through F Valid : 0X2, 0X9F, oXbcd, 0X
- 17. Real constants (Floating point constants) Integer numbers are inadequate to represent quantities that vary continuously such as distances, heights, temperatures, prices and so on. These quantities are represented by numbers containing a fractional part or real numbers. Such numbers are real or floating point constants. They can be decimal notation or exponential notation. Eg.:0, 0.0083, -0.75, 12.3, 0.95 etc General form for exponential notation is Mantissa e Exponent 215.65 may be written as 2.1565e2 The mantissa may be either a real number or integer The exponent is an integer with optional + or sign E separating mantissa and exponent can be written in either lower or upper case
- 18. Valid 0.65e4, 12e-2, 1.5e+5, 3.18E3, -1.2E-1 Invalid 7.1e 4, 1.51E+2.5, $255.0, 1 Valid: 152E08, 152.0E8, 152E+8, 152E+08, 15.2e9, 1520e7 Character constants Single character constants A single character constant or simply character constant is a single character enclosed within a pair of single quote marks. Eg. 5, X, Character constants have integer values known as ASCII values. The character constant 3 and integer value 3 are not the same. ASCII- American Standard Code for Information Interchange Since each character constant represents an integer value, it is also possible to perform arithmetic operations on character constants.
- 19. String constants A string constant consists of any number of consecutive characters (letters, numbers, special characters, and blank spaces) enclosed in double quotes. Eg. Hello, GEC Thrissur, Knowledge is power, ?......!, 5+3, , X It is to be noted that X and X are different. X have an integer value where as X do not have an integer value String constants are used to make meaningful programs.
- 20. Backslash character constants The backslash character constants are used in output functions. These character combinations are also known as escape sequences a audible alert b - backspace f- form feed n- new line r- carriage return t- horizontal tab v- vertical tab single quote double quote ? question mark - backslash 0 - null
- 21. Variables A variable is a data name used to store a data value. A variable takes different values at different times during the program. It is an identifier that is used to represent some specified type of information within a designated portion of the program. In its simplest form a variable represents a single data item that is a numerical quantity or a character constant. The data item is assigned to the variable in some point in the program. The data item can be the accessed later in the program by simply referring to the variable name. The information associated with the variable may change but the datatype associated with the variable cannot change. A variable name shall be chosen in a meaningful way. A variable name can consist of letters, digits and underscore.
- 22. 1. They must begin with a letter. Some systems permit underscore as a first character. 2. ANSI standard recognizes a variable name length of 31 characters, but the first 8 characters only are treated as significant. So it is better to use meaningful names with 8 characters 3. Uppercase and lowercase are significant. 4. Variable name should not be a keyword. 5. Whitespace is not allowed. Examples of valid variable names: mark, value, sum1, ph_value Examples of invalid variable names: char, 123, price$