![ C language consist of some characters set, numbers
and some special symbols. The character set of C
consist of all the alphabets of English language.
C consist of
• Alphabets a to z, A to Z
• Numeric 0,1 to 9
• Special Symbols {,},[,],?,+,-,*,/,%,!,;,and more
The words formed from the character set are building
blocks of C and are sometimes known as tokens.
These tokens represent the individual entity of
language. The following different types of token are
used in C
1) Identifiers 2) Keywords 3)
Constants 4](https://image.slidesharecdn.com/basicsofc-191115085057/85/M-Florence-Dayana-Basics-of-C-Language-4-320.jpg)
M.Florence Dayana / Basics of C Language
- 1. M.Florence Dayana Head, Dept. of BCA Bon Secours College for Women, Thanjavur 1
- 2. C was originally developed in the 1970s, by Dennis Ritchie at Bell Telephone Laboratories, Inc. C is a High level , general –purpose structured programming language. Instructions of C consists of terms that are very closely same to algebraic expressions, consisting of certain English keywords such as if, else, for ,do and while C contains certain additional features that allows it to be used at a lower level , acting as bridge between machine language and the high level languages. This allows C to be used for system programming as well as for applications programming 2
- 3. • What is C? • C is a structured, relatively low-level, portable programming language. • Why study C? • Many popular software tools are written in C. • Has strongly influenced many other languages. • C-shell, java, C++, Perl, etc. • Forces the user to understand fundamental aspects of programming. • Very concise language. 3
- 4. C language consist of some characters set, numbers and some special symbols. The character set of C consist of all the alphabets of English language. C consist of • Alphabets a to z, A to Z • Numeric 0,1 to 9 • Special Symbols {,},[,],?,+,-,*,/,%,!,;,and more The words formed from the character set are building blocks of C and are sometimes known as tokens. These tokens represent the individual entity of language. The following different types of token are used in C 1) Identifiers 2) Keywords 3) Constants 4
- 5. • A 'C' program consist of two types of elements , user defined and system defined. • Identifiers is nothing but a name given to these elements. • An identifier is a word used by a programmer to name a variable , function, or label. • identifiers consist of letters and digits, in any order, except that the first character. • Identifiers consist of letters and digits if any order, except that the first character must be letter. • Both Upper and lowercase letters can be used 5
- 6. • Keywords are nothing but system defined identifiers. • Keywords are reserved words of the language. • They have specific meaning in the language and cannot be used by the programmer as variable or constant names • C is case sensitive, it means these must be used as it is • 32 Keywords in C Programming auto double int struct break else long switch case enum register typedef char extern return union const float short unsigne d continue for signed void default goto sizeof volatile do if static while 6
- 7. • A variable is nothing but a name given to a storage area that our programs can manipulate. • Each variable in C has a specific type, which determines the size and layout of the variable's memory • The name of a variable can be composed of letters, digits, and the underscore character. • Upper and lowercase letters are distinct because C is case-sensitive. There are following basic variable types − Type Description • char Typically a single octet(one byte). This is an integer type. • int The most natural size of integer for the machine. • float A single-precision floating point value. • Double A double-precision floating point value. 7
- 8. • A constant is a value or an identifier whose value cannot be altered in a program. For example: 1, 2.5, • As mentioned, an identifier also can be defined as a constant. eg. const double PI = 3.14 • Here, PI is a constant. Basically what it means is that, PI and 3.14 is same for this program. Integer constants • A integer constant is a numeric constant (associated with number) without any fractional or exponential part. • There are three types of integer constants in C programming: • decimal constant (base 10) • octal constant (base 8) • hexadecimal constant (base 16) 8
- 9. Floating-point constants • A floating point constant is a numeric constant that has either a fractional form or an exponent form. For example: 2.0,0.0000234,-0.22E-5 Character constants • A character constant is a constant which uses single quotation around characters. For example: 'a', 'l', 'm', 'F' String constants • String constants are the constants which are enclosed in a pair of double-quote marks. For example: "good" ,"x", "Earth is roundn" 9
- 10. Sometimes, it is necessary to use characters which cannot be typed or has special meaning in C programming. For example: newline(enter), tab, question mark etc. In order to use these characters, escape sequence is used. • For example: n is used for newline. • The backslash ( ) causes "escape" from the normal way the characters are interpreted by the compiler. Escape Sequences Character • b Backspace f Form feed n Newline r Return • t Horizontal tab v Vertical tab • Backslash ' Single quotation mark • " Double quotation mark ? Question mark • 0 Null character 10
- 11. • An operator is a symbol which operates on a value or a variable. For example: + is an operator to perform addition. C programming has wide range of operators to perform various operations. For better understanding of operators, these operators can be classified as: • Arithmetic Operators • Increment and Decrement Operators • Assignment Operators • Relational Operators • Logical Operators • Conditional Operators • Bitwise Operators 11
- 12. Operator Meaning of Operator • + addition or unary plus • - subtraction or unary minus • * multiplication • / division • % remainder after division ( modulo division) 12
- 13. 1. C programming has two operators increment ++ and decrement -- to change the value of an operand (constant or variable) by 1. 2. Increment ++ increases the value by 1 whereas decrement -- decreases the value by 1. 3. These two operators are unary operators, meaning they only operate on a single operand. eg. int a=10, b=100 ++a = 11 13
- 14. • An assignment operator is used for assigning a value to a variable. The most common assignment operator is = Operator Example Same as • = a = b a = b • += a += b a = a+b • -= a -= b a = a-b • *= a *= b a = a*b • /= a /= b a = a/b • %= a %= b a = a%b 14
- 15. • A relational operator checks the relationship between two operands. If the relation is true, it returns 1; if the relation is false, it returns value 0. • Relational operators are used in decision making and loops. Operator Meaning of Operator Example • == Equal to 5 == 3 returns 0 • > Greater than 5 > 3 returns 1 • < Less than 5 < 3 returns 0 • != Not equal to 5 != 3 returns 1 • >= Greater than or equal to 5 >= 3 returns 1 • <= Less than or equal to 5 <= 3 return 0 15
- 16. • Logical operators, like relational operators, are typically used in conditional expressions 1. if ( (a == 1) && (b < 3) || (c == 1) ) etc. • However, these can also be used in regular expressions int a = 1, b = 2, c = 3, d; d = ( a > b ) || ( c == (b – 1) ); What is the value of d here? 16
- 17. 17 • Comparision Operators: <, > , <=, >= , !=, ==, !, &&, || . •example: • int a=4, b=5; • a<b returns a true(non zero number) value. • Bitwise Operators: <<, >>, ~, &, | ,^ . •example • int a=8; • a= a>>1; // value of a becomes 4
- 18. 18 • Meaning of a + b * c ? is it a+(b*c) or (a+b)*c • All operators have precedence over each other • *, / have more precedence over +, - . • If both *, / are used, associativity comes into picture. (more on this later) • example : • 5+4*3 = 5+12= 17.
- 19. 19 Highest on top ++ -- (Postfix) ++ -- (Prefix) * / % + - << >> < > & | && ||
- 20. 20 • Input operation • an instruction that copies data from an input device into memory • Output operation • an instruction that displays information stored in memory to the output devices (such as the monitor screen)
- 21. 21 • A C function that performs an input or output operation • A few functions that are pre-defined in the header file stdio.h such as : •printf() •scanf() •getchar() & putchar()
- 22. 22 • Used to send data to the standard output (usually the monitor) to be printed according to specific format. • General format: • printf(“string literal”); • A sequence of any number of characters surrounded by double quotation marks. • printf(“format string”, variables); • Format string is a combination of text, conversion specifier and escape sequence.
- 23. 23 • Example: • printf(“Thank you”); • printf (“Total sum is: %dn”, sum); • %d is a placeholder (conversion specifier) • marks the display position for a type integer variable • n is an escape sequence • moves the cursor to the new line
- 24. Principles of Programming - NI 2005 24 • Read data from the standard input device (usually keyboard) and store it in a variable. • General format: • scanf(“Format string”, &variable); • Notice ampersand (&) operator : • C address of operator • it passes the address of the variable instead of the variable itself • tells the scanf() where to find the variable to store the new value
- 25. Principles of Programming - NI 2005 25 • Example : int age; printf(“Enter your age: “); scanf(“%d”, &age); • Common Conversion Identifier used in printf and scanf functions. printf scanf int %d %d float %f %f double %f %lf char %c %c string %s %s
- 26. Principles of Programming - NI 2005 26 • If you want the user to enter more than one value, you serialise the inputs. • Example: float height, weight; printf(“Please enter your height and weight:”); scanf(“%f%f”, &height, &weight);
- 27. Principles of Programming - NI 2005 27 • getchar() - read a character from standard input • putchar() - write a character to standard output • Example: #include <stdio.h> void main(void) { char my_char; printf(“Please type a character: ”); my_char = getchar(); printf(“nYou have typed this character: ”); putchar(my_char); }
- 28. Principles of Programming - NI 2005 28 • Alternatively, you can write the previous code using normal scanf and %c placeholder. • Example #include <stdio.h> void main(void) { char my_char; printf(“Please type a character: ”); scanf(“%c”,&my_char); printf(“nYou have typed this character: %c ”, my_char); }
- 29. 29 • The operands of a binary operator must have a the same type and the result is also of the same type. • Integer division: c = (9 / 5)*(f - 32) The operands of the division are both int and hence the result also would be int. For correct results, one may write c = (9.0 / 5.0)*(f - 32) • In case the two operands of a binary operator are different, but compatible, then they are converted to the same type by the compiler. The mechanism (set of rules) is called Automatic Type Casting. c = (9.0 / 5)*(f - 32)
- 30. 30 1. char and short operands are converted to int 2. Lower data types are converted to the higher data types and result is of higher type. 3. The conversions between unsigned and signed types may not yield intuitive results. 4. Example float f; double d; long l; int i; short s; d + f f will be converted to double i / s s will be converted to int l / i i is converted to long; long Hierarchy Double float long Int Short and char
- 31. 31 • Identify the start of the program • Every C program has a main ( ) • 'main' is a C keyword. We must not use it for any other variable. • 4 common ways of main declaration int main(void) { return 0; } void main(void) { } main(void) { } main( ) { }
- 32. • Note: all statements end with a semicolon; • Statements can (with a few exceptions) be broken across lines or ganged on a single line • Commas separate multiple declarations • Blank lines have no effect • Extra spaces between tokens has no effect. • Comments are ignored by the compiler 32
- 33. 33 • A specification of an action to be taken by the computer as the program executes. • Each statement in C needs to be terminated with semicolon (;) • Example: #include <stdio.h> void main(void) { printf(“I love programmingn”); printf(“You will love it too once ”); printf(“you know the trickn”); } statement statement statement
- 34. • So far our C programs are as follows: /* description of program */ #include <stdio.h> /* any other includes go here */ int main(){ /* program body */ return 0; } • Let’s learn more about the structure of “program body” 34
- 35. 35