Tokens in C For S-Teacher

2. The Evolution Of Programming Languages
To build programs, people use languages that are similar
to human language. The program is translated into
machine code, which computers understand.
Programming languages fall into three broad categories:
• Machine languages
• Assembly languages
• Higher-level languages

3. The Evolution of Programming Languages
- Machine Languages
• Machine languages (first-generation
languages) are the most basic type of
computer languages, consisting of strings of
numbers the computer's hardware can use.
• Different types of hardware use different
machine code. For example, IBM computers
use different machine language than Apple
computers.

4. The Evolution of Programming Languages -
Assembly Languages
• Assembly languages (second-generation
languages) are only somewhat easier to work
with than machine languages.
• To create programs in assembly language,
developers use cryptic English-like phrases to
represent strings of numbers.
• The code is then translated into object code,
using a translator called an assembler.

5. Assembly
code
Assembler
Object code

6. The Evolution of Programming Languages -
Higher-Level Languages
Higher-level languages are more powerful than assembly
language and allow the programmer to work in a more
English-like environment.
Higher-level programming languages are divided into
three “generations," each more powerful than the last:
• Third-generation languages
• Fourth-generation languages
• Fifth-generation languages

7. Higher-Level Languages -
Third-Generation Languages
• Third-generation languages (3GLs) are the first to use true
English-like phrasing, making them easier to use than
previous languages.
• 3GLs are portable, meaning the object code created for one type
of system can be translated for use on a different type of system.
 The following languages are 3GLs:
 FORTAN C
 COBOL C++
 BASIC Java
 Pascal ActiveX

8. Fundamentals and History of C
C is developed by Dennis Ritchie
C is a structured programming language
C supports functions that enables easy
maintainability of code, by breaking large file into
smaller modules
Comments in C provides easy readability
C is a powerful language

9. HISTORY OF ANSI C
Year Language Developed By/Speciality
1960 ALGOL First Language used block
structure
1967 BCPL (Basic Complied
Programming Language)
Martin Richards
1970 B Ken Thomson
1972 B,BCPL,ALGOL 
C
Dennis Ritchie

10. POINTS TO REMEMBER
Case Sensitive
• Case matters in C. ‘A’ is not ‘a’
• Add plenty of comments (/* */ or //)
• Good layout, not:
main() {printf("Hello Worldn");}
• Use meaningful variable names
• Initialize your variables
• Use parentheses to avoid confusion:
a=(10.0 + 2.0) * (5.0 - 6.0) / 2.0

11. 1. Letters: A . . . . Z and a . . . . z .
2. Decimal digits: 0 to 9
3. Special Characters: . , ; : ? ‘ “ ! | / ~ ` _ $ % &
^ * - + < > ( ) { } [ ] #
White spaces:
Blank space
Horizontal tab
Vertical tab
Carriage return
New line
Form feed
Character Set

12. Smallest individual units like individual words
and punctuation marks are called tokens. They are 6
types.
1. Keywords
2.Constants
3. Identifiers
4.Strings
5.Characters
6.Special symbols
C Tokens

13. • cannot be used as variable name or function name
• written in lowercase
S.No Primitive
data types
User
Defined data
types
Constants Statements Memory
types
Operator
1 char enum const break auto size of
2 double union type def case extern
3 long struct continue register
4 short default static
5 signed do volatile
6 unsigned else
7 void for
8 float goto
9 int if
10 return
11 switch
12 while
Keywords