The compiler must perform static checking (checking done at compiler time).This ensures that certain types of programming errors will be detected and reported.

 A compiler must check that the source program follows both the syntactic and semantic conversions of the source language. This checking is called static checking example of static checks include.

Some example of static checks is:-

 Type checks:- A compiler should report an error if an operator is applied to an incompatible operand.

Flow-of-control checks:- Statements that cause flow of control to leave a construct must have some place to which to transfer flow of control. For example, branching to non-existent labels.

Uniqueness checks: - Objects should be defined only once. This is true in many languages.

Name-related checks: - Sometimes, the same name must appear two or more times. For example, in Ada the name of a block must appear both at the beginning of the block and at the end.

A compiler should report an error if an operator is applied to an incompatible operand. This checking is called Type checking.

Type information gathered by a type checker may be needed when code is generated. For example, arithmetic operators may be different at the machine level for different types of operands (real and integer).


The type analysis and type checking is an important activity done in the semantic analysis phase. The need for type checking is-

  • To detect the errors arising in the expression due to incompatible operand.
  • To generate intermediate code for expressions and statements. Typically language supports two types of data types- basic and constructed.
The basic data type are- integer, character, and real, Boolean, enumerated data type. And Arrays, record (structure),set and pointer are the constructed types. The constructed data types are build using basic data types.

Fig 1:- Position of Type checking
Type Expression:- Type of a language construct. It is either a basic      type or is formed by applying an operator called a type constructor to other type expressions.
A type system is a collection of rules for assigning type expression to the various parts of a program. A type checker implements a type system. Different type system may be used by different compilers or processors of the system Language.
Checking done by a compiler is said to be static checking of types, while checking done when the target program runs is terminal dynamic checking of types.
 A source type system eliminates the need for dynamic checking for type errors because it allows us to determine statically that these errors cannot occur when the target program runs.
Type checking should have a property of error recovery.
Python Programming ↓ 👆
Java Programming ↓ 👆
JAVA EasyExamNotes.com covered following topics in these notes.
JAVA Programs
Principles of Programming Languages ↓ 👆
Principles of Programming Languages
EasyExamNotes.com covered following topics in these notes.

Previous years solved papers:
A list of Video lectures References:
  1. Sebesta,”Concept of programming Language”, Pearson Edu 
  2. Louden, “Programming Languages: Principles & Practices” , Cengage Learning 
  3. Tucker, “Programming Languages: Principles and paradigms “, Tata McGraw –Hill. 
  4. E Horowitz, "Programming Languages", 2nd Edition, Addison Wesley

    Computer Organization and Architecture ↓ 👆

    Computer Organization and Architecture 

    EasyExamNotes.com covered following topics in these notes.

    1. Structure of desktop computers
    2. Logic gates
    3. Register organization
    4. Bus structure
    5. Addressing modes
    6. Register transfer language
    7. Direct mapping numericals
    8. Register in Assembly Language Programming
    9. Arrays in Assembly Language Programming


    1. William stalling ,“Computer Architecture and Organization” PHI
    2. Morris Mano , “Computer System Organization ”PHI

    Computer Network ↓ 👆
    Computer Network

    EasyExamNotes.com covered following topics in these notes.
    1. Data Link Layer
    2. Framing
    3. Byte count framing method
    4. Flag bytes with byte stuffing framing method
    5. Flag bits with bit stuffing framing method
    6. Physical layer coding violations framing method
    7. Error control in data link layer
    8. Stop and Wait scheme
    9. Sliding Window Protocol
    10. One bit sliding window protocol
    11. A protocol Using Go-Back-N
    12. Selective repeat protocol
    13. Application layer
    1. Andrew S. Tanenbaum, David J. Wetherall, “Computer Networks” Pearson Education.
    2. Douglas E Comer, “Internetworking with TCP/IP Principles, Protocols, And Architecture",Pearson Education
    3. KavehPahlavan, Prashant Krishnamurthy, “Networking Fundamentals”, Wiley Publication.
    4. Ying-Dar Lin, Ren-Hung Hwang, Fred Baker, “Computer Networks: An Open Source Approach”, McGraw Hill.