TESTING AND DEBUGGING

TESTING AND DEBUGGING

•      Computer programs are subject to errors as they are written by human being.

•       Programs errors are known as bugs

What is DEBUGGING?

•      The process of finding and removing errors in a computer program is known as debugging

What is TESTING?

•      Testing is the process of making sure that the program performs the intended task

•      Debugging is the process of finding and eliminating program errors.

•      Testing and debugging are important steps in developing computer program.

Types of Errors

•      There are two types of errors that occur in a computer program:

1.    Syntax errors

2.    Logical errors

1.  Syntax errors

•      Syntax errors result when the rules or syntax/grammar of the programming languages are not followed.

•      For example, the C statement c = (a+b/2 has a syntax error. In this example, the syntax error is a missing closing parenthesis.

•      All language processors (compilers, interpreter & assemblers) are designed to detect syntax errors.

•      The language processors print error messages that indicate the number of the statement having error and give hints about the nature of the error.

•    These error messages are very useful and are used by the programmers to rectify the syntax errors in the programs.

•      A single syntax error can causes multiple error messages.

2.  Logical Errors

•      Logical error occurs when the logic of the program is incorrect and they are difficult to find and remove since they are not detected by the compiler. 

•      Logical error is an error in planning the program’s logic

•      In this case the language processor successfully translates the code into machine code.

•       The computer actually doesn’t know that the error has been made.

•      It follows the program instructions and outputs the incorrect results or stops during execution.

•      The computer doesn’t tell what is wrong.

•      For example, if a C instruction should be “a=b*c” but has been coded as “a=b+c”, this error will not be detected by the language processor since no language rules have been violated. However, the output produced will be wrong.

•      In order to determine whether or not a logical error exists, the program must be tested. The purpose of testing is to determine whether the results are correct or not.