In this 3rd meeting in Algorithm & Programming I learn about selection.

What is selection?

• In an algorithm implementation, an instruction or block of instructions may be executed (or not) with certain predetermined condition
• Syntax:

–IF

Syntax :

if (boolean expression) statement;

or

if (boolean expression) {

     statement1;

     statement2;            Block of statements

  ……

}

If boolean expression resulting in True, then a statement or some statements will be executed.

–IF-ELSE

Syntax :

if (boolean expression) statement1;

else statement2;

or

if (boolean expression){

   statement1;

   statement2;  Block statement1

   ……

}

else {

   statement3;

   statement4;  Block statement2

   …

}

If boolean expression resulting in TRUE, then statement1 or block statement1 will be executed, if FALSE then statement2 or block statement2 be executed.

–SWITCH-CASE

• Switch-Case Operation

This statement is used in exchange of IF-ELSE, when if-else nested number of level is enormous and difficult to read

• Syntax:

switch (expression) {

  case constant1 : statements1; break;

  .

  .

  case constant2 : statements2; break;

  default : statements;

}

Error Type

• Compile-Time Error

–caused by syntax error

• Link-Time Error

–success fully compiled, but cause link error

–caused by no object code at link time

• Run-Time Error

–successfully compiled, but error at runtime. Usually caused by numerical operation such as: overflow, floating point underflow, division by zero, etc.

• Logical Error

–wrong result caused by incorrect logical flow/algorithm