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> Basically, an instruction or set of one that may or may not be executed, with a predetermined condition as the deciding factor.

> Syntax type:

• If
• If – Else
• Switch-case

> Syntax:

1. If

• if (boolean expression) statement;

or

• if (boolean expression){

  statement1;

  statement2;

  ……

  }

If the boolean expression is true, then a statement or set of statements will be executed.

2. If – Else

• if (boolean expression) statement1; else statement2;

or

• if (boolean expression){statement1;

  statement2;

  ……

  }

  else {

  statement3;

  statement4;

  …

  }

If boolean expression is true, then statement 1 or set of statement 1 will be executed. If false, then statement 2 or set of statement 2 will be executed.

3. Nested-If

• if (boolean expression) statement1;if (boolean expression) statement2;

  if (boolean expression) statement3;

or

• if (boolean expression) statement1;else

  if (boolean expression) statement2;

  else

  if (boolean expression) statement3;

• Only occurs when the word IF appeared more than once within IF statement.

> Switch-case

• Basically, only use this if the numbers in if-else is too much of a pain for you to calculate.
• If matches with a case constant value, then it will execute related statement/s.
• If nothing matches, it’ll execute default statement/s

Syntax:

• switch (expression) {

  case constant1 : statements1; break;

  case constant2 : statements2; break;

  default : statements;

  }

> ?:

• Similar to IF statement, but returns value.

Syntax:

• condition ? then-expression : else-expression

Example:

• if(a > b)

  max_value = a;

  else

  max_value = b;

  as

  max_value = (a > b) ? a : b;

Error Type

1. Compile-Time Error

• Caused by Syntax Error

2. Link-Time Error

• Successfully compile, but caused link error
• Caused by no object code at link time

3. Run-Time Error

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

4. Logical Error

• Wrong result caused by incorrect flow / algorithm.

For examples on Errors, please try coding with wrong codes at Visual Express C++, or you can search for screenshots of examples at Google. I’m too lazy to give one to you. It’s a pain.