Linguagem C - Aula 4.2 - Domine os comandos IF e ELSE em C (2022)

Understanding Decision Structures in Programming

Introduction to Decision Structures

• The discussion begins with an overview of decision structures, emphasizing the ability to create chains of decision-making processes.

• A review of logical operators is provided, focusing on how they can create more complex conditions within if statements.

Logical Operators Explained

• Disjunction: At least one operand must be true for the expression to be true.

• Conjunction: Both operands must be true for the expression to be true; if any operand is false, the entire expression is false.

• Negation: Inverts the logical value of a statement.

Understanding if and else

• The mechanics of if and else are explained. If the condition in if is true, its block executes; otherwise, the block under else executes.

• It’s highlighted that there cannot be an else without a preceding if, as it relies on the opposite condition established by if.

Important Rules for Using else

• An important note is that an else must always follow an associated if.

• Only one corresponding else can exist for each if, reinforcing binary logic (true/false).

Practical Example: Grading System

• A practical example illustrates a program that checks if a student has passed based on their score.

• If the score is greater than or equal to 7, "approved" is printed; otherwise, "reproved" appears.

Code Logic Breakdown

• The program prompts for input and reads a score. It then evaluates whether this score meets passing criteria using an if statement.

• If the condition (score >= 7) holds true, it prints "approved"; if false, it prints "reproved".

Alternative Approaches

• The speaker discusses alternative ways to structure similar logic while achieving identical outcomes semantically but differing syntactically.

• For instance, checking if a score is less than 7 first could yield similar results.

Conclusion and Next Steps