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Order Grade Rules

Order Grade Rules

An else-if chain stops at its first matching condition.

Test higher grade thresholds first, then handle lower grades; use a nested decision only when one decision depends on another.

Before this lesson, review Choose Between Outcomes when needed.

What you’ll learn

  • Use else if and nested decisions to order Grade Rules.
  • Explain how the complete example produces A.
  • Make the practice change and explain why the result changes or stays the same.

Follow a complete C++ example

Test higher grade thresholds first, then handle lower grades; use a nested decision only when one decision depends on another.

Read the declarations above main before tracing its statements. Each declared name supplies the value, type or operation used later. The std:: prefix selects a name from the standard library, and cout << sends a value to the output stream.

C++17 · main.cpp · complete program

#include <iostream>

int main()  {
  int marks = 85;
  if (marks >= 80)  {
    std::cout << "A" << '\n';
  }
  else if (marks >= 50)  {
    std::cout << "Pass" << '\n';
  }
  else  {
    std::cout << "Practise" << '\n';
  }
  return 0;
}

Expected output

A
Run in C++ compiler →

Connect the code to its result

C++17 · source used in this explanation

#include <iostream>

int main()  {
  int marks = 85;
  if (marks >= 80)  {
    std::cout << "A" << '\n';
  }
  else if (marks >= 50)  {
    std::cout << "Pass" << '\n';
  }
  else  {
    std::cout << "Practise" << '\n';
  }
  return 0;
}

Expected output

A

An else-if chain stops at its first matching condition. Test higher grade thresholds first, then handle lower grades; use a nested decision only when one decision depends on another.

Trace the result: Read the complete program below from its starting values to the output operations. Each std::cout statement displays the value supplied at that point; \n begins the next line. The resulting lines, in order, are A. In this example, distinguish what the program calculates or changes from what it actually displays.

Important mistakes and boundaries

A marks >= 50 branch placed first would also catch 85. Independent if statements can both execute and are not equivalent to one chain.

Change the school example

C++17 · edit this complete example

#include <iostream>

int main()  {
  int marks = 85;
  if (marks >= 80)  {
    std::cout << "A" << '\n';
  }
  else if (marks >= 50)  {
    std::cout << "Pass" << '\n';
  }
  else  {
    std::cout << "Practise" << '\n';
  }
  return 0;
}

Your task: Set marks to 60. Before running your edited program, predict the new output and explain which stored value, condition or object changes. Keep the rest of the example intact.

Use the complete source repeated here; this task does not depend on remembering code from another section.

Worked answer and reasoning

Worked variation: Set marks to 60. The second branch prints Pass.

An else-if chain stops at its first matching condition. Test higher grade thresholds first, then handle lower grades; use a nested decision only when one decision depends on another.

A marks >= 50 branch placed first would also catch 85. Independent if statements can both execute and are not equivalent to one chain.

For a baseline run, save this source as main.cpp and use clang++ -std=c++17 -Wall -Wextra -pedantic main.cpp -o school, or equivalent g++ flags. Recompile after editing so that you run the updated executable.

The source and output below belong to the edited program. Compare them with the original example to see the consequence of this single change.

C++17 · worked variation · complete program

#include <iostream>

int main()  {
  int marks = 60;
  if (marks >= 80)  {
    std::cout << "A" << '\n';
  }
  else if (marks >= 50)  {
    std::cout << "Pass" << '\n';
  }
  else  {
    std::cout << "Practise" << '\n';
  }
  return 0;
}

Expected output

Pass
Run in C++ compiler →

Check your understanding

C++17 · original program for this question

#include <iostream>

int main()  {
  int marks = 85;
  if (marks >= 80)  {
    std::cout << "A" << '\n';
  }
  else if (marks >= 50)  {
    std::cout << "Pass" << '\n';
  }
  else  {
    std::cout << "Practise" << '\n';
  }
  return 0;
}
Before making the practice edit, what does the original C++17 program print?
Choose one answer. You can try again.

Answer and explanation

A

An else-if chain stops at its first matching condition. Test higher grade thresholds first, then handle lower grades; use a nested decision only when one decision depends on another. A marks >= 50 branch placed first would also catch 85. Independent if statements can both execute and are not equivalent to one chain.

What to remember

An else-if chain stops at its first matching condition. A marks >= 50 branch placed first would also catch 85. Independent if statements can both execute and are not equivalent to one chain.

Useful connections: Choose Between Outcomes, Give a Task a Name.

Language and design guidance: C++ Core Guidelines and C++ working draft. The draft describes an evolving language; these examples deliberately target C++17.

Reaching the recap and completing the quizzes are separate milestones.

    Next lesson: Select a Labeled Case →