ProgramGuru

Group Related Fields

Group Related Fields

A struct groups fields describing one record.

A student’s name and mark can travel together rather than relying on two separate collections staying aligned.

Before this lesson, review Inspect and Edit Names when needed.

What you’ll learn

  • Use structures to group Related Fields.
  • Explain how the complete example produces Diya: 72.
  • Make the practice change and explain why the result changes or stays the same.

Follow a complete C++ example

A student’s name and mark can travel together rather than relying on two separate collections staying aligned.

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>
#include <string>

struct Student  {
  std::string name;
  int marks;
}
;
int main()  {
  Student s {
    "Diya", 72
  }
  ;
  std::cout << s.name << ": " << s.marks << '\n';
  return 0;
}

Expected output

Diya: 72
Run in C++ compiler →

Connect the code to its result

C++17 · source used in this explanation

#include <iostream>
#include <string>

struct Student  {
  std::string name;
  int marks;
}
;
int main()  {
  Student s {
    "Diya", 72
  }
  ;
  std::cout << s.name << ": " << s.marks << '\n';
  return 0;
}

Expected output

Diya: 72

A struct groups fields describing one record. A student’s name and mark can travel together rather than relying on two separate collections staying aligned.

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 Diya: 72. In this example, distinguish what the program calculates or changes from what it actually displays.

Important mistakes and boundaries

Struct members are public by default. A simple record is useful, but it does not enforce a mark rule unless your code explicitly checks it.

Change the school example

C++17 · edit this complete example

#include <iostream>
#include <string>

struct Student  {
  std::string name;
  int marks;
}
;
int main()  {
  Student s {
    "Diya", 72
  }
  ;
  std::cout << s.name << ": " << s.marks << '\n';
  return 0;
}

Your task: Use student Saira with mark 80. 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: Use student Saira with mark 80. The line becomes Saira: 80.

A struct groups fields describing one record. A student’s name and mark can travel together rather than relying on two separate collections staying aligned.

Struct members are public by default. A simple record is useful, but it does not enforce a mark rule unless your code explicitly checks it.

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>
#include <string>

struct Student  {
  std::string name;
  int marks;
}
;
int main()  {
  Student s {
    "Saira", 80
  }
  ;
  std::cout << s.name << ": " << s.marks << '\n';
  return 0;
}

Expected output

Saira: 80
Run in C++ compiler →

Check your understanding

C++17 · original program for this question

#include <iostream>
#include <string>

struct Student  {
  std::string name;
  int marks;
}
;
int main()  {
  Student s {
    "Diya", 72
  }
  ;
  std::cout << s.name << ": " << s.marks << '\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

Diya: 72

A struct groups fields describing one record. A student’s name and mark can travel together rather than relying on two separate collections staying aligned. Struct members are public by default. A simple record is useful, but it does not enforce a mark rule unless your code explicitly checks it.

What to remember

A struct groups fields describing one record. Struct members are public by default. A simple record is useful, but it does not enforce a mark rule unless your code explicitly checks it.

Useful connections: Inspect and Edit Names, 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: Name a Fixed Set of States →