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Inspect and Edit Names

Inspect and Edit Names

A string offers size, find and substr operations for text handling.

A report can extract the first name from a fixed space-separated school record.

Before this lesson, review Visit Each Element when needed.

What you’ll learn

  • Use string operations to inspect and Edit Names.
  • Explain how the complete example produces Diya.
  • Make the practice change and explain why the result changes or stays the same.

Follow a complete C++ example

A report can extract the first name from a fixed space-separated school record.

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>

int main()  {
  std::string name = "Diya Iyer";
  auto split = name.find(' ');
  std::cout << name.substr(0, split) << '\n';
  return 0;
}

Expected output

Diya
Run in C++ compiler →

Connect the code to its result

C++17 · source used in this explanation

#include <iostream>
#include <string>

int main()  {
  std::string name = "Diya Iyer";
  auto split = name.find(' ');
  std::cout << name.substr(0, split) << '\n';
  return 0;
}

Expected output

Diya

A string offers size, find and substr operations for text handling. A report can extract the first name from a fixed space-separated school record.

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

Important mistakes and boundaries

Find returns npos when there is no match. Byte-based positions are not a complete Unicode text-processing model.

Change the school example

C++17 · edit this complete example

#include <iostream>
#include <string>

int main()  {
  std::string name = "Diya Iyer";
  auto split = name.find(' ');
  std::cout << name.substr(0, split) << '\n';
  return 0;
}

Your task: Use Saira Shah as the record. 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 Saira Shah as the record. The extracted first name is Saira.

A string offers size, find and substr operations for text handling. A report can extract the first name from a fixed space-separated school record.

Find returns npos when there is no match. Byte-based positions are not a complete Unicode text-processing model.

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>

int main()  {
  std::string name = "Saira Shah";
  auto split = name.find(' ');
  std::cout << name.substr(0, split) << '\n';
  return 0;
}

Expected output

Saira
Run in C++ compiler →

Check your understanding

C++17 · original program for this question

#include <iostream>
#include <string>

int main()  {
  std::string name = "Diya Iyer";
  auto split = name.find(' ');
  std::cout << name.substr(0, split) << '\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

A string offers size, find and substr operations for text handling. A report can extract the first name from a fixed space-separated school record. Find returns npos when there is no match. Byte-based positions are not a complete Unicode text-processing model.

What to remember

A string offers size, find and substr operations for text handling. Find returns npos when there is no match. Byte-based positions are not a complete Unicode text-processing model.

Useful connections: Visit Each Element, 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: Group Related Fields →