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Lab03

Lab03. Dayu Zhang 9/10/2014. Outline. Brief Review of the 4 Steps in Hello.cpp Example Understand endl and n Understand Comment Programming Exercise - Calculate Area of a Square. Steps of Hello.cpp. Create Command: touch Hello.cpp Edit Command: vi Hello.cpp Compile

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Lab03

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  1. Lab03 Dayu Zhang 9/10/2014

  2. Outline • Brief Review of the 4 Steps in Hello.cpp Example • Understand endl and \n • Understand Comment • Programming Exercise - Calculate Area of a Square

  3. Steps of Hello.cpp • Create • Command: touch Hello.cpp • Edit • Command: vi Hello.cpp • Compile • Command: g++ Hello.cpp • If there is compile error, file a.out will not be generated • Run • Command: ./a.out

  4. Distinguish In or Not In vi Editor • All commands in previous slide should be used outside of vi Editor • When in vi Editor • Insert Mode: edit code • Command Mode: save code and quit vi editor

  5. Understand endl and \n • In C++, they both mean new line. • endl --- it is used outside of “ ” • \n --- it is used inside of “ ” • \ --- it has special meaning • If you want to print \, you cannot use cout << “\”; Instead, you will use cout << “\\”;

  6. First, know the Difference int main() { cout << "hi"; return 0; } int main() { cout << "hi" << endl; return 0; }

  7. Q1:What is the output? int main() { cout << "hi" << endl << endl << "hello" << endl; return 0; } A. B. hi hello hi hello

  8. Q2: Are the outputs the same? int main() { cout << "hi" << endl; return 0; } int main() { cout << "hi\n"; return 0; } A. Yes B. No

  9. Q3: What is the output? int main() { cout << "today\ntomorrow" << endl; return 0; } A. B. today\ntomorrow today tomorrow

  10. Q4: What is the output? int main() { cout << "\\" << endl; return 0; } A. \ B. \\

  11. Q5: What is the output? int main() { cout << "\n" << endl; return 0; } A. B. \n (Choice A means zero or more new lines)

  12. Q6: What is the output? int main() { cout << "endl" << endl; return 0; } A. B. endl

  13. Q7: What is the output? int main() { cout << "\\n" << endl; return 0; } A. \\n B. \n

  14. Q8: What is the output? int main() { cout << "\\\\" << endl; return 0; } A. \\ B. \\\\

  15. Q9: What is the output? int main() { cout << \n << endl; return 0; } A. \n B. Program could not be compiled, thus no output

  16. Understand Comment • // Current line is comment. • You should always put your name in the first line of programming assignment // Name: LastName, FristName • /* */ All lines in between are comments.

  17. Exercise: Calculate Area of a Square • Write a program that asks user to input the length of the side of a square (type: int) and then output the area of the square.

  18. Answers to Output Questions • Q1 B • Q2 A • Q3 B • Q4 A • Q5 A • Q6 B • Q7 B • Q8 A • Q9 B

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