C++ cout

cout

• <iostream> 라이브러리

출력 형식 설정

• 여러가지 방법으로 출력 형식을 설정할 수 있다.

• +부호 붙이기, 16진수 출력, 대문자 출력

  #include <iostream>
  
  int         main()
  {
      using namespace std;
  
      cout.setf(std::ios::showpos);
      cout << 108 << endl;
  
      cout.unsetf(std::ios::showpos);
      cout << 108 << endl;
  
      cout.unsetf(std::ios::dec);
      cout.setf(std::ios::hex);
      cout << 108 << endl;
  
      cout.setf(std::ios::hex, std::ios::basefield);
      cout << 108 << endl;
  
      cout << std::dec;
      cout << 108 << endl;
  
      cout.setf(std::ios::uppercase);
      cout << std::hex;
      cout << 108 << endl;
  
      cout << std::nouppercase;
      cout << 108 << endl;
  
      cout << boolalpha << true << ' ' << false << endl;
      cout << noboolalpha << true << ' ' << false << endl;
  }
  
  

/* stdout stderr
+108
108
6c
6c
108
6C
6c
true false
1 0
*/

## `<iomanip>`

- `<iomanip>` 라이브러리를 포함하면 더 유연하게 출력 형식을 조절할 수 있다.

- 소수점 자릿수 조절, 과학적 표기법, 소수점 표시

  ```c++
  #include <iostream>
  #include <iomanip>

  void        printFloat()
  {
      using namespace std;

      cout << std::setprecision(3) << 123.456 << endl;
      cout << std::setprecision(4) << 123.456 << endl;
      cout << std::setprecision(5) << 123.456 << endl;
      cout << std::setprecision(6) << 123.456 << endl;
      cout << std::setprecision(7) << 123.456 << endl;
      cout << endl;
  }

  int         main()
  {
      using namespace std;

      printFloat();

      cout << std::fixed;
      printFloat();

      cout << std::scientific << std::uppercase;
      cout << "this is lowercase\n";
      printFloat();

      cout << std::defaultfloat;
      cout << std::showpoint;
      printFloat();
  }


  /* stdout stderr
  123
  123.5
  123.46
  123.456
  123.456

  123.456
  123.4560
  123.45600
  123.456000
  123.4560000

  this is lowercase
  1.235E+02
  1.2346E+02
  1.23456E+02
  1.234560E+02
  1.2345600E+02

  123.
  123.5
  123.46
  123.456
  123.4560
  */

• 좌우 정렬, 공백 대신 문자 채우기

  #include <iostream>
  #include <iomanip>
  
  int         main()
  {
      using namespace std;
  
      cout << -12345 << endl;
      cout << std::setw(10) << -12345 << endl;
      cout << std::setw(10) << std::left << -12345 << endl;
      cout << std::setw(10) << std::right << -12345 << endl;
      cout << std::setw(10) << std::internal << -12345 << endl;
      cout << endl;
      cout.fill('*');
      cout << std::setw(10) << -12345 << endl;
      cout << std::setw(10) << std::left << -12345 << endl;
      cout << std::setw(10) << std::right << -12345 << endl;
      cout << std::setw(10) << std::internal << -12345 << endl;
  }
  
  

/* stdout stderr
-12345
-12345
-12345
-12345

• 12345

• ****12345

• 12345****

• ***-12345

• ****12345

• /
  ```