C# 기본 문법

기본 문법은 타 언어들과 거의 비슷하다고 생각한다.

C# 출력

Console.WriteLine("Hello World!");

변수 선언 및 사용

문자열 기본 사용

string aFriend = "Bill";
Console.WriteLine(aFriend);
===========================
출력
Bill

aFriend = "Maria";
Console.WriteLine(aFriend);
===========================
출력
Maria

Console.WriteLine("Hello " + aFriend);
===========================
출력
Hello Bill

Console.WriteLine($"Hello {aFriend}");
=====================================
출력
Hello Bill

문자열 변수 작업

string firstFriend = "Maria";
string secondFriend = "Sage";
Console.WriteLine($"My friends are {firstFriend} and {secondFriend}");
=====================================================================
출력
My friends are Maria and Sage

Console.WriteLine($"The name {firstFriend} has {firstFriend.Length} letters.");
Console.WriteLine($"The name {secondFriend} has {secondFriend.Length} letters.");
출력
The name Maria has 5 letters.
The name Sage has 4 letters.

더 많은 문자열 작업

string greeting = "      Hello World!       ";
Console.WriteLine($"[{greeting}]");
=======================================================
출력
[      Hello World!       ]

=======================================================
string trimmedGreeting = greeting.TrimStart();
Console.WriteLine($"[{trimmedGreeting}]");
=======================================================
출력
[Hello World!       ]

=======================================================
trimmedGreeting = greeting.TrimEnd();
Console.WriteLine($"[{trimmedGreeting}]");
=======================================================
출력
[      Hello World!]

=======================================================
trimmedGreeting = greeting.Trim();
Console.WriteLine($"[{trimmedGreeting}]");

=======================================================
출력
[Hello World!]

=======================================================

대,소문자

string sayHello = "Hello World!";
Console.WriteLine(sayHello);
sayHello = sayHello.Replace("Hello", "Greetings");
Console.WriteLine(sayHello);
=====================================================
출력
Hello World!
Greetings World!

====================================================
Console.WriteLine(sayHello.ToUpper());
Console.WriteLine(sayHello.ToLower());
=====================================================
출력
GREETINGS WORLD!
greetings world!

검색 문자열

string songLyrics = "You say goodbye, and I say hello";
Console.WriteLine(songLyrics.Contains("goodbye"));
Console.WriteLine(songLyrics.Contains("greetings"));
=====================================================
출력
True
False

정수 계산 살펴보기

int a = 18;
int b = 6;
int c = a + b;
Console.WriteLine(c);
int d = a - b;
Console.WriteLine(d);
int e = a * b;
Console.WriteLine(e);
int f = a / b;
Console.WriteLine(f);
=====================================================
출력
24
12
24
24

연산 순서 알아보기

int a = 5;
int b = 4;
int c = 2;
int d = a + b * c;
Console.WriteLine(d);
=====================================================
출력
13

int a = 5;
int b = 4;
int c = 2;
int d = (a + b) * c;
Console.WriteLine(d);
=====================================================
출력
18

int a = 5;
int b = 4;
int c = 2;
int d = (a + b) - 6 * c + (12 * 4) / 3 + 12;
Console.WriteLine(d);
=====================================================
출력
25

정수 전체 자릿수 및 한도 살펴보기

int a = 7;
int b = 4;
int c = 3;
int d = (a + b) / c;
int e = (a + b) % c;
Console.WriteLine($"quotient: {d}");
Console.WriteLine($"remainder: {e}");
=====================================================
출력
quotient: 3
remainder: 2

int max = int.MaxValue;
int min = int.MinValue;
Console.WriteLine($"The range of integers is {min} to {max}");
=====================================================
출력
The range of integers is -2147483648 to 2147483647

언더플로 또는 오버플로

int what = max + 3;
Console.WriteLine($"An example of overflow: {what}");
=====================================================
출력
(1,12): error CS0103: The name 'max' does not exist in the current context

double 형식 작업

double a = 5;
double b = 4;
double c = 2;
double d = (a + b) / c;
Console.WriteLine(d);
=====================================================
출력
4.5

double a = 19;
double b = 23;
double c = 8;
double d = (a + b) / c;
Console.WriteLine(d);
=====================================================
출력
5.25

double max = double.MaxValue;
double min = double.MinValue;
Console.WriteLine($"The range of double is {min} to {max}");
=====================================================
출력
The range of double is -1.79769313486232E+308 to 1.79769313486232E+308

double third = 1.0 / 3.0;
Console.WriteLine(third);
=====================================================
출력
0.333333333333333

10진 형식으로 작업

decimal min = decimal.MinValue;
decimal max = decimal.MaxValue;
Console.WriteLine($"The range of the decimal type is {min} to {max}");
=====================================================
출력
The range of the decimal type is -79228162514264337593543950335 to 79228162514264337593543950335

double a = 1.0;
double b = 3.0;
Console.WriteLine(a / b);

decimal c = 1.0M;
decimal d = 3.0M;
Console.WriteLine(c / d);
=====================================================
출력
0.333333333333333
0.3333333333333333333333333333

분기 및 루프, 조건문

if 문을 사용

int a = 5;
int b = 6;
if (a + b > 10)
    Console.WriteLine("The answer is greater than 10.");
=====================================================
출력
The answer is greater than 10.

if 와 else 함께 사용하기

int a = 5;
int b = 3;
int c = 4;
if ((a + b + c > 10) && (a == b))
{
    Console.WriteLine("The answer is greater than 10");
    Console.WriteLine("And the first number is equal to the second");
}
else
{
    Console.WriteLine("The answer is not greater than 10");
    Console.WriteLine("Or the first number is not equal to the second");
}
=====================================================
출력
The answer is not greater than 10
Or the first number is not equal to the second

루프를 사용하여 작업 반복 (while, do~while, for)

int counter = 0;
while (counter < 10)
{
  Console.WriteLine($"Hello World! The counter is {counter}");
  counter++;
}
=====================================================
출력
Hello World! The counter is 0
Hello World! The counter is 1
Hello World! The counter is 2
Hello World! The counter is 3
Hello World! The counter is 4
Hello World! The counter is 5
Hello World! The counter is 6
Hello World! The counter is 7
Hello World! The counter is 8
Hello World! The counter is 9

int counter = 0;
do
{
  Console.WriteLine($"Hello World! The counter is {counter}");
  counter++;
} while (counter < 10);
=====================================================
출력
Hello World! The counter is 0
Hello World! The counter is 1
Hello World! The counter is 2
Hello World! The counter is 3
Hello World! The counter is 4
Hello World! The counter is 5
Hello World! The counter is 6
Hello World! The counter is 7
Hello World! The counter is 8
Hello World! The counter is 9

for(int counter = 0; counter < 10; counter++)
{
  Console.WriteLine($"Hello World! The counter is {counter}");
}
=====================================================
출력
Hello World! The counter is 0
Hello World! The counter is 1
Hello World! The counter is 2
Hello World! The counter is 3
Hello World! The counter is 4
Hello World! The counter is 5
Hello World! The counter is 6
Hello World! The counter is 7
Hello World! The counter is 8
Hello World! The counter is 9

중첩 루프 만들기

for (int row = 1; row < 11; row++)
{
  Console.WriteLine($"The row is {row}");
}
=====================================================
출력
The row is 1
The row is 2
The row is 3
The row is 4
The row is 5
The row is 6
The row is 7
The row is 8
The row is 9
The row is 10

for (char column = 'a'; column < 'k'; column++)
{
  Console.WriteLine($"The column is {column}");
}
=====================================================
출력
The column is a
The column is b
The column is c
The column is d
The column is e
The column is f
The column is g
The column is h
The column is i
The column is j

for (int row = 1; row < 11; row++)
{
  for (char column = 'a'; column < 'k'; column++)
  {
    Console.WriteLine($"The cell is ({row}, {column})");
  }
}
=====================================================
출력
he cell is (1, a)
The cell is (1, b)
The cell is (1, c)
The cell is (1, d)
The cell is (1, e)
The cell is (1, f)
The cell is (1, g)
The cell is (1, h)
The cell is (1, i)
The cell is (1, j)
The cell is (2, a)
The cell is (2, b)
The cell is (2, c)
The cell is (2, d)
The cell is (2, e)
The cell is (2, f)
The cell is (2, g)
The cell is (2, h)
The cell is (2, i)
The cell is (2, j)
The cell is (3, a)
The cell is (3, b)
The cell is (3, c)
The cell is (3, d)
The cell is (3, e)
The cell is (3, f)
The cell is (3, g)
The cell is (3, h)
The cell is (3, i)
The cell is (3, j)
The cell is (4, a)
The cell is (4, b)
The cell is (4, c)
The cell is (4, d)
The cell is (4, e)
The cell is (4, f)
The cell is (4, g)
The cell is (4, h)
The cell is (4, i)
The cell is (4, j)
The cell is (5, a)
The cell is (5, b)
The cell is (5, c)
The cell is (5, d)
The cell is (5, e)
The cell is (5, f)
The cell is (5, g)
The cell is (5, h)
The cell is (5, i)
The cell is (5, j)
The cell is (6, a)
The cell is (6, b)
The cell is (6, c)
The cell is (6, d)
The cell is (6, e)
The cell is (6, f)
The cell is (6, g)
The cell is (6, h)
The cell is (6, i)
The cell is (6, j)
The cell is (7, a)
The cell is (7, b)
The cell is (7, c)
The cell is (7, d)
The cell is (7, e)
The cell is (7, f)
The cell is (7, g)
The cell is (7, h)
The cell is (7, i)
The cell is (7, j)
The cell is (8, a)
The cell is (8, b)
The cell is (8, c)
The cell is (8, d)
The cell is (8, e)
The cell is (8, f)
The cell is (8, g)
The cell is (8, h)
The cell is (8, i)
The cell is (8, j)
The cell is (9, a)
The cell is (9, b)
The cell is (9, c)
The cell is (9, d)
The cell is (9, e)
The cell is (9, f)
The cell is (9, g)
The cell is (9, h)
The cell is (9, i)
The cell is (9, j)
The cell is (10, a)
The cell is (10, b)
The cell is (10, c)
The cell is (10, d)
The cell is (10, e)
The cell is (10, f)
The cell is (10, g)
The cell is (10, h)
The cell is (10, i)
The cell is (10, j)