Yologger's Blog

# 헤더파일

#include <stdio.h>

# gcc 컴파일러

$ pwd
/Library/Developer/CommandLineTools/usr/bin

$ ls
gcc

$ vim main.c
$ ls
main.c

$ gcc main.c
$ ls
a.out  main.c

$ ./a.out
Hello World

# 표준입출력 라이브러리

컴파일러가 설치된 경로의 include 디렉토리에 존재한다.

#include <stdio.h>

# printf()

void main() {
    
    int age = 32;
    char* name = "Paul";
    
    printf("Hello World \n");
    printf("My name is %s \n", name);
    printf("My age is %d \n", age);
    
    return;
}

# scanf()

#include <stdio.h>
#include <stdbool.h>

void main() {
    
    int a;
    float b;
    
    scanf("%d %f", &a, &b);

    printf("%d %f", a, b);
    
    return;
}

# 변수

# 정수

#include <stdio.h>

void main() {

    short a = 30;
    int b = 30;
    long c = 30;
    
    printf("%d \n", a);
    printf("%d \n", b);
    printf("%d \n", c);

    return;
}

# 실수

#include <stdio.h>

void main() {

    float height = 176.3;
    double weight = 70.3;
    printf("%f \n", height);
    printf("%f \n", weight);

    return;
}

# 문자

#include <stdio.h>
#include <stdbool.h>

void main() {

    char alphabet = 'a';
    
    printf("%c \n", alphabet);
    
    return;
}

# 문자열

# bool

stdbool.h를 포함시켜야 한다.

#include <stdio.h>
#include <stdbool.h>

void main() {
    
    bool isMarried = false;
    if (isMarried) {
        printf("is married.");
    } else {
        printf("is not married.");
    }
    return;
}

# 형변환

void main() {

    double height = 176.3;
    int _height = (int)height;
    
    printf("%d \n", _height);   // 176
    
    return;
}

# 상수

#include <stdio.h>

void main() {

    const int DB_CONNECTION = 100;
    
    printf("%d \n", DB_CONNECTION);
    
    return;
}

# 반복문

# while

#include <stdio.h>
#include <stdbool.h>

void main() {
    
    int idx = 0;
    
    while (idx < 10) {
        printf("Hello \n");
        idx ++;
    }
    
    return;
}

# for

#include <stdio.h>
#include <stdbool.h>

void main() {
    
    for (int i=0; i<10; i++) {
        printf("Hello \n");
    }
    
    return;
}

# 조건문

#include <stdio.h>
#include <stdbool.h>

void main() {
    
    bool isMarried = true;
    
    if (isMarried) {
        printf("She is married. \n");
    } else {
        printf("She is not married. \n");
    }
    
    return;
}

#include <stdio.h>
#include <stdbool.h>

void main() {
    
    bool age = 40;
    
    if (age < 20) {
        printf("She is teen. \n");
    } else if (age > 20 && age < 65){
        printf("She is adult. \n");
    } else {
        printf("She is senior. \n");
    }
    
    return;
}

# 함수

#include <stdio.h>
#include <stdbool.h>

int sum(int a, int b) {
    return a+b;
}

void main() {
    
    int result = sum(30, 50);
    printf("%d", result);
    
    return;
}

# DEFINE

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