#include <stdio.h>

int main01(void)
{
    int a, b;
    a = 10;
    b = 30;
    int i = a == b;//==是判断两个变量是否相等
    i = 3 < 5 && 3 == 2;
    i = 3 <= 5 && 3 != 2;

    i = 1 == 3 || 3 < 7;

    i = !(3 > 5 || (a = b));

    i = !a;

    a = 0;
    i = !a;

    i = !(a != b);





    printf("i = %d\n", i);
    return 0;
}

//int main()一个函数在C语言里面，如果只是空（），代表这个函数可以有参数，也可以没有参数
//int main(void)如果是(void)，就是明确的表达，没有任何参数

int main03()
{
    int a = 3;
    int b = 5;
    if (a != b && b > 10)
    {
        printf("hello world\n");
    }


    if (0)
    {
        printf("true\n");
    }
    else
    {
        printf("false\n");
    }
    return 0;
}

int main()
{
    int a = 0;
    int b = 0;
    printf("please input a:");
    scanf("%d", &a);
    printf("please input b:");
    scanf("%d", &b);

    if (a > b)
    {
        printf("a = %d\n", a);
    }else
    {
        printf("b = %d\n", b);
    }
    return 0;
}

#include <stdio.h>

int main01(void)
{
    int a = 0;
    int b = 0;
    char c = 0;

    printf("please input a:");
    scanf("%d", &a);
    getchar();//通过getchar这个函数将之前输入a时候用户按的回车键先收到

    printf("please input operator:");
    scanf("%c", &c);//通过键盘输入一个字符

    printf("please input b:");
    scanf("%d", &b);

    if (c == ‘+‘)
    {
        printf("a + b = %d\n", a + b);
    }else if (c == ‘-‘)
    {
        printf("a - b = %d\n", a - b);
    }else if (c == ‘*‘)
    {
        printf("a * b = %d\n", a * b);
    }else if (c == ‘/‘)
    {
        if (b == 0)
        {
            printf("error\n");
        }else
        {
            printf("a / b = %d\n", a / b);
        }
    }else
    {
        printf("error\n");
    }
    return 0;
}

int main02()
{
    int i = 1;
    switch (i)
    {
    case 0:
        printf("i = 0\n");
        break;//跳出switch的复合语句块
    case 1:
        printf("i = 1\n");
        break;
    case 2:
        printf("i = 2\n");
        break;
    case 3:
        printf("i = 3\n");
        break;
    case 4:
        printf("i = 4\n");
        break;
    default://如果有所条件都不满足，那么执行default语句
        printf("error\n");
    }
    return 0;
}

int main03()
{
    int i = 10;
    if (i == 0)
    {
        printf("i = 0\n");
    }
    else if (i == 1)
    {
        printf("i = 1\n");
    }
    else if (i == 2)
    {
        printf("i = 2\n");
    }
    else if (i == 3)
    {
        printf("i = 3\n");
    }
    else if (i == 4)
    {
        printf("i = 4\n");
    }
    else
    {
        printf("error\n");
    }
    return 0;
}

int main04(void)
{
    int a = 0;
    int b = 0;
    char c = 0;

    printf("please input a:");
    scanf("%d", &a);
    getchar();//通过getchar这个函数将之前输入a时候用户按的回车键先收到

    printf("please input operator:");
    scanf("%c", &c);//通过键盘输入一个字符

    printf("please input b:");
    scanf("%d", &b);

    switch (c)
    {
    case ‘+‘:
        printf("a + b = %d\n", a + b);
        break;
    case ‘-‘:
        printf("a - b = %d\n", a - b);
        break;
    case ‘*‘:
        printf("a * b = %d\n", a * b);
        break;
    case ‘/‘:
        switch(b)
        {
        case 0:
            printf("error\n");
            break;
        default:
            printf("a / b = %d\n", a / b);
        }
        break;
    default:
        printf("error\n");
    }
    return 0;
}

int main()
{
    goto end;//无条件的跳转到一个标号去执行
    int a = 0;
    int b = 0;
    scanf("%d", &a);
    scanf("%d", &b);

//    int c;
//    if (a > b)
//    {
//        c = a;
//    }
//    else
//    {
//        c = b;
//    }

    int c = (a > b) ? a : b;

    printf("c = %d\n", c);

    end://标号
    printf("end\n");

    return 0;

}