What is the output?

void main()
{
if(-100)
 printf("Negative number");
else
 printf("Positive number");
}

void main()
{
 if(1 || 0)
  printf("C Programming");
 else
  printf("learn C");
}

void main()
{
 int x= 5;
 if(x < 1);
  printf("Hello");
  printf("Hi");
}

void main()
{
 int x = 5;
 if (x < 1)
  printf("hello");
 if (x == 5)
  printf("hi");
 else
  printf("no");
}

void main()
{
 int x = 5;
 if (true);
  printf("hello");
}

void main()
{
 int x = 0;
 if (x == 0)
  printf("hi");
 else
  printf("how are u");
  printf("hello");
}

void main()
{
    int ch;
    printf("enter a value between 1 to 2:");
    scanf("%d", &ch);
    switch (ch)
    {
       case 1:
       printf("1\n");
       default:
       printf("2\n");
    }
}
//1 is input

void main()
{
    int ch;
    printf("enter a value between 1 to 2:");
    scanf("%d", &ch);
    switch (ch)
    {
        case 1:
        printf("1\n");
        break;
        printf("Hi");
        default:
        printf("2\n");
    }
}
//2 is input

void main()
{
    int x = 0;
    if (x++)
        printf("true\n");
    else if (x == 1)
        printf("false\n");
}