Creating a Christmas tree programatically in c? - c

Question

I need help with creating a Christmas tree in C which varies based on user input.
Firstly, the user is prompted for the number of levels they want on the tree. E.g. First level "*", second level "***". Two stars are added every level.
Valid levels run between 4 and 10 inclusive. Anything less than 4 or greater than 10 is invalid, an error message will be displayed in the program output and the minimum level of the tree will also be displayed (4 levels).
The final part of the tree is done by adding a trunk with a width of 3 stars and a height of 2 stars.
This is my c program. It is incomplete and I have no idea how to move on. I am totally confused.
#include <stdio.h>
void main()
{
char choice;
int level, levelcount, star, starcount;
printf("Do you want to print a Christmas Tree (Y/N)?");
scanf_s(" %c", &choice);
if (choice == 'Y')
{
printf("How tall is your Christmas Tree (Level 4 to 10)?");
scanf_s("%d", &levelcount);
starcount = 1;
for (level = 1; level <= levelcount; level++)
{
for (star = 1; star <= starcount; star++)
{
printf("*");
}
printf("\n");
}
starcount += 2;
}
else if (choice == 'N')
{
printf("Merry Christmas and Goodbye!\n");
}
}

Answer 1

Firstly, your code is in C and not C++. If you're using C++ you'd use functions such as cin or cout but here you're using printf and scanf.
To create this tree you're going to have two sections. One part that deals with the main tree, and the other that deals with the trunk. In the code below I used a variable offset to calculate a certain number to determine the midpoint of the tree. Basically, each level has an odd number of stars. If you subtract the offset from the number of stars, you'll find the number at the mid-point. Starting from 3 the offset is 1. 3 - 1 = 2 which is the mid-point. For every two stars added to the level, the offset must go up by one.
To print the tree:
#include <stdio.h>
void main()
{
char choice;
int level, levelcount, star, starcount, offset;
printf("Do you want to print a Christmas Tree (Y/N)?");
scanf_s(" %c", &choice);
if (choice == 'Y')
{
printf("How tall is your Christmas Tree (Level 4 to 10)?");
scanf_s("%d", &levelcount);
//Check if level is within valid range
starcount = 1;
offset = 0;
if (levelcount < 4 || levelCount > 10)
{
//Prints default tree (4 levels)
for (level = 1; level <= 4; level++)
{
for(star = 1; star <= starcount; star++)
{
printf("*");
}
printf("\n");
//Adds two stars each level
starcount += 2;
offset += 1;
}
}
else
{
//Prints tree with custom levels
for (level = 1; level <= levelCount; level++)
{
for(star = 1; star <= starcount; star++)
{
printf("*");
}
printf("\n");
//Adds two stars each level
starcount += 2;
offset += 1;
}
}
//Finds out the mid-point of the tree
int midpoint = starcount - offset;
//Prints the trunk
printf("%*s%s\n", offset - 1, "***");
printf("%*s%s\n", offset - 1, "***");
}
else if (choice == 'N')
{
printf("Merry Christmas and Goodbye!\n");
}
}
For the trunk section, since it was at a fixed width of 3 stars and had only two levels, a loop wasn't exactly necessary but it would be good to include it. The %*s was a specific modifier to print some extra spaces to the left so it would be at the mid-point of the tree.
For more on padding with spaces in C check this answer by Bill the Lizard. One of the comments below the answer will show how I managed to print a certain number of spaces determined by the variable offset - 1.

Answer 2

#include <stdio.h>
int main()
{
int a,b,c,d,e,f,g,h,i,j,k,row;
printf("enter rows :");
scanf("%d",&row);
printf ("* * * * * *merry christmas* * * * * *\n\n");
for (a=1;a<=row;a++)
{
for (b=row;b>=a;b--)
{
printf(" ");
}
for (c=1;c<=a;c++)
{
printf("* ");
}
printf("\n");
}
for (d=1;d<=row-2;d++)
{
for (g=row-1;g>=1;g--)
{
printf(" ");
}
printf("* *\n");
}
return 0;
}