Left-pad printf with spaces

int space = 40;
printf("%*s", space, "Hello");

This statement will reserve a row of 40 characters, print string at the end of the row (removing extra spaces such that the total row length is constant at 40). Same can be used for characters and integers as follows:

printf("%*d", space, 10);
printf("%*c", space, 'x');

This method using a parameter to determine spaces is useful where a variable number of spaces is required. These statements will still work with integer literals as follows:

printf("%*d", 10, 10);
printf("%*c", 20, 'x');
printf("%*s", 30, "Hello");

Hope this helps someone like me in future.

I use this function to indent my output (for example to print a tree structure). The indent is the number of spaces before the string.

void print_with_indent(int indent, char * string)
{
    printf("%*s%s", indent, "", string);
}

If you want the word "Hello" to print in a column that's 40 characters wide, with spaces padding the left, use the following.

char *ptr = "Hello";
printf("%40s\n", ptr);

That will give you 35 spaces, then the word "Hello". This is how you format stuff when you know how wide you want the column, but the data changes (well, it's one way you can do it).

If you know you want exactly 40 spaces then some text, save the 40 spaces in a constant and print them. If you need to print multiple lines, either use multiple printf statements like the one above, or do it in a loop, changing the value of ptr each time.