How Can I Use %nd in printf to Align Table Columns in C?

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The discussion focuses on creating a program that prints a table of powers in a well-formatted manner using the C programming language. The user seeks assistance with aligning the output using the printf function's formatting options, specifically the %nd specifier, which allows for controlling the width of printed integers. Key points include the importance of determining the maximum number of digits to ensure proper alignment, with suggestions to use %8d for an eight-character width. Additionally, the conversation suggests using a for loop instead of a while loop for better structure and efficiency, and emphasizes the need to adjust the placement of newline characters in the printf statements to ensure that each row of the table is printed correctly. Overall, the focus is on achieving a neatly formatted output for the powers table.
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my assignment is as follows:
write a programme printing a reasonably sized table of powers, in a nice format. using %nd in printf will write an integer in at least n charcaters. this facilitates printing tables with aligned columns.
here's my code:
Code:
#include <stdio.h>
#define STOP 10
int base()
{
  int input1;
  printf("enter the power to which you want to raise the base \n");
  printf("enter %d to stop \n", STOP);
  scanf("%d", &input1);
  return(input1);
}
main()
{
  int c,m=1,p=1,b=base();
    while (b<STOP){
      while(m<STOP){
        p=p*b;
        printf("\n %d", p);
        m+=1;
      }
      p=1;
      m=1;
      b+=1;
    }
}
now i want to align them in a table, so I am not sure how to use here %nd, any help would be appreciated.
 
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The "n" in "%nd" is a number, not the letter n.

For example "%3d" means print the number using at least 3 characters. So 5 would print as "space space 5", 25 as "space 5", "125" as "125".

"n" doesn't have to be a single digit. "%20d" would use 20 characters to print your number if you want to be really "spaced out".

There are more options if you need them, e.g. left justified numbers, printing "+" before positive numbers, adding zeros so 7 prints as "007", etc, etc. Look up "printf format modifiers" in your documentation (or on Google) for the details.
 
yes i know that it's a number, but i don't see how does it help me to biuld a table of powers.
i want that in the first row there will be only powers of 1, i.e:
1 2 3 4 5 6 7 8 9
1 4 9 16 36 49 64 81
...... etc
the problem is i don't see how %(number)d can help me?
 
Consider the largest number you're going to print. Maybe it's 8 digits? Then you'd use %8d to print each number, and each number would occupy 8 columns worth of space.

- Warren
 
loop quantum gravity, you might want to consider the for loop instead of the while here.
In addition, since base() is only used once there is no good reason to make it into a separate function.
 
Last edited:
loop quantum gravity said:
yes i know that it's a number, but i don't see how does it help me to biuld a table of powers.
i want that in the first row there will be only powers of 1, i.e:
1 2 3 4 5 6 7 8 9
1 4 9 16 36 49 64 81
...... etc
the problem is i don't see how %(number)d can help me?

To do that, you need to take the "\n" out of your existing printf() call, then add another printf("\n") statement in the right place, so you only output a new line after each complete row of numbers.

Changing "%d" to "%5d" or whatever will space the numbers neatly within each row.
 
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