Formatting help for command prompt output in C

Question

#include <stdio.h>
#include <stdlib.h>

int power(int base, int power){
    int result, i;
    result = 1;
    for (i=0; i < power; i++){
        result *= base;
    }/*for*/
    return result;
}/*power*/

int main (){
    int n = 0;

    int exponent = 0;
    while(n < 10){
        int answer = power(2, n);
        float neganswer = 1.0 / (power(2,n));

        printf("%d %d %g\n", exponent, answer, neganswer);

        exponent++;
        n++;
    }/*while*/
    return EXIT_SUCCESS;

}/*main*/

When this program runs, the 2nd function goes from 1 to 512, which pushes the rest of the columns are moved 2 to the right. How would I go about lining up these columns? Thanks.

Yu Hao · Accepted Answer · 2013-09-24 02:46:09Z

3

You can change your printf format to:

printf("%d %3d %10g\n", exponent, answer, neganswer);

This will format the argument to the specific width:

0   1          1
1   2        0.5
2   4       0.25
3   8      0.125
4  16     0.0625
5  32    0.03125
6  64   0.015625
7 128  0.0078125
8 256 0.00390625
9 512 0.00195312

answered Sep 24, 2013 at 2:46

Yu Hao

123k50 gold badges252 silver badges305 bronze badges

Sign up to request clarification or add additional context in comments.

Comments

chux · Accepted Answer · 2013-09-24 12:23:03Z

2

Not to take away from the all ready provided fine 2 answers, but many options are available with printf().

// Nicely aligned with decimal point in the same place
// #  : Alternate form always prints `.`
// -  : Left justify the output.
// .* : Determine width from the next parameter which is `n`.
printf("%d %4d %#-.*f\n", exponent, answer, n, neganswer);
0    1 1.
1    2 0.5
2    4 0.25
3    8 0.125
4   16 0.0625
5   32 0.03125
6   64 0.015625
7  128 0.0078125
8  256 0.00390625
9  512 0.001953125

edited Sep 24, 2013 at 12:23

answered Sep 24, 2013 at 3:37

chux

158k17 gold badges160 silver badges311 bronze badges

Comments

sunysen · Accepted Answer · 2013-09-26 05:51:05Z

C string that contains the text to be written to stdout. It can optionally contain embedded format specifiers that are replaced by the values specified in subsequent additional arguments and formatted as requested.

A format specifier follows this prototype: [see compatibility note below]

%[flags][width][.precision][length]specifier 

int main (){
    int n = 0;

    int exponent = 0;
    while(n < 10){
        int answer = power(2, n);
        float neganswer = 1.0 / (power(2,n));

        //modify printf("%d %d %g\n", exponent, answer, neganswer);
        printf("%d %4d %12g\n", exponent, answer, neganswer);

        exponent++;
        n++;
    }/*while*/
    return EXIT_SUCCESS;

}/*main*/

more about printf function, please refer to the following link

http://en.cppreference.com/w/c/io/fprintf

Paul · Accepted Answer · 2013-09-26 01:33:58Z

0

Take a look at my simple library: libtprint , the code there is quite easy to understand and you should get some basic ideas how to format columns with printf ().

Hope it helps !

answered Sep 26, 2013 at 1:33

Paul

1,3689 silver badges16 bronze badges

Comments

haccks · Accepted Answer · 2013-10-15 20:55:02Z

0

Try this

    float neganswer = 1.0f / (power(2,n));

    printf("%d %3d %f\n", exponent, answer, neganswer);

answered Oct 15, 2013 at 20:55

haccks

107k28 gold badges181 silver badges274 bronze badges

Collectives™ on Stack Overflow

Formatting help for command prompt output in C

5 Answers 5

Comments

Comments

Comments

Comments

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

5 Answers 5

Comments

Comments

Comments

Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Related