how to properly indent and format a source code?

Hello.

I want to learn how to indent and format properly my source codes. I have found this online:

https://en.wikipedia.org/wiki/Indent_style
GNU Coding Standards: Formatting

Here is a source code that I wrote where I was criticized that it is not correctly formated:

http://cboard.cprogramming.com/c-pro...ml#post1248158

Code:

---

#include <stdio.h>
 
int main()
{
    int i,j;
    int array1[3][3]= {{0,0,0},{0,12,36},{0,32,56}} ;
    int sqr[3][3];
 
    /* multiplication part */
    for(i=0;i<3;i++)
    {
          for(j=0;j<3;j++){
                              sqr[i][j]=array1[i][0]*array1[0][j]+array1[i][1]*array1[1][j]+array1[i][2]*array1[2][j];
                          }
    }
 
 
 
    /* here is the printing part */
    for(i=0;i<3;i++)
    {
        for(j=0;j<3;j++){
                        printf("%d\t",sqr[i][j]);
                        }
        printf("\n");
    }
    return 0;
}

---

1) What does it mean to properly indent a code? >> I think that this is pretty clearly explained in the wikipedia article and I think that I already do that right, even in the example

2) What does it mean to properly indent a code? >> Does it mean two empty lines between code? What more?

Thank you.

A corrected version:

Code:

---

#include <stdio.h>
 
int main()
{
    int i,j;
    int array1[3][3]= {{0,0,0},{0,12,36},{0,32,56}} ;
    int sqr[3][3];
 

    /* multiplication part */
    for(i=0;i<3;i++)
    {
        for(j=0;j<3;j++){
                          sqr[i][j]=array1[i][0]*array1[0][j]+array1[i][1]*array1[1][j]+array1[i][2]*array1[2][j];
                        }
    }


    /* here is the printing part */
    for(i=0;i<3;i++)
    {
        for(j=0;j<3;j++){
                        printf("%d\t",sqr[i][j]);
                        }
        printf("\n");
    }


    return 0;
}

---

Look at the indent style wiki page you posted.

Tell me which indent style your code matches up with..

I think that the one I used is the Allman style.

https://en.wikipedia.org/wiki/Indent_style#Allman_style

I see it now. For the code more on the right I used the Whitesmiths_style..

https://en.wikipedia.org/wiki/Indent...tesmiths_style

EDIT: Here it is all just in Allman indent style:

Code:

---

#include <stdio.h>
 
int main()
{
    int i,j;
    int array1[3][3]={{0,0,0},{0,12,36},{0,32,56}};
    int sqr[3][3];
 
 
    /* multiplication part */
    for(i=0;i<3;i++)
    {
        for(j=0;j<3;j++)
        {
            sqr[i][j]=array1[i][0]*array1[0][j]+array1[i][1]*array1[1][j]+array1[i][2]*array1[2][j];
        }
    }
 
 
    /* here is the printing part */
    for(i=0;i<3;i++)
    {
        for(j=0;j<3;j++)
        {
            printf("%d\t",sqr[i][j]);
        }
        printf("\n");
    }
 
 
    return 0;
}

---

Is it better to stick to one indent style? I suppose yes.

How about the formatting?

Quote:

---

Is it better to stick to one indent style?

---

It is better to be consistent. Your indentation in your first post is very inconsistent, your inner loop indentation differs from the outer loop indentation.

Jim

Your previous post has no style at all.
Sometimes the starting brace is on a line by itself, sometimes not.
Sometimes you indent by 4, sometimes by an arbitrary number of spaces.
It's idiotic.

Post number three of this thread contains a corrected version.

So the formatting is about number of spaces between a code starts on a line and between spaces between lines of different type of code?

Quote:

---

So the formatting is about number of spaces between a code starts on a line and between spaces between lines of different type of code?

---

Partially yes. There are also differences as to where the braces are located, use of tabs versus spaces, and many other aspects

As I said the biggest part of "your" indentation style should be consistency. Don't use spaces in some places and tabs in another, don't use 3 spaces in some locations and some other number of spaces in another, don't indent braces in one instance but not another, etc. Also how you use blank lines and whitespace to separate items should be consistent. One of my pet peeves is no/inconsistent spacing within formulas, and excessively long lines. For example:

Code:

---

/////// POOR /////////
        for(j=0;j<3;j++)
        {
            sqr[i][j]=array1[i][0]*array1[0][j]+array1[i][1]*array1[1][j]+array1[i][2]*array1[2][j];
        }
/////// Better IMO.
        for(j = 0; j < 3; j++)
        {
            sqr[i][j] = array1[i][0] * array1[0][j] + array1[i][1]
                                              * array1[1][j] + array1[i][2]
                                              * array1[2][j];
        }

---

And don't forget to use parentheses to insure that your doing the operations in the correct order, instead of relying only on operator precedence.


Jim

You could also make your array initialization look much nicer by using a bit of extra whitespace.

This:

Code:

---

int array1[3][3]={{0,0,0},{0,12,36},{0,32,56}};

---

... could look something like this:

Code:

---

int array1[3][3] = { { 0,  0,  0 },
                    { 0, 12, 36 },
                    { 0, 32, 56 } };

---

Since the position of the numbers on the screen now correlate to their positions within the array, visually finding the value at a particular spot is much easier. This also makes updating the initialization (if you change the size of either/both dimensions) easier.

Thank you all.

Here is the current version:

Code:

---

#include <stdio.h>

int main()
{
    int i,j;
    int array1[3][3] = { { 0,  0,  0 },
                        { 0, 12, 36 },
                        { 0, 32, 56 } };
    int sqr[3][3];


    /* multiplication part */
    for(i=0;i<3;i++)
    {
        for(j=0;j<3;j++)
        {
            sqr[i][j]=array1[i][0]*array1[0][j]
                    +array1[i][1]*array1[1][j]
                    +array1[i][2]*array1[2][j];
        }
    }


    /* here is the printing part */
    for(i=0;i<3;i++)
    {
        for(j=0;j<3;j++)
        {
            printf("%d\t",sqr[i][j]);
        }
        printf("\n");
    }


    return 0;
}

---

How to recognize a case for using spaces and for using tabs? In my text editor one tab equals eight spaces.

I have a better experience of using spaces, because with tabs in different editors the text is just somewhere else (more on the right or left). Maybe that in different editors one tab equals to different number of spaces.

Quote:

---

How to recognize a case for using spaces and for using tabs? In my text editor one tab equals eight spaces.

---

Most text editors can be setup to use a different number of spaces, and to place these spaces in the file instead of the tab character. A lot of people recommend that you configure your editors to change tabs to spaces, to help preserve the formatting no matter what editor you use.

Don't forget about things like:

Code:

---

// Instead of:
    for(i=0;i<3;i++)
// Use whitespace to highlight the operators.
    for(i = 0; i < 3; i++)

---

After all you wouldn't write a letter without using any whitespace, would you?


Jim

Quote:

---

Originally Posted by nerio

How to recognize a case for using spaces and for using tabs? In my text editor one tab equals eight spaces.

---

I prefer to just use spaces as I think it is easier to be consistent that way. If you do want to use tab characters, then make sure that they are used for the basic indentation only, not for pretty alignment of text.