Member Avatar for Sarang07

I want to stop the \t tab after 5 spaces, How do i do that?

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Short answer: the C language only emits the ASCII tab character (0x09). How many spaces that appears as is decided by the program that displays the output (terminal, pager, editor). To get "tabs every 5 spaces" you must either change the consumer's tab stops, convert tabs to spaces, or stop using \t and output fixed padding from your program.

Practical options, from easiest to most robust:

  • Change the viewer/pager/editor. Many pagers let you set tab stops (for example less -x5). Terminal emulators often have a tab-stop setting or a tabs utility. See the general behaviour of the tab character here: Tab character on Wikipedia.

  • Convert tabs to spaces after the program prints. On Unix-like systems expand -t 5 file > out will replace tabs with the number of spaces needed to hit 5-column stops; this is handy for files or pipelines. See expand documentation: expand(1) manual.

  • Change your program to produce spaces (recommended when you need exact layout). Replace \t at output time with the number of spaces needed to reach the next 5-column stop. The following routine does that: 

#include <stdio.h>

void print_with_tabwidth(const char *s, int tabwidth) {
    int col = 0;
    for (; *s; ++s) {
        if (*s == '\t') {
            int spaces = tabwidth - (col % tabwidth);
            while (spaces--) { putchar(' '); ++col; }
        } else {
            putchar(*s);
            if (*s == '\n') col = 0; else ++col;
        }
    }
}

Notes tied to the thread: was correct that the display decides tab width. ’s pointer to terminal settings pointed in a useful direction but stty itself does not change visual tab stops. and offered quick hacks; they can work but are brittle compared with expanding tabs or formatting fields explicitly. If you changed a setting and saw no effect, confirm which program is rendering the output (terminal vs pager vs editor) and verify the output actually contains \t (use hexdump/od or pipe through expand) before changing code.

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Member Avatar for ithelp

Not sure whether you can do it , but check stty manual.

Member Avatar for gerard4143

You could try something like below...I generally don't like the solution but it works for some situations

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

#define t "     "

int main(int argc, char**argv)
{		
	fprintf(stdout, "this\tis\ta\ttest", stdout);	
	exit(EXIT_SUCCESS);
}
Edited by gerard4143 because: n/a
Member Avatar for Ancient Dragon

You could try something like below...I

That should produce an error because \' ' is not a valid escape sequence.

If you don't like the default spacing then don't use tabs. Do something like this: printf("%-20s", "Hello World"); where the text string will be left-justified in a field 20 characters wide, right-side padded with spaces.

Edited by Ancient Dragon because: n/a
Member Avatar for Narue

C doesn't specify tab stops, only tab characters. It's up to the program consuming those characters to interpret the character with a certain tab stop length, just like it's up to the same program to accurately print the 'Q' character. Translation: change the properties of whatever program is displaying those tabs to use a five character tab stop explicitly. Most likely this will be your shell, for command line programs that send output to stdout.

Edited by Narue because: n/a
Member Avatar for Sarang07

It does not work for me.

It is as the default. I modified it but it does not worked.

Help.

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