removing last character from strings in two dimensional array

Question

How can I remove the '\n' from each string in this array?

I know that I can do something like this for a simple C-String, but I failed at using it in this case

cmd[strcspn(cmd, "\n")] = '\0';

I am also not sure if that would be the propper way or not.

The String will never contain any space or \n in the middle. They are also of a static length (6).

#include <stdlib.h>

unsigned char cmd[][6] = { 
    {"r123\n"},
    {"r999\n"},
    {"l092\n"},
    {"l420\n"}};

void main(void) {
    int i;

    for(i = 0; i < (sizeof(cmd) / sizeof(cmd[0])); i++) {
        printf("%s\n", cmd[i]);
    }   
}

You should provide more information to get more useful answer. Will the length of these strings be always 5 (6 with '\0') ? Do you want to remove '\n' also if it's in the middle of this string ? ... — LihO
– LihO, Commented May 24, 2012 at 8:46
I concur with LihO. If you want a general solution for the problem, the you should say so. On the other hand, if you want a solution that works for a very specific case (e.g. always 5 strings, always length 5, ...) then you should specify the details so we know what we can use. — penelope
– penelope, Commented May 24, 2012 at 9:02
Okay, I will do that next time, promised. I got the solution for this case already. The strings have static length and there won't be any whitespace or '\n' character in the middle of the string. — Joel Bodenmann
– Joel Bodenmann, Commented May 24, 2012 at 9:15

penelope · Accepted Answer · 2012-05-24 09:21:27Z

2

Just do it by hand, it's easy!

If it's guaranteed to be only the last char in every word, and it's guaranteed to be there, than like this:

for (i = 0; i < elem_number; ++i){
    cmd[i][strlen(cmd[i])-1] = 0;
}

If, on the other hand, you are unsure how many whitespace characters there will be at the end, but you know they will only be there at the end (there might be 0 in this case!) than this:

for (i = 0; i < elem_number; ++i){
    for (j = 0; cmd[i][j] != 0; ++j){
        if (isspace(cmd[i][j]))
             cmd[i][j] = 0;
     }
}

Voila!

If there will be whitespaces in the middle, then you have to define the desired behaviour: cut only the trailing whitespaces, cut the string in many little ones, or something completely different.

Oh, and one other sidenote: everyone else seems to be using char = '\0'. In C, '\0' and 0 are equivalent, i.e. if ('\0' == 0) { ... } evaluates to true.

Sidenote 2: I used elem_number because I did not know if the number of elements is a parameter or hardcoded / know in advance. Substitute with what is appropriate.

edited May 24, 2012 at 9:21

answered May 24, 2012 at 8:50

penelope

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2 Comments

LihO Over a year ago

Although '\0' and 0 are equal, you should use '\0' in this case. With '\0' you explicitly say "I'm using terminating NULL character here."

penelope Over a year ago

I think it's such common knowledge that it's equal, it has more of an individual style choice by now.

acraig5075 · Accepted Answer · 2012-05-24 09:03:33Z

1

Setting a character in a char array to \0 will truncate the string at that character. So in your example setting the 5th character will do the job.

cmd[i][4] = '\0';

If the intended string can be less than 4 in length then don't hard-code to 4 but rather strlen(cmd[i])-1

edited May 24, 2012 at 9:03

answered May 24, 2012 at 8:41

acraig5075

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1 Comment

Joel Bodenmann Over a year ago

that seems pretty fast forward :D

Some programmer dude · Accepted Answer · 2012-05-24 08:43:37Z

0

Maybe you can use strrchr? Use in a loop if the string may contain several linebreaks.

answered May 24, 2012 at 8:43

Some programmer dude

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Comments

BLUEPIXY · Accepted Answer · 2012-05-24 08:57:09Z

-1

    for(i = 0; i< sizeof(cmd)/sizeof(unsigned char[6]);i++)
        *strchr(cmd[i], '\n') = '\0';

answered May 24, 2012 at 8:57

BLUEPIXY

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5 Comments

penelope Over a year ago

this is a non-general solution with the string length hardcoded, without any written explanation for the exact special case it is intended for. Also, the Q author seems to be a little bit inexperienced, I don't think he would benefit much with a copy-paseable solution without an explanation.

Joel Bodenmann Over a year ago

This it shall be! Thank you very much!

penelope Over a year ago

unsigned char[6] ? The author didn't specify it that's just an example array to demonstrate with or if it will always be [6]. Oh, and, my mistake, array size, not str length

BLUEPIXY Over a year ago

origin unsigned char cmd[][6]

penelope Over a year ago

I know where you get it from, it's just that I find general solutions working on a broad spectrum of example codes better than one targeted for a very specific, narrow problem. Spamming the comment section now.

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