How to input two strings separated by new line in C

Question

How can I input 2 strings which are separated by a new line?

My Problem:

First I need to give how many strings I need to get and then I need to get those strings then display it.

I tried this:

Code:

#include <stdio.h>
#include <string.h>

int main()
{

    int n,i = 0;
    scanf("%d", &n);
    char arr[n][100];
    for(int i = 0; i < n; i++)
    {
        scanf("%[^\n]s", arr[i]);
    }

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

    return 0;
}

My Input is :

2 I am
Aravind

My Output is:

I am
þ

First Line I got correct one but second line it shows some garbage value. Help me to solve this.

Some programmer dude · Accepted Answer · 2018-07-17 12:29:42Z

7

You have two major problems:

The "%[" format ends with the closing "]", there should be no "s" at the end.
The "%[" format doesn't skip leading space, like that newline which will be present after the first line you read.

Both these issues can be easily solve by using fgets to read whole lines instead.

answered Jul 17, 2018 at 12:29

Some programmer dude

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3 Comments

Aravind Ekan Over a year ago

Hi is there any other method apart from fgets?

Some programmer dude Over a year ago

@AravindEkan To read lines using standard C functions only, the best solution is fgets. You can use scanf (and family) but it becomes much more complex, and without a field-width limiter can also easily cause buffer overflows.

chux Over a year ago

3rd problem, no width limit. "%[^\n]" is then akin to gets(). Yes, better to use fgets().

Nathalia Soragge · Accepted Answer · 2018-07-18 03:43:56Z

You already have suggestions to not use scanf. However, if you 'must' use scanf then you can consider the following approach:

For dynamic memory allocation you should use malloc
the newline character stays in the stdin and hence needs to be flushed or handled/ignored

Here is the updated code.

int main()
{
    int n,i = 0;
    scanf("%d", &n);

    scanf("%*[\n]"); 
    /*this will read the \n in stdin and not store it anywhere. So the next call to 
     * scanf will not be interfered with */

    char **inputs;
    inputs = malloc(n * sizeof(char *));

    for (i = 0; i < n; i++)
    {
       inputs[i] = malloc(100 * sizeof(char));
    }


    for(i = 0; i < n; i++)
    {
        scanf("%*[\n]");
        scanf("%100[^\n]", inputs[i]);
    }

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

    return 0;
}

new_learner · Accepted Answer · 2018-07-17 13:00:52Z

-2

use gets(arr[i]) instead of scanf.

answered Jul 17, 2018 at 13:00

new_learner

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1 Comment

Some programmer dude Over a year ago

Never ever use gets. It's a dangerous function, and has therefore been removed from the C standard (and was deprecated long before).

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