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.

score 7 · Answer 1 · answered Jul 17 '18 at 12:29

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 '18 at 12:29

Some programmer dude

400,186
35
402
621

Hi is there any other method apart from fgets? – Aravind Ekan Jul 17 '18 at 12:51
1

@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. – Some programmer dude Jul 17 '18 at 12:54
3rd problem, no width limit. `"%[^\n]"` is then akin to `gets()`. Yes, better to use `fgets()`. – chux - Reinstate Monica Jul 17 '18 at 14:59

score 1 · Accepted Answer · edited Jul 18 '18 at 03:43

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;
}

score -2 · Answer 3 · answered Jul 17 '18 at 13:00

-2

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

answered Jul 17 '18 at 13:00

new_learner

131
10

2

Never *ever* use `gets`. [It's a dangerous function](https://stackoverflow.com/questions/1694036/why-is-the-gets-function-so-dangerous-that-it-should-not-be-used), and has therefore been removed from the C standard (and was deprecated long before). – Some programmer dude Jul 17 '18 at 13:05

How to input two strings separated by new line in C

3 Answers3