Populating an array of chars with strings dynamically

Question

I'm new to C and i'm trying to store some strings inside a 2D array of chars.Here's what i have:

char strArray[100][100];
char input[100];
scanf("%s",&input);
strArray[i] = input; //this is where i get the incompatible types assignment error

As shown in the comment i get an incompatible types in assignment error.Do i need to use an array of char *strArray[100][100] ? Aren't strArray and input both of the same type (char [])? The one's 1D and the other is 2D obviously but i just didn't specify the 2nd dimension in the assignment since each string is stored in a new line. What am i doing wrong?

scanf("%s",&input); -> scanf("%s",input); , strArray[i] = input; -> strcpy(strArray[i], input); — Osiris
– Osiris, Commented Nov 7, 2018 at 22:38
@Osiris that's the same thing right? the array works as a pointer but & works too right? — Stelios Papamichail
– Stelios Papamichail, Commented Nov 7, 2018 at 22:39
input decays to a pointer to char while &input is a pointer to char[100]. So it is not the same, and %s expects a pointer to char. — Osiris
– Osiris, Commented Nov 7, 2018 at 22:39
Oh i see, and as for the strcpy() function, is that the only way for this "procedure" to be done? Can it also be done with pointers? — Stelios Papamichail
– Stelios Papamichail, Commented Nov 7, 2018 at 22:41
You can loop over the array and copy it element wise. Or you can use memcpy. You can not copy arrays with the = operator. — Osiris
– Osiris, Commented Nov 7, 2018 at 22:42

Swordfish · Accepted Answer · 2018-11-07 23:14:17Z

2

You'd have to use strcpy():

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

int main(void)
{
    char strArray[100][100];
    char input[100];
    scanf("%s", input);
    strcpy(strArray[0], input);
}

But never, really: never! use scanf() with "%s" without limiting the number of characters to read (field width):

 scanf("%99s", input);

edited Nov 7, 2018 at 23:14

answered Nov 7, 2018 at 22:41

Swordfish

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1 Comment

Stelios Papamichail Over a year ago

That's an awesome tip, i had no idea i could limit the number of chars that the user can enter by specifying a number between % and s within scanf. Awesome

aokellermann · Accepted Answer · 2018-11-07 22:41:07Z

0

You can use strcpy() to copy each char in input to strArray[i]. In this case you would use

strcpy(strArray[i], input);

answered Nov 7, 2018 at 22:41

aokellermann

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Comments

Stephan Lechner · Accepted Answer · 2018-11-07 22:46:18Z

0

In C, you cannot assign arrays in the sense of char input1[100], input2[100]; input1 = input2. You can just copy the contents using, for example, strcpy for strings or memcpy for arbitrary memory chunks.

So you'd have to write strcpy(strArray[i],input), provided that i is an integral value between 0 and 99 in your case.

Further, you'll have to omit the & in scanf("%s",&input) (i.e. write scanf("%s",input)), because input already decays to a pointer to char.

edited Nov 7, 2018 at 22:46

answered Nov 7, 2018 at 22:40

Stephan Lechner

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