I'm trying to read the following type of input

2
string1
string2

where the first line indicates the amount of strings following below, and the strings are all of (some) same length. Next, I'd like to print these strings in my program, which I was thinking of doing as follows.

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

void print_string_array(char** a, int size){
    for (int i=0; i<size; i  ){
        printf("%s\n", a[i]);
    }
}

int main()
{
    int n;
    scanf("%d", &n);
    char* s;
    scanf("%s", s);
    int l = strlen(s);
    char input[n][l];
    strcpy(s, input[0]);
    for (int i = 1; i < n; i  ) {
        scanf("%s", s);
        strcpy(s, input[i]);
    }
    print_string_array(input, n);
}

But I get the following warnings and error.

main.c: In function ‘main’:
main.c:24:24: warning: passing argument 1 of ‘print_string_array’ from incompatible pointer type [-Wincompatible-pointer-types]
   24 |     print_string_array(input, n);
      |                        ^~~~~
      |                        |
      |                        char (*)[(sizetype)(l)]
main.c:5:32: note: expected ‘char **’ but argument is of type ‘char (*)[(sizetype)(l)]’
    5 | void print_string_array(char** a, int size){
      |                         ~~~~~~~^

Segmentation fault (core dumped)

Why isn't my array input recognized as a char** type? And how would I go about fixing this without removing the general properties of my current program (for example, adaptability to any length of input strings)?

EDIT:

I've corrected some mistakes from not having coded in C for years (which may be a war crime from what I've seen in the comments):

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

void print_string_array(char** a, int size){
    for (int i=0; i<size; i  ){
        printf("%s\n", a[i]);
    }
}

int main(){
    int n;
    scanf("%d", &n);
    char s[100]; // large enough buffer 
    scanf("%s", s);
    int l = strlen(s);
    char input[n][l 1]; //  1 to leave room for ‘\0’ character?
    strcpy(input[0], s);
    for (int i=1; i<n; i  ){
        scanf("%s", input[i]);
    }
    print_string_array(input, n);
    for (int i=0; i<n; i  ){
        free(input[i]);
    } 
    free(input);
}

But I still get some errors and warnings which I would like to solve.

main.c: In function ‘main’:
main.c:22:24: warning: passing argument 1 of ‘print_string_array’ from incompatible pointer type [-Wincompatible-pointer-types]
   22 |     print_string_array(input, n);
      |                        ^~~~~
      |                        |
      |                        char (*)[(sizetype)(n)]
main.c:5:32: note: expected ‘char **’ but argument is of type ‘char (*)[(sizetype)(n)]’
    5 | void print_string_array(char** a, int size){
      |                         ~~~~~~~^

Segmentation fault (core dumped)

Starting with the warnings, obviously I change the type of a from char** to something else. However, should I really give it the type char (*)[(sizetype)(n)]?? Also, there's the problem of segmentaion fault which is happening somewhere in the for loop.

CodePudding user response：

Besides the problems in your code that are explained in the comments.

input is a char* that points to an array in memory that is of size n*l and not a char**, which is a pointer to a char*.

You would need to allocate an array of char*[] and then add each char* pointer that you get from scanf to that array.

CodePudding user response：

Maybe this will help you out. It shows an example of dynamic string allocation

char buffer[101];
printf("Enter your name: ");
// Stores the name into auxiliary memory
scanf(" 0[^\n]", buffer);
// Creates a dynamic string
char* name = (char *) malloc(strlen(buffer)   1);
//or use char* name = strdup(buffer) as pointed out by @Cheatah in the comments
// Sets the value
strcpy(name, buffer); 

printf("Your name is %s", name);
// Frees the memory
free(name);

CodePudding user response：

The Variable Length Array input[n][l 1] does not need to be free'd.
The input[n][l 1] array is not a pointer to pointer **a. There are differences in the memory arrangement and they are not compatible.
void print_string_array( int size, int len, char (*a)[len]){ gives the compiler the dimensions of the VLA so the function can access it correctly.
scanf("