How to add a string from user input into an array dynamically in C?-CodePudding

I want to create a simple C program where, inside a loop, when the user inputs a string, the string automatically gets added to an array. I'm lost on how to do that at runtime. Any help would be appreciated.

Edit: For clarification, here, 10 is the max size of the array. I was thinking of initializing the array with a number and then expanding that size (probably by a multiplier) when it reaches the max size (which is 10 in this case).

Edit2: More specifically, I want it to be so that the first iteration adds a string to the array, then the second iteration adds another inputted string to the array, and so on.

For now my code looks like this:

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

int main() {
    char* strings[10];
    char *input_str;
    printf("enter a string: ")
    
    strings = malloc(sizeof(char)*10); //not sure if this is required but included anyway
    
    //run a loop here to keep adding the input string 
    fgets((char)input_str, 1024, stdin);
    
}

CodePudding user response：

char* strings[10];

Notice that strings is a non resizable array of ten pointers to char, so it is not useful for dynamic allocation when you don't know the number of elements before hand.

I will use realloc over a char ** and the modulo operator to detect when to realloc, something like:

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

#define MULTIPLE 10

int main(void)
{
    char **strings = NULL;
    char str[1024];
    size_t size = 0;

    while (fgets(str, sizeof str, stdin))
    {
        if ((size % MULTIPLE) == 0)
        {
            char **temp = realloc(strings, sizeof *strings * (size   MULTIPLE));

            if (temp == NULL)
            {
                perror("realloc");
                exit(EXIT_FAILURE);
            }
            strings = temp;
        }
        strings[size] = malloc(strlen(str)   1);
        if (strings[size] == NULL)
        {
            perror("malloc");
            exit(EXIT_FAILURE);
        }
        strcpy(strings[size], str);
        size  ;
    }
    for (size_t i = 0; i < size; i  )
    {
        printf("%s", strings[i]);
        free(strings[i]);
    }
    free(strings);
    return 0;
}