How store each string of getline() inside a (dynamic) array of strings?

Question

I'm using the getline() function to get every line of stdin. Every line is a string with different length:

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

int main() {
    char *line = NULL;
    size_t foo = 0;
    ssize_t reader;

    while ((reader = getline(&line, &foo, stdin)) != -1) { // %zu of reader is length of line
        printf("%s", line);
    }

    free(line);
    return 0;
}

In every iteration, line is a string and is containing the current line. How can I take each string-line and store it inside an array? There are several things I have tried but none of them worked or they just lead to memory access failure :(

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I hope my question is clear? If it's not, please tell me and I will change it!

Answer 1

Unless you know up front how many lines to expect, then you will have to allocate the array dynamically, eg:

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

int main() {
    char *line = NULL;
    size_t foo = 0;
    ssize_t reader;
    int result = 0;

    int numlines = 0, maxlines = 10;
    char **lines = malloc(sizeof(char*) * maxlines);

    if (!lines) {
        printf("error allocating array\n");
    }
    else {
        while ((reader = getline(&line, &foo, stdin)) != -1) { // %zu of reader is length of line
            printf("%s", line);

            if (numlines == maxlines) {
                maxlines *= 2; // <-- or use whatever threshold makes sense for you
                char **newlines = realloc(lines, sizeof(char*) * maxlines);
                if (!newlines) {
                    printf("error reallocating array\n");
                    result = -1;
                    break;
                }
                lines = newlines;
            }

            lines[numlines] = line;
            ++numlines;

            line = NULL;
            foo = 0;
        }
        free(line); // <-- in case getline() or realloc() failed...

        // use lines up to numlines as needed

        // free lines
        for(int i = 0; i < numlines; ++i) {
            free(lines[i]);
        }
        free(lines);
    }

    return result;
}