c – What is wrong with the algorithm?

Question:

The algorithm should return a two-dimensional array with a space-separated string (the same split(" ") from Python).

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

// Добавление char в конец массива char
void append(char* needed, char to_append) {
    int length = strlen(needed);
    needed[length] = to_append;
    needed[length+1] = '\0';
}


char** split(char* input) {
    int space_count = 0;

    // Считаем пробелы
    for (int i = 0; i < strlen(input); i++) {
        if (input[i] == ' ') {
            space_count++;
        }
    }

    // Указатель на указатель на char.
    char **splitted_input;
    // Выделяем память под массивы char
    splitted_input = (char**) malloc((space_count+1) * sizeof(*splitted_input));

    // Хранилище для текущей строки (перед пробелом)
    char word[100] = "";
    int current = 0;

    for (int i = 0; i < strlen(input); i++) {
        if (input[i] == ' ') {
            printf("NEW: [%d] = %s\n", current, word);
            splitted_input[current] = word;
            current++;
            // Обнуляем весь массив
            memset(word, 0, sizeof(word));
            continue;
        }

        // Если не пробел, то добавляем в конец word новый символ
        append(word, input[i]);
    }


    printf("NEW: [%d] = %s\n\n", current, word);
    // Добавляем текущую строку
    splitted_input[current] = word;

    for (int i = 0; i < space_count+1; i++) {
        printf("%s\n", splitted_input[i]);
    }


    // Еще не имею понятия, как здесь лучше освободить память splitted_input
    return splitted_input;
}



int main() {
    char input[20] = "hi everyone";

    char** need = split(input);

    return 0;
}

Outputs:

NEW: [0] = hi
NEW: [1] = everyone

everyone
everyone

I don't understand why splitted_input[0] is also equal to everyone

Answer:

Direct answer to the question: they both point to the same word .

Another problem: an array with pointers to a local variable is returned from the function.

Solution. For splitted_input[current] allocate memory for a new line where you copy the contents of word :

splitted_input[current] = strdup(word);