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// numbers.c
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include "numbers.h"

// [...] Funktionssignaturen

Number* init_number(char* data){
    Number* number = malloc(sizeof(Number));
    if (number == NULL){
        return NULL;
    }
    int length = strlen(data);

    number->data = malloc(length * sizeof(char));
    if (number->data == NULL){
        free(number);
        return NULL;
    }
    strcpy(number->data, data);
    number->length = length;

    return number;
}

bool number_add(Number* n1, const Number* n2){
    if (n1 == NULL || n2 == NULL){
        return false;
    }

    for (int i = n2->length - 1, j = n1->length - 1; i >= 0; i--, j--){
        int r = ctoi(n1->data[j]) + ctoi(n2->data[i]);
        align(n1, j, r);
    }
    return true; 
}

void align(Number* number, const int index, const int n){
    number->data[index] = itoc(n % 10);

    if (n >= 10){
        int r = ctoi(number->data[index - 1]) + (n / 10);
        if (r >= 10 && index - 1 <= 0){
            number->length++;
            number->data = realloc(number->data, number->length * sizeof(char));

            number->data[number->length - 1] = '\0';
            for (int i = number->length - 2; i > 0; i--){
                char temp = number->data[i - 1];
                number->data[i - 1] = number->data[i];
                number->data[i] = temp;
            }
        }

        if (r >= 10){
            align(number, index - 1, r);
        } else {
            number->data[index - 1] = itoc(r);
        }
    }
}

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// main.c
#include <stdio.h>
#include <stdlib.h>
#include "numbers.h"

#define COUNT 100

char* NUMBERS[COUNT] = {
    // [...]
    "17423706905851860660448207621209813287860733969412", /* die Zahl bei der der Fehler passiert */
   // [...]
};

int main(void){
    Number* r = init_number(NUMBERS[0]);

    for (int i = 1; i < COUNT; i++){
        Number* n = init_number(NUMBERS[i]);
        number_add(r, n);

        free_number(n);
        n = NULL;
    }
    free_number(r);

    return EXIT_SUCCESS;
}

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char* data = "1234";
char* target = malloc(strlen(data) * sizeof(char)); //entspricht Zeile 14+16
strcpy(data, target); //Zeile 21