问字符串到换行符的动态内存分配函数

EN

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

//Returns dynamic allocated string(read until the '\n' aka. newline character)
char* input_string_line()
{   char *s,*aux,c;                     //*s(string pointer),*aux(auxiliary string pointer),c(the characters that are read)
    int len;                            //len(actual length of the string)
    s=malloc(sizeof(char));             //firstly, allocation memory for 1 byte(8 bites), for the null character
    if (!s)                             //verification if the memory can be allocated, if not possible then the program exits
    {   printf("ERROR: Memory allocation failure (string).\n");
        exit(EXIT_FAILURE); }
    s[0] = 0;                           //NULL character for string ending
    len = 0;                            //the length of the string at the beginning is 0(without considering the NULL character at the end)
    while ((c = getchar()) != '\n')     //reading character by character until newline
    {   aux = realloc(s, len + 2);      //reallocation memory for the next read character in a new auxiliary string(same as the old string, this time having memory for a new character to be added)
        if (!aux)                       //verification if the reallocation can succed: if not possible then the program exits
        {   free(s);
            printf("ERROR: Memory allocation failure (auxiliary string).\n");
            exit(EXIT_FAILURE); }
        else s = aux;                   //if succeded, then the string becomes the auxiliary string
        s[len] = c;                     //the character with the [len] index will be assigned the value of the read character
        s[len+1] = 0;                   //NULL character for string ending
        len++;  }                       //length increments by one each time a new character is added to the string
    return s;
    free(s);                        
}

int main()
{ printf("%s",input_string_line());
return 0;}