View difference between Paste ID: 1dTgV10Q and E9qaJGMG

 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
 #include <ctype.h>
 void add_symbol(char **line, char symb, int len)
 {
     int new_size = (len+2)*sizeof(char); //+1 for symbol, +2 for \0
     char *line_copy = (char*) malloc(new_size);
     strcpy(line_copy, *line);
     line_copy[len] = symb;
     line_copy[len+1] = '\0';
     *line = (char *) realloc(*line, new_size);
     strcpy(*line, line_copy);
     free(line_copy);
 }
 int main()
 {
     char input;
     char *final_line = (char*) malloc(sizeof(char)*1);
     final_line[0] = '\0';
     while ((input = getchar()) != '0') //input != '0'
     {
         if (isalpha(input))
             add_symbol(&final_line, input, strlen(final_line));
         else if (input != '\n') //\n, \r and other != EOF
             printf("Invalid input: %c\n", input); //
     }
     printf("Final line: \"%s\"\n", final_line);
     free(final_line);
     return 0;
 }