How many chars can be in a char array?

Question

#define HUGE_NUMBER ???

char string[HUGE_NUMBER];
do_something_with_the_string(string);

I was wondering what would be the maximum number that I co

Answer 1

Declaring arbitrarily huge arrays to avoid buffer overflows is bad practice. If you really don't know in advance how large a buffer needs to be, use malloc or realloc to dynamically allocate and extend the buffer as necessary, possibly using a smaller, fixed-sized buffer as an intermediary.

Example:

#define PAGE_SIZE 1024  // 1K buffer; you can make this larger or smaller

/**
 * Read up to the next newline character from the specified stream.
 * Dynamically allocate and extend a buffer as necessary to hold
 * the line contents.
 *
 * The final size of the generated buffer is written to bufferSize.
 * 
 * Returns NULL if the buffer cannot be allocated or if extending it
 * fails.
 */
 char *getNextLine(FILE *stream, size_t *bufferSize)
 {
   char input[PAGE_SIZE];  // allocate 
   int done = 0;
   char *targetBuffer = NULL;
   *bufferSize = 0;

   while (!done)
   {
     if(fgets(input, sizeof input, stream) != NULL)
     {
       char *tmp;
       char *newline = strchr(input, '\n');
       if (newline != NULL)
       {
         done = 1;
         *newline = 0;
       }
       tmp = realloc(targetBuffer, sizeof *tmp * (*bufferSize + strlen(input)));
       if (tmp)
       {
         targetBuffer = tmp;
         *bufferSize += strlen(input);
         strcat(targetBuffer, input);
       }
       else
       {
         free(targetBuffer);
         targetBuffer = NULL;
         *bufferSize = 0;
         fprintf(stderr, "Unable to allocate or extend input buffer\n");

       }
     }
   }