如何在c的文本文件中重写该单词频率计数器程序？

Question

Here we see the program which computes how frequent each word of text file is present. After some small corrections it becomes to work perfectly for sufficiently small files. I wanted to use it for large text file, but get an error "Segmentation fault". The reason is that there is an initialization of array

 char p[1000][512], 

which is so small for large text (if I understand correctly, it can save only 1000 words (which in general may coincide)). If I try to enlarge the dimension of p, I also get this error (there cannot be arrays larger than 2000*2000 on my computer).

Could the code above be modified in order for opening large text files? If yes, how to do that? Could You write the code which modifies it?

Answer 1

Consider allocating your array on head using malloc .

When you declare your array like char char p[1000][512] , it allocates 512 * 1000 (about 512 Kb) on stack. Stack size is insufficient for large files. When you allocate your memory using malloc, you ask operating system to give you some additional memory in heap.

So, instead of your code you should do like

typedef char * string_t;
string_t * stringsArray = malloc(sizeof(string_t) * NUM_STRINGS_TO_ALLOCATE);
for (size_t i = 0; i < STRINGS_COUNT; ++i)
   stringsArray[i] = malloc(sizeof(char) * NUM_CHARS_PER_STRING);

don't forget to free allocated memory after using it, like:

for (size_t i = 0; i < STRINGS_COUNT; ++i)
   free(stringsArray[i]);
free(stringsArray);