I am having some trouble starting my program. I'm new to this. I have done some research and found some resources, but I have trouble applying it to the code. It is mostly based on pointers and structures.
I mainly need help with learning how to store the data in the struct, and how to initialize everything.
The program is supposed to find the frequency of characters in a file. I need to use dynamic memory allocation. And use a dynamically allocated array of pointers to store the characters and frequencies. I am supposed to use malloc() to allocate the array and realloc() to increase the size of the array to insert more elements. But I have no idea how to do this.
The program uses these functions-
• charInCFStruct:which returns the index of charfreq struct which has the char c stored in its member variable next. If none of the charfreq structs contains c then it has to return -1.
• printCFStruct: Prints the contents of all of the charfreq structs.
• freeCFStruct: Frees all of the charfreq structs and then frees the pointer to the structs.
Down below is what I know is right so far. I thought it would be easier to start again from there. I am not asking for code exactly, just some help with the topics I need to do this, and a push in the right direction. Thank you!
#include <stdio.h>
#include <stdlib.h>/*
* struct for storing a char and the number of times it appears in a provided text */
struct charfreq
{
int count;
char next;
};
typedef struct charfreq charfreq;
/*
* Returns the index of charfreq struct which has the char c stored in its member variable next.
* If none of the charfreq structs contains c then it returns -1.
*/
int charInCFStruct(charfreq **cfarray, int size, char c){
}
/*
* Prints the contents of all of the charfreq structs.
*/
void printCFStruct(charfreq **cfarray, int size){
}
/*
* Frees all of the charfreq structs and then frees the pointer to the structs.
*/
void freeCFStruct(charfreq **cfarray, int size){
}
int main(void)
{
charfreq **cfarray;
FILE *inputfile;
char next;
int size = 10; /* used initial value of 10 but any positive number should work */
int i = 0;
int pos;
/* open file to read from */
inputfile = fopen("chars.txt", "r");
if(inputfile == NULL)
printf("chars.txt could not be opened. Check that the file is in the same directory as you are running this code. Ensure that its name is chars.txt.\n\n");
/* allocate space for pointers to char frequency structs */
cfarray = (charfreq**)malloc(size*sizeof(charfreq*));
/* read in chars until the end of file is reached */
while(fscanf(inputfile, "%c", &next) != EOF){
/* fill in code to fill structs with data being read in */
/* call to increase space after changing size */
cfarray = realloc(cfarray,size*sizeof(charfreq*));
}
/* print out char frequency structs */
printCFStruct(cfarray,i);
/* free all char frequency structs */
freeCFStruct(cfarray,i);
/* close the file we opened earlier */
fclose(inputfile);
return 0;
}
