Why isnt the getc function giving me the right integer?

I was trying to learn how to write and read in a text file in C and I wrote this code:

#include <stdio.h>
int main(){
    FILE *pointer_to_text;
    pointer_to_text = fopen("kot.txt","w");
    fprintf(pointer_to_text,"%c",'c');
    int c = getc(pointer_to_text);
    printf("%d\n",c);
    fclose(pointer_to_text);
}

I open the file with fopen(), write a single char to it using fprintf() and then I want to back the value that I've just written.

However, getc() returns 0 instead of the character that I've just written.

I was just curious why it does that and what am I missing.

In the line

pointer_to_text = fopen("kot.txt","w");

you opened the file in write mode. If you want to create a new file (overwriting any existing file) but also want to be able to read from it, you should use the mode "w+" instead of "w".

Also, you cannot switch from writing to reading without an intervening call to fflush or call to a file positioning function (such as fseek or rewind). Otherwise, your program will invoke undefined behavior. See the documentation for fopen for further information.

After writing the file, the file position will be at the end of the file. Therefore, if you want to read what you have previously written, you must first call rewind to go back to the start of the file.

Obviously you can't read from a file you've opened for writing. Also keep in mind that IO should always be checked. Here's how you may do it:

#include <stdio.h>

int main(void) 
{
    FILE *file = fopen("kot.txt", "w");
    if (!file) {
        return 1;
    }
    if (fprintf(file, "%c", 'c') != 1) {
        return 2;
    }
    if (fclose(file) != 0) {
        return 3;
    }
    file = fopen("kot.txt", "r");
    if (!file) {
        return 4;
    }
    const int ch = getc(file);
    if (ch == EOF) {
        return 5;
    }

    printf("%c\n", ch);  // <- printf failures are typically not checked, since
                         // it's rare that you can recover from that.

    if (fclose(file) != 0) {
        return 6;
    }

    return 0;
}