#include <stdio.h>
#include <stdlib.h>

void write_file(char const* filename, char const* contents) {
    FILE* fp = fopen(filename, "w");
    for(int i = 0; contents[i] != '\0'; i++) {
        char char_to_write = contents[i];
        fputc(char_to_write, fp);  // write one character
    }
    fclose(fp);
}

int main(int argc, char* argv[]) {
    char const contents[] = "ABC"; // string literal ("▒") implies an ending '\0'.

                                   // IOW, the '\0' is added by the compiler automatically
                                   // to a string literal (i.e., with double quotes).
                                   //
                                   // Null terminator ('\0') only has special meaning with
                                   // C string library functions, e.g., strlen(…),
                                   // strcat(…), printf("…"), and so forth.
                                   //
                                   // String literal is a char* and cannot have bytes >127.
                                   //
                                   // String literal can't be used for uchar with bytes
                                   // >127.
    char const contents[] = { 'A', 'B', 'C', '\0' };
    write_file("a.txt", contents);
    return EXIT_SUCCESS;
}