1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 | #include <stdio.h>
#include <stdlib.h>
#include <stdbool.h>
#include <assert.h>
char* make_divider(char divider_char, int num_repetitions) {
// Return a new string consisting of «num_repetitions» divider_char's followed by a '\n'.
// char divider[10000]; // BAD!!! We can't predict how large num_repetitions may be.
// char* new_buffer = malloc(«NUMBER_OF_THINGS» * sizeof(*new_buffer));
// └─┬──┘ └─────────────────┬────────────────────┘
// │ number of bytes in the buffer you want to create
// │
// allocates memory on the heap and returns address to that buffer.
char* divider = malloc((num_repetitions + 2) * sizeof(*divider));
// └───────┬───────────┘ └─────────────────┬────────────────────┘
// # of chars (including '\n') plus '\0' # of bytes required to store one char
// POPULATE the string
for(int i = 0; i < num_repetitions; i++) {
divider[i] = divider_char;
}
divider[num_repetitions] = '\n'; // newline, as promised
divider[num_repetitions + 1] = '\0'; // null terminator -- always needed when building
// a string from scratch in memory.
// PROBLEM #1: You cannot return a statically allocated array¹.
// PROBLEM #2: We don't know how large the `divider` buffer needs to be.
//
// ¹ In this or any other obvious way. There are always tricks.
return divider;
}
int main(int argc, char* argv[]) {
// CREATE divider. This allocates memory on the HEAP.
char* divider = make_divider('-', 80);
// PRINT message.
printf("\n");
printf("I woke up this morning feeling SUPER!!!\n");
printf("%s", divider);
printf("Where's the butler? Hand me the butter!\n\n");
// FREE memory for divider.
free(divider);
return EXIT_SUCCESS;
}
/* vim: set tabstop=4 shiftwidth=4 fileencoding=utf-8 noexpandtab: */
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