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

int main(int argc, char* argv[]) {
    
    int num_chars = 5;
    char* s = malloc(sizeof(*s) * num_chars);
    // sizeof(*s) gives you the number of bytes per char 
    // num_chars is the number of char (elements) in the new array.
    //
    // This will be on the HEAP (segment of memory).
    
    s[0] = 'Y';
    s[1] = 'o';
    s[2] = 'p';
    s[3] = 'e';
    s[4] = '\0';

    // BAD
    // char* s = (char*) malloc(sizeof(*s) * num_chars);  // no unnecessary cast
    // char* s = malloc(sizeof(char) * num_chars);        // use sizeof(expr)

    // Note:  sizeof(..) does not access or evaluate the expression so there
    //        is no problem using it before it is initialized.

    printf("%s\n", s);

    // FIXME:  This is a leak because we haven't called free(…).
    
    return EXIT_SUCCESS;
}
/*
==20653== HEAP SUMMARY:
==20653==     in use at exit: 5 bytes in 1 blocks
==20653==   total heap usage: 1 allocs, 0 frees, 5 bytes allocated
==20653==
==20653== 5 bytes in 1 blocks are definitely lost in loss record 1 of 1
==20653==    at 0x4A06A2E: malloc (vg_replace_malloc.c:270)
==20653==    by 0x4005C8: main (malloc_intro_with_leak.c:7)
==20653==
==20653== LEAK SUMMARY:
==20653==    definitely lost: 5 bytes in 1 blocks
==20653==    indirectly lost: 0 bytes in 0 blocks
==20653==      possibly lost: 0 bytes in 0 blocks
==20653==    still reachable: 0 bytes in 0 blocks
==20653==         suppressed: 0 bytes in 0 blocks
*/
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