A dummy example using `strdup` as a C-function that returns an allocated `char
*` that needs to be free'd:
proc free(p: pointer) {.importc: "free", header: "<stdlib.h>".}
proc strdup(c: cstring) : cstring {.importc: "strdup", header:
"<stdlib.h>".}
proc main() =
var foo: cstring = "abcdefg"
# strdup in C does a memory allocation
# I just use this to emulate a proc that return an allocated pointer
var bar = strdup(foo)
echo bar
free(bar)
when isMainModule:
main()
Run
Let's check with Valgrind that there is no memory leak :
* compile with `nim c -d:useMalloc --gc:arc --debugger=native simpletest.nim`
* run `valgrind ./simpletest`.
==9640== Memcheck, a memory error detector ==9640== Copyright (C) 2002-2017,
and GNU GPL'd, by Julian Seward et al. ==9640== Using Valgrind-3.17.0 and
LibVEX; rerun with -h for copyright info ==9640== Command: ./simpletest
==9640== abcdefg ==9640== ==9640== HEAP SUMMARY: ==9640== in use at exit: 0
bytes in 0 blocks ==9640== total heap usage: 3 allocs, 3 frees, 1,048 bytes
allocated ==9640== ==9640== All heap blocks were freed -- no leaks are possible
==9640== ==9640== For lists of detected and suppressed errors, rerun with: -s
==9640== ERROR SUMMARY: 0 errors from 0 contexts (suppressed: 0 from 0)
