Marshal an array of strings from C# to C code using p/invoke

Question

I need to pass an array of C# strings into C code

Example C code

void print_string_array(const char** str_array, int length){
    for (int i = 0; i &         


        

Answer 1

Your second attempt is quite close. Try the following:

string[] foo = {"testing", "one", "two", "three"};  
IntPtr[] s_array = new IntPtr[foo.Length];

for(int i = 0; i < foo.Length; ++i) 
{
    s_array[i] = Marshal.StringToHGlobalAnsi(foo[i])
}
GCHandle gH = GCHandle.Alloc(s_array, GCHandleType.Pinned);
print_string_array( gH.AddrOfPinnedObject(), s_array.Length);
gH.Free();
for(int i = 0; i < foo.Length; ++i) 
{
    Marshal.FreeHGlobal(s_array[i])
}

[DllImport(my_C_dll, CharSet = CharSet.Ansi)]
private static extern int print_string_array(IntPtr sa, int length);