# argv-array API

The argv-array API allows one to dynamically build and store NULL-terminated lists. An argv-array maintains the invariant that the `argv` member always points to a non-NULL array, and that the array is always NULL-terminated at the element pointed to by `argv[argc]`. This makes the result suitable for passing to functions expecting to receive argv from main(), or the run-command API.

The string-list API (documented in string-list.h) is similar, but cannot be used for these purposes; instead of storing a straight string pointer, it contains an item structure with a `util` field that is not compatible with the traditional argv interface.

Each `argv_array` manages its own memory. Any strings pushed into the array are duplicated, and all memory is freed by argv_array_clear().

## Data Structures

`struct argv_array`

  A single array. This should be initialized by assignment from `ARGV_ARRAY_INIT`, or by calling `argv_array_init`. The `argv` member contains the actual array; the `argc` member contains the number of elements in the array, not including the terminating NULL.

## Functions

`argv_array_init`

  Initialize an array. This is no different than assigning from `ARGV_ARRAY_INIT`.

`argv_array_push`

  Push a copy of a string onto the end of the array.

`argv_array_pushl`

  Push a list of strings onto the end of the array. The arguments should be a list of `const char *` strings, terminated by a NULL argument.

`argv_array_pushf`

  Format a string and push it onto the end of the array. This is a convenience wrapper combining `strbuf_addf` and `argv_array_push`.

`argv_array_pushv`

  Push a null-terminated array of strings onto the end of the array.

`argv_array_pop`

  Remove the final element from the array. If there are no elements in the array, do nothing.

`argv_array_clear`

  Free all memory associated with the array and return it to the initial, empty state.

`argv_array_detach`

  Disconnect the `argv` member from the `argv_array` struct and return it. The caller is responsible for freeing the memory used by the array, and by the strings it references. After detaching, the `argv_array` is in a reinitialized state and can be pushed into again.