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Command-Line Syntax

The Push Swap program accepts integers as command-line arguments and outputs the sequence of operations needed to sort them.

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Basic Invocation

./push_swap [numbers...]

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Input Formats

Push Swap supports two different input formats, handled in main.c:15-35: 
./push_swap 3 2 1 5 4

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Multiple Arguments Format

When you pass numbers as separate arguments, each number is a distinct command-line parameter: 
./push_swap 42 -7 0 15
This format is processed by passing argv + 1 directly to ft_fill_stack() with flag 0 (main.c:31).

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Single String Format

When you pass numbers as a single quoted string, the program splits it internally: 
./push_swap "42 -7 0 15"
This format triggers ft_split() to parse the string by spaces (main.c:26), then processes the result with flag 1 to ensure proper memory cleanup.
Both input formats produce identical results. The single string format is useful when numbers come from variable expansion or script output.

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Understanding the Output

The program outputs a sequence of operations, one per line: 
./push_swap 3 2 1
Output
sa
rra
Each line represents one operation that transforms the stack. The operations are:
  • sa, sb, ss: Swap operations
  • pa, pb: Push operations
  • ra, rb, rr: Rotate operations
  • rra, rrb, rrr: Reverse rotate operations
For detailed information about each operation, see the Operations Reference.

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Output Interpretation

The output sequence represents the steps to sort the input numbers in ascending order:
  1. All numbers start in stack A
  2. Stack B starts empty
  3. Apply each operation in order
  4. Final result: sorted numbers in stack A, stack B empty

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Example Walkthrough

For input 3 2 1:
1

Initial State

Stack A: [3, 2, 1] (top to bottom)Stack B: []
2

After 'sa' (swap A)

Stack A: [2, 3, 1]Stack B: []
3

After 'rra' (reverse rotate A)

Stack A: [1, 2, 3] - Sorted!Stack B: []

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Edge Cases

The program handles several edge cases automatically:

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Empty or No Input

./push_swap
# No output, exits with status 0

./push_swap ""
# No output, exits with status 0
From main.c:22, the program exits silently when argc == 1 or when given an empty string.

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Already Sorted Input

./push_swap 1 2 3 4 5
# No output (no operations needed)
The is_stack_sorted() check in push_swap.c:85 detects pre-sorted input and skips sorting.

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Two Numbers

./push_swap 2 1
Output
sa
For exactly 2 numbers, the program uses a single swap operation if needed (push_swap.c:64-65).

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Next Steps

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