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  1. #include <stdio.h>
  2. #include <stdlib.h>
  3. #include <stdbool.h>
  4.  
  5. typedef struct {
  6.     int *items;
  7.     size_t len;
  8.     size_t capacity;
  9. } Stack;
  10.  
  11. Stack stack_new(void)
  12. {
  13.     Stack stack = {
  14.         .items = NULL,
  15.         .len = 0,
  16.         .capacity = 0
  17.     };
  18.  
  19.     return stack;
  20. }
  21.  
  22. void stack_push(Stack *stack, int value)
  23. {
  24.     if (stack->len == stack->capacity) {
  25.         size_t new_capacity = stack->capacity == 0
  26.             ? 4
  27.             : stack->capacity * 2;
  28.  
  29.         int *new_items = realloc(
  30.             stack->items,
  31.             new_capacity * sizeof(int)
  32.         );
  33.  
  34.         if (new_items == NULL) {
  35.             exit(EXIT_FAILURE);
  36.         }
  37.  
  38.         stack->items = new_items;
  39.         stack->capacity = new_capacity;
  40.     }
  41.  
  42.     stack->items[stack->len] = value;
  43.     stack->len++;
  44. }
  45.  
  46. bool stack_pop(Stack *stack, int *value)
  47. {
  48.     if (stack->len == 0) {
  49.         return false;
  50.     }
  51.  
  52.     stack->len--;
  53.     *value = stack->items[stack->len];
  54.  
  55.     return true;
  56. }
  57.  
  58. bool stack_peek(const Stack *stack, int *value)
  59. {
  60.     if (stack->len == 0) {
  61.         return false;
  62.     }
  63.  
  64.     *value = stack->items[stack->len - 1];
  65.  
  66.     return true;
  67. }
  68.  
  69. bool stack_is_empty(const Stack *stack)
  70. {
  71.     return stack->len == 0;
  72. }
  73.  
  74. size_t stack_len(const Stack *stack)
  75. {
  76.     return stack->len;
  77. }
  78.  
  79. void stack_free(Stack *stack)
  80. {
  81.     free(stack->items);
  82.  
  83.     stack->items = NULL;
  84.     stack->len = 0;
  85.     stack->capacity = 0;
  86. }
  87.  
  88. int main(void)
  89. {
  90.     Stack stack = stack_new();
  91.  
  92.     stack_push(&stack, 10);
  93.     stack_push(&stack, 20);
  94.     stack_push(&stack, 30);
  95.  
  96.     printf("len = %zu\n", stack_len(&stack));
  97.  
  98.     int value;
  99.  
  100.     if (stack_peek(&stack, &value)) {
  101.         printf("peek = %d\n", value);
  102.     }
  103.  
  104.     if (stack_pop(&stack, &value)) {
  105.         printf("pop = %d\n", value);
  106.     }
  107.  
  108.     if (stack_pop(&stack, &value)) {
  109.         printf("pop = %d\n", value);
  110.     }
  111.  
  112.     printf("len = %zu\n", stack_len(&stack));
  113.     printf("empty = %s\n",
  114.            stack_is_empty(&stack) ? "true" : "false");
  115.  
  116.     stack_free(&stack);
  117.  
  118.     return 0;
  119. }
Success #stdin #stdout 0s 5312KB
comments (?)
stdin 
Standard input is empty
stdout 
len = 3
peek = 30
pop = 30
pop = 20
len = 1
empty = false
https://ideone.com/9Gv8Xu
language:
C (gcc 8.3)
created:
1 day ago
visibility:
public

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