An array-backed stack in C

A fixed-capacity stack with push and pop.

#define CAP 64

struct Stack {
    int items[CAP];
    int top;
};

void push(struct Stack *s, int value) {
    if (s->top < CAP)
        s->items[s->top++] = value;
}

int pop(struct Stack *s) {
    return s->top > 0 ? s->items[--s->top] : -1;
}

How it works

1. top tracks the next free slot.
2. push writes then advances top.
3. pop retreats top and returns the value.

Keywords and builtins used here

• Stack
• if
• int
• pop
• push
• return
• struct
• void

The run, in numbers

Lines

15

Characters to type

222

Tokens

86

Three-star pace

100 tpm

At the three-star pace of 100 tokens a minute, this run takes about 52 seconds.

Type this snippet

Step 4 of 5 in Lists & stacks, step 9 of 20 in Data structures & algorithms.

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