Stack 구현 소스

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#include <stdio.h> #define SZ 5 int stack[5]; int top = -1; // check the stack is empty // it returns 1 if so, // returns 0 otherwise int isEmpty() { return (top == -1); } // check the stack is full // it returns 1 if so, // returns 0 otherwise int isFull() { // (SZ-1) is the last index of the stack return (top == (SZ - 1)); } // put the data d into the stack // if the stack is full, do nothing, just return void push(int d) { if (isFull() == 1) { return; } top++; // because the initial value of top is -1 stack[top] = d; // stack[++top] = d; the above two lines can be // written in one line. return; } // take out one item from the stack // returns -999 if the stack is empty. int pop() { if (isEmpty() == 1) { return -999; // -999 means the stack is empty. } top--; return stack[top + 1]; /* the above two lines mean the following. { int temp = stack[top]; top--; return temp; } */ } int main(void) { #if 0 // test case forf the full stack for (int i = 0; i <10; i++) { push(i); } printf("%d\n", pop()); #endif #if 0 // test case for the empty stack printf("%d \n", pop()); #endif #if 0 push(1); push(2); push(3); for (int i = 0; i < 3; i++) { printf("%d\n", pop()); } #endif return 0; }