C Programming Made Easy: Start Building Systems From Scratch

#include <stdio.h>
#include <stdlib.h>

int main() {
    // 栈
    int stack[100];
    int top = -1;

    // 解析用户输入
    char input[100];
    printf("Enter an expression: ");
    scanf("%s", input);

    // 遍历输入字符串
    for (int i = 0; input[i] != '\0'; i++) {
        char token = input[i];

        // 操作数压入栈中
        if (isdigit(token)) {
            int num = token - '0';
            push(stack, &top, num);
        }

        // 操作符出栈并进行计算
        else if (isOperator(token)) {
            int op2 = pop(stack, &top);
            int op1 = pop(stack, &top);
            int result = calculate(op1, op2, token);
            push(stack, &top, result);
        }
    }

    // 输出计算结果
    printf("Result: %d\n", stack[top]);

    return 0;
}