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| /**
| * @数字计算方法
| * @author (zyk)
| * @returns
| */
|
| // 运算符
| const operators = ['+', '-', '*', '/', '(', ')'];
| // 运算符优先级
| const priority = {
| ')': 30,
| '*': 20,
| '/': 20,
| '+': 10,
| '-': 10,
| '(': 0,
| };
| // 获取小数点位数
| const calcPos = (num) => (num.toString().indexOf('.') > -1 ? num.toString().split('.')[1].length : 0);
| // 忽略小数点转为整数
| const parseNum = (num) => parseInt(num.toString().replace('.', ''));
|
| const FC = {
| // 加
| _add: (n1, n2) => {
| const p1 = calcPos(n1);
| const p2 = calcPos(n2);
| const m = Math.pow(10, Math.max(p1, p2));
| return (FC._mul(n1, m) + FC._mul(n2, m)) / m;
| },
| add: (...nums) => {
| let result = nums[0];
| for (let i = 1; i < nums.length; i++) result = FC._add(result, nums[i]);
| return result;
| },
| // 减
| _sub: (n1, n2) => FC.add(n1, -n2),
| sub: (...nums) => {
| let result = nums[0];
| for (let i = 1; i < nums.length; i++) result = FC._sub(result, nums[i]);
| return result;
| },
| // 乘
| _mul: (n1, n2) => {
| const p1 = calcPos(n1);
| const p2 = calcPos(n2);
| const m = Math.pow(10, p1 + p2);
| return (parseNum(n1) * parseNum(n2)) / m;
| },
| mul: (...nums) => {
| let result = nums[0];
| for (let i = 1; i < nums.length; i++) result = FC._mul(result, nums[i]);
| return result;
| },
| // 除
| _div: (n1, n2) => {
| const p1 = calcPos(n1);
| const p2 = calcPos(n2);
| const m = Math.pow(10, p2 - p1);
| return FC.mul(parseNum(n1) / parseNum(n2), m);
| },
| div: (...nums) => {
| let result = nums[0];
| for (let i = 1; i < nums.length; i++) result = FC._div(result, nums[i]);
| return result;
| },
| // 表达式计算
| calc: (expression) => {
| // 转化为表达式数组
| operators.map((op) => (expression = expression.split(op).join(`,${op},`)));
| const eArr = expression.split(',').filter((item) => item !== '');
|
| // 中缀转后缀
| const ops = [];
| const result = [];
| for (const item of eArr) {
| // 是操作符
| if (operators.includes(item)) {
| // 操作符栈为空 直接入栈
| if (ops.length === 0) ops.push(item);
| else {
| // 左括号 直接入栈
| if (item === '(') ops.push(item);
| // 右括号 匹配括号
| else if (item === ')') {
| let top = ops.pop();
| while (top !== '(') {
| result.push(top);
| top = ops.pop();
| }
| }
| // 加减乘除
| else if (priority[item] > priority[ops[ops.length - 1]]) ops.push(item);
| else {
| while (
| ops.length > 0 &&
| priority[item] <= priority[ops[ops.length - 1]]
| ) {
| const top = ops.pop();
| result.push(top);
| }
| ops.push(item);
| }
| }
| }
| // 是数字
| else {
| result.push(item);
| }
| }
| // 多余运算符推入结果栈
| while (ops.length > 0) result.push(ops.pop());
|
| // 后缀表达式计算
| const nums = [];
| // let r = 0;
| for (const item of result) {
| // 是运算符
| if (operators.includes(item)) {
| const num2 = nums.pop();
| const num1 = nums.pop();
| if (item === '+') nums.push(FC._add(num1, num2));
| if (item === '-') nums.push(FC._sub(num1, num2));
| if (item === '*') nums.push(FC._mul(num1, num2));
| if (item === '/') nums.push(FC._div(num1, num2));
| } else {
| nums.push(item);
| }
| }
| return nums[0];
| },
| };
|
| export default FC;
|
|
