用C语言编写一个计算器，要求能进行加减乘除，乘方和带括号的运算

Question

 

Answer 1

#include <stdio.h>
#include <stdlib.h>
#include <math.h>
#define INIT_STRING_SIZE 100
#define True 1
#define False 0
int saved_class[4] = { 0, 0, 0, 0 };
typedef struct aNum {
	double data;
	char oper;
	int dataClass;
	int power;
	struct aNum *next;
}num;
typedef struct {
	char *formula;
	int length;
}string;

void setNULL(char *num)//清空一个字符串
{
	int i = 0;
	while (i<5)
	{
		num[i] = NULL;
		++i;
	}
}
int countOperators(string *input, int &counter)//processing step 1
{//计算运算符个数
	int i = 0;
	while (input->formula[i] != '\0')
	{
		switch (input->formula[i++])
		{
		case '+':
		case '-':
		case '*':
		case '/':++counter; break;
		default:break;
		}
		++input->length;
	}
	return 1;
}
int getData(string *input, num *nums)//processing step 2
{//把数字，符号和class存入nums的结构体
	int i = 0;    //counter of input->formula
	int k = 0;  //counter of temp;
	int power = 0;
	char temp[5];
	int inBracket = False;
	num *p = nums;
	num *body;

	while (i <= input->length)
	{
		if ((input->formula[i]<'0' || input->formula[i]>'9')&&input->formula[i]!='.'&&input->formula[i]!='^')
		{//进入此处时数据已经收集完毕
			if (input->formula[i] == '(')
			{
				inBracket = True;
				++i;
				continue;
			}
			if (input->formula[i] == ')')
			{
				inBracket = False;
				++i;
				continue;
			}
			body = (num *)calloc(1, sizeof(num));

			body->data = atof(temp);    //得到数字
			setNULL(temp);              //归零temp
			k = 0;

			switch (input->formula[i])
			{
			case '+':body->dataClass = inBracket == False ? 1 : 3;  //计算当前运算符的等级
				++saved_class[body->dataClass - 1];                 //在等级数组里记录一次
				body->oper = input->formula[i];                     //得到运算符
				break;

			case '-':body->dataClass = inBracket == False ? 1 : 3;
				++saved_class[body->dataClass - 1];
				body->oper = input->formula[i];
				break;

			case 'x':
			case '*':body->dataClass = inBracket == False ? 2 : 4;
				++saved_class[body->dataClass - 1];
				body->oper = input->formula[i];
				break;

			case '/':body->dataClass = inBracket == False ? 2 : 4;
				++saved_class[body->dataClass - 1];
				body->oper = input->formula[i];
				break;

			default:break;
			}
			if (power != 0)
			{
				body->power = power;
				power = 0;
			}
			p->next = body;
			p = p->next;
		}
		else if (input->formula[i] == '^')
		{
			power = input->formula[++i] - 48;
		}
		else
		{
			temp[k++] = input->formula[i];
		}
		++i;
	}
	return 1;
}
double compute(double num1, double num2, char opt)
{//每次运算单独提取
	double result;
	switch (opt)
	{
	case '-':result = num1 - num2; break;
	case '+':result = num1 + num2; break;
	case 'x':
	case '*':result = num1 * num2; break;
	case '/':result = num1 / num2; break;
	}
	return result;
}
int processingData(num *nums)//processing step 3
{//nums作为头结点是没有数据的
	int s = 3;//saved_class
	int i = 0;
	num *p = nums;
	num *p_front;
	while (saved_class[s] == 0&&s>0)
		--s;
	while (p->next->next != NULL)//class oper next 都可以
	{
		if (p->next->dataClass != s + 1)
		{
			p = p->next;
			continue;
		}
		p_front = p;
		p = p->next;//p此时指向待计算的第一个struct aNUm
		if(p->power != 0)
		{
			p->data = pow(p->data, p->power);
			p->power = 0;
		}
		if (p->next->power != 0)
		{
			p->next->data = pow(p->next->data, p->next->power);
			p->next->power = 0;
		}
		p->next->data = compute(p->data, p->next->data, p->oper);

		p_front->next = p->next;
		free(p);
		--saved_class[s];
		while (saved_class[s] == 0&&s!=0)
			--s;
		p = nums;


	}
	if (nums->next->power != 0)//处理单个数字输入的情况，比如2^2
	{
		nums->next->data = pow(nums->next->data, nums->next->power);
	}


	printf("result=%lf\n", nums->next->data);
	return 1;
}
int main()
{
	int counter = 0;
	num *nums = NULL;
	string *input;
	input = (string *)calloc(1, sizeof(string));
	input->formula = (char *)calloc(INIT_STRING_SIZE, sizeof(string));


	puts("Input formula:");
	scanf("%s", input->formula);

	//得到运算符和运算符个数
	countOperators(input, counter);
	//根据运算符个数申请存储数字的空间
	nums = (num *)calloc(1, sizeof(num));
	//存储数字和运算符
	getData(input, nums);
	processingData(nums);

	free(input->formula);
	free(input);
	free(nums->next);
	free(nums);
	system("pause");//如果你是linux或者macos，可能需要去掉这句
	return 0;
}