@huange7
C语言实现四则运算
用C语言实现四则运算（QG第二次训练营作业）
头文件
代码：
#include <stdio.h>
#include<malloc.h>
#include<math.h>
typedef enum Status {
ERROR = 0, SUCCESS = 1
} Status;
typedef struct StackNode
{
char cData;
double data;
struct StackNode *next;
}StackNode, *LinkStackPtr;
typedef struct LinkStack{
LinkStackPtr top;
int count;
}LinkStack;
Status initLStack(LinkStack *s);//初始化栈
Status isEmptyLStack(LinkStack *s);//判断栈是否为空
double getTopLStackint(LinkStack *s);//得到栈顶元素
char getTopLStackchar(LinkStack *s);//得到栈顶元素
Status destroyLStack(LinkStack *s);//销毁栈
Status pushLStackdouble(LinkStack *s,double data);//入栈
Status pushLStackchar(LinkStack *s,char data);//入栈
Status popLStackdouble(LinkStack *s,double *data);//出栈
Status popLStackchar(LinkStack *s,char *data);//出栈
void inputCheck(int *val); //检查输入
void inputString(char s[]); //字符串的输入
Status checkString(char s[]); //检查字符串的正确
Status convertString(char s1[],char s2[],LinkStack *s); //将中缀表达式转化为后缀表达式
int judgePriority(char a, char b);
double computeString(LinkStack *s1,char s[]);
函数实现
#include "calculatior.h"
Status initLStack(LinkStack *s) //初始化
{
s->count = 0;
s->top = (LinkStackPtr)malloc(sizeof(StackNode));
if(s->top == NULL)
{
printf("\t\t\t\t动态分配内存失败!\n");
return ERROR;
}
else
{
s->top = NULL;
}
return SUCCESS;
}
Status isEmptyLStack(LinkStack *s) //判断链栈是否为空
{
if(s->count == 0)
{
return SUCCESS;
}
return ERROR;
}
Status destroyLStack(LinkStack *s) //销毁栈
{
if(isEmptyLStack(s))
return ERROR;
while(s->top != NULL)
{
LinkStackPtr p = s->top;
s->top = s->top->next;
free(p);
}
s->count = 0;
return SUCCESS;
}
Status pushLStackdouble(LinkStack *s,double data) //入栈
{
LinkStackPtr p = (LinkStackPtr)malloc(sizeof(StackNode));
if(p == NULL)
{
printf("\t\t\t\t动态分配内存失败!\n");
return ERROR;
}
p->data = data;
p->next = s->top;
s->top = p;
s->count ++;
return SUCCESS;
}
Status pushLStackchar(LinkStack *s,char data) //入栈
{
LinkStackPtr p = (LinkStackPtr)malloc(sizeof(StackNode));
if(p == NULL)
{
printf("\t\t\t\t动态分配内存失败!\n");
return ERROR;
}
p->cData = data;
p->next = s->top;
s->top = p;
s->count ++;
return SUCCESS;
}
Status popLStackdouble(LinkStack *s,double *data) //出栈
{
if(isEmptyLStack(s))
return ERROR;
*data = s->top->data;
LinkStackPtr p = s->top;
s->top = p->next;
free(p);
p = NULL;
s->count--;
return SUCCESS;
}
Status popLStackchar(LinkStack *s,char *data) //出栈
{
if(isEmptyLStack(s))
return ERROR;
*data = s->top->cData;
LinkStackPtr p = s->top;
s->top = p->next;
free(p);
p = NULL;
s->count--;
return SUCCESS;
}
void inputString(char s[])
{
int i=0;
printf("请输入表达式:");
scanf("%s", s);
getchar();
while(1)
{
if((s[i] < '0'||s[i] > '9')&&(s[i] != '+'&&s[i] != '-'&&s[i] != '*'&&s[i] != '/'&&s[i] != '.'&&s[i]!= '('&&s[i] != ')'))
{
printf("请输入正确的表达式！");
scanf("%s", s);
i = 0;
}else
{
i++;
}
if(s[i] == '\0')
break;
}
checkString(s);
}
Status checkString(char s[]) //检查字符串的输入
{
int i,j = 0;
char a[20] = {0}; //存放运算符
int flag = 0; // 用于判断该数是否为负数 例如：5*-3，则3的实际为-3
int bracket = 0; // 检测括号的配对关系
for(i = 0; s[i] != '\0'; i++)
{
//将数字间的运算符存储起来
if(s[i] == '+'||s[i] == '-'||s[i] == '*'||s[i] == '/')
{
a[j++] = s[i];
}
//判断括号是否匹配
if(s[i] == '(')
bracket = 1;
if(s[i] == ')'&&bracket == 1)
bracket = 0;
//将数字间的字符进行运算并判断是否正确
if((s[i+1] >= '0'&&s[i+1] <= '9')||s[i+1] == '(')
{
char c = a[0];
for(int k = 1;k < j; k++)
{
if((c =='+'&& a[k]=='-')||(c == '-'&&a[k] == '+'))
c = '-';
else if(c == '-'&& a[k] == '-')
{
c = '+';
}
else if(c =='*' &&a[k] == '+')
{
c = '*';
}
else if((c == '*'||c == '/')&& a[k] == '-')
{
if(flag == 0)
flag = 1;
else
flag = 0;
}
else if((c == '+'||c == '-')&&(a[k] == '*'||a[k] == '/'))
{
printf("输入表达式错误！请重新输入：");
inputString(s);
}
}
if(c == '+'||c == '-'|| c == '*'|| c == '/')
{
s[i-j+1] = c;
for(int k = i-j+2;s[k] != '\0'; k++)
s[k] = s[k+j-1];
i = i-j+2;
}
for(int k = 0; k < j; k++)
a[k] = '\0';
j = 0;
}
}
if(s[i-1] == '+'||s[i-1] == '-'||s[i-1] == '*'||s[i-1] == '/'||bracket != 0)
{
printf("表达式输入错误!请重新输入：");
inputString(s);
}
printf("\n最终的表达式为:");
for(int k = 0; s[k] != '\0'; k++)
printf("%c" ,s[k]);
printf("\n");
printf("bra = %d\n", bracket);
return SUCCESS;
}
double getTopLStackdouble(LinkStack *s) //得到栈顶元素
{
if(isEmptyLStack(s))
return 0;
return (s->top->data);
}
char getTopLStackchar(LinkStack *s) //得到栈顶元素
{
if(isEmptyLStack(s))
return '\0';
return (s->top->cData);
}
Status convertString(char s1[],char s2[],LinkStack *s)//将中缀表达式转化为后缀表达式
{
int i = 0 , j = 0;
int flag = 0; //用于分隔右括号和运算符
char c;
while(s1[i] != '\0')
{
if((s1[i] >= '0'&&s1[i] <= '9')||s1[i] == '.')
{
s2[j++] = s1[i];
if(s1[i] >= '0'&&s1[i] <= '9')
printf("是数字，直接赋值：%.2lf\n",(double)(s1[i]-48));
else
printf("是小数点，直接赋值！\n");
}
if(s1[i+1] == ')')
{
if(s1[i+2] == '+'||s1[i+2] == '-'||s1[i+2] == '*'||s1[i+2] == '/'||s1[i+2] == '\0'||s1[i+2] == ')')
{
if(flag == 0)
{
flag = 1;
s2[j++] = ',';
printf("数字转化完毕！加个逗号\n");
}
}
}
if(s1[i+1] == '+'||s1[i+1] == '-'||s1[i+1] == '*'||s1[i+1] == '/'||s1[i+1] == '\0')
{
if(flag == 1)
{
flag = 0;
}
else
{
s2[j++] = ',';
printf("数字转化完毕，加个逗号!\n");
}
}
if(s1[i] == '+'||s1[i] == '-'||s1[i] == '*'||s1[i] == '/')
{
if(isEmptyLStack(s))
{
pushLStackchar(s, s1[i]);
printf("空栈或者遇到左括号，直接放入\n");
}
else
{
switch(judgePriority(s1[i], getTopLStackchar(s)))
{
case -1:
{
pushLStackchar(s , s1[i]);
printf("运算符优先级比栈顶高，入栈！\n");
break;
}
case 0:
case 1:
{
while(judgePriority(s1[i], getTopLStackchar(s)) != -1)
{
popLStackchar(s , &s2[j++]);
printf("运算符优先级比栈顶低或者相等，出栈！\n");
if(isEmptyLStack(s))
{
printf("空栈！暂停比较！\n");
break;
}
}
if(!isEmptyLStack(s)&&(judgePriority(s1[i], getTopLStackchar(s)) == -1))
{
printf("栈不空！并且运算符优先级比栈顶高！直接入栈！\n");
pushLStackchar(s, s1[i]);
}
if(isEmptyLStack(s))
{
printf("空栈！直接压栈！\n");
pushLStackchar(s , s1[i]);
}
break;
}
}
}
}
if(s1[i] == '(')
{
pushLStackchar(s, s1[i]);
printf("遇到左括号，压栈！\n");
}
if(s1[i] == ')')
{
printf("遇到右括号！开始出栈！\n");
while(1)
{
popLStackchar(s, &s2[j++]);
if(s->top == NULL||s->top->cData == '(')
break;
}
popLStackchar(s, &c);
printf("出栈完毕！栈顶元素为:%c\n", getTopLStackchar(s));
}
i++;
}
while(!isEmptyLStack(s))
{
printf("s1扫描完毕，将栈中元素全部给s2\n");
popLStackchar(s, &s2[j++]);
}
printf("转换完成的后缀表达式为:");
for(i = 0;s2[i] != '\0'; i++)
printf("%c", s2[i]);
printf("\n");
return SUCCESS;
}
int judgePriority(char a, char b) //判断符号优先级
{
if((( a == '+'|| a == '-')&&( b == '+'|| b == '-'))||((a == '*'||a == '/')&&(b == '*'||b == '/')))
return 1; //代表二者优先级相等
else if((a == '+'||a == '-')&&(b == '*'||b == '/'))
return 0; //代表右边优先级高
else
return -1; //代表左边优先级高
}
double computeString(LinkStack *s1,char s[])
{
double temp = 0;
int flag = 0;
for(int i = 0;s[i] != '\0'; i++)
{
if(s[i] == '.')
flag = 1;
if(s[i] >= '0'&&s[i] <= '9')
{
if(flag != 0)
{
temp += (double)(s[i]-48)*pow(10,-flag);
flag ++;
}
else
temp = temp*10 + (double)(s[i]-48);
}
if(s[i] == ',')
{
pushLStackdouble(s1, temp);
temp = 0;
flag = 0;
}
if(s[i] == '+'||s[i] == '-'||s[i] == '*'||s[i] == '/')
{
double a,b,temp2;
popLStackdouble(s1, &a);
popLStackdouble(s1, &b);
switch(s[i])
{
case '+':temp2 = a + b;pushLStackdouble(s1, temp2);temp2 = 0;break;
case '-':temp2 = b - a;pushLStackdouble(s1, temp2);temp2 = 0;break;
case '*':temp2 = b * a;pushLStackdouble(s1, temp2);temp2 = 0;break;
case '/':temp2 = b / a;pushLStackdouble(s1, temp2);temp2 = 0;break;
}
}
}
popLStackdouble(s1, &temp);
return temp;
}
主函数
#include "calculatior.h"
int main()
{
char aExpression1[100] = {0};
char aExpression2[100] = {0};
LinkStack *symbol = (LinkStack *)malloc(sizeof(LinkStack));
LinkStack *number = (LinkStack *)malloc(sizeof(LinkStack));
initLStack(symbol);
initLStack(number);
inputString(aExpression1);
convertString(aExpression1,aExpression2,symbol);
double temp = computeString(number,aExpression2);
printf("\n 结果为-->%.2lf\n", temp);
destroyLStack(symbol);
destroyLStack(number);
free(symbol);
free(number);
system("pause");
return 0;
}