#include <iostream>
#include <string>
#include <stdio.h>
#include <stack>
#include <map>
#include <math.h>
#include <stdlib.h>
#include <sstream>
usingnamespacestd;
charop[8][8];
map<char,int> m;
voidinit()
{
m['+'] = 1, m['-'] = 2, m['*'] = 3, m['/'] = 4, m['('] = 5, m[')'] = 6, m['#'] = 7;
op[1][1] ='>', op[1][2] ='>', op[1][3] ='<', op[1][4] ='<', op[1][5] ='<', op[1][6] ='>', op[1][7] ='>';
op[2][1] ='>', op[2][2] ='>', op[2][3] ='<', op[2][4] ='<', op[2][5] ='<', op[2][6] ='>', op[2][7] ='>';
op[3][1] ='>', op[3][2] ='>', op[3][3] ='>', op[3][4] ='>', op[3][5] ='<', op[3][6] ='>', op[3][7] ='>';
op[4][1] ='>', op[4][2] ='>', op[4][3] ='>', op[4][4] ='>', op[4][5] ='<', op[4][6] ='>', op[4][7] ='>';
op[5][1] ='<', op[5][2] ='<', op[5][3] ='<', op[5][4] ='<', op[5][5] ='<', op[5][6] ='=';
op[6][1] ='>', op[6][2] ='>', op[6][3] ='>', op[6][4] ='>', op[6][6] ='>', op[6][7] ='>';
op[7][1] ='<', op[7][2] ='<', op[7][3] ='<', op[7][4] ='<', op[7][5] ='<', op[7][7] ='=';
}
doubleoperate(doublenum1,charoper,doublenum2)
{
if(oper =='+')
returnnum1 + num2;
if(oper =='-')
returnnum1 - num2;
if(oper =='*')
returnnum1 * num2;
if(oper =='/')
returnnum1 / num2;
}
string trim(string str)
{
index = 0;
if(!str.empty()){
while((index = str.find(' ',index) != string::nops)
str.erase(index,1);
}
returnstr;
}
string change(string str)
{
intstart;
start +="#";
for(inti = 0; i < str.length(); i++){
if(str[i] =='-'){
if(i == 0 || i != 0 && (m[str[i-1]] >= 1 && m[str[i-1]] <= 5
&& str[i+1] >='0'&& str[i+1] <='9'){
str +=" ";
intj = i+1;
start = j;
while(m[str[j]] == 0)
j++;
for(intk = str.length() - 1; k >= j; k--)
str[k] = str[k-3];
str[i] ='(', str[i+1] ='0', str[i+2] ='-';
intl = i+3;
string s = str.substr(start, j - start);
for(intk = 0; k < s.length(); k++)
str[l+k] = s[k];
str[l+s.length()] =')';
}
}
}
str.erase(str.length()-1, 1);
returnstr;
}
booltest(string str)
{
boolifOK =true;
intflag = 0;
stack<char> s;
intstart, e;
str +="#";
for(inti = 0; i < str.length(); i++){
//判断非法字符
if((str[i] <'0'|| str[i] >'9') && m[str[i]] == 0 && str[i] !='.')
returnfalse;
if(str[i] =='#'&& i!= str.length()-1)
returnfalse;
//判断小数点
if(m[str[i]] == 0){
if(flag == 0){
start = i;
flag = 1;
}
}
if(m[str[i]] != 0){
if(flag == 1){
e = i;
string st = str.substr(start, e - start);
intpointNum = 0;
if(st[0] =='.')returnfalse;
for(intj = 0; j < st.length(); j++){
if(st[j] =='.') pointNum++;
}
if(pointNum > 1)returnfalse;
}
flag = 0;
}
//判断运算符
if(str[i] =='+'|| str[i] =='-'|| str[i] =='*'|| str[i] =='/'){
if(i == 0)returnfalse;
if((str[i-1] <'0'|| str[i-1] >'9') && str[i-1] !=')')returnfalse;
if((str[i+1] <'0'|| str[i+1] >'9') && str[i+1] !='(')returnfalse;
}
//判断括号
if(str[i] =='(')
s.push(str[i]);
if(str[i] ==')'){
if(s.empty())returnfalse;
charc = s.top();
if(c =='(')
s.pop();
else
returnfalse;
}
}
//判断括号
if(!s.empty())
ifOK =false;
returnifOK;
}
voidcaculate(string str)
{
str +="#";
intflag = 0;
intstart, e;
stack<double> numStack;//操作数栈
stack<char> operStack;//运算符栈
operStack.push('#');
inti = 0;
while(str[i] !='#'|| operStack.top() !='#'){
if(m[str[i]] == 0){
if(flag == 0){
start = i;
flag = 1;
}
}
else{
if(flag == 1){
e = i;
//string 转 double
stringstream s (str.substr(start, e - start));
doublenum;
s >> num;
numStack.push(num);
flag = 0;
}
charc = operStack.top;
if(op[m[c]][m[str[i]]] =='<'){
operStack.push(str[i]);
i++;
}
elseif(op[m[c]][m[str[i]]] =='='){
operStac.pop();
i++;
}
else{
charoper = operStack.top();
operStac.pop();
doublenum2 = numStack.top();
numStack.pop();
doublenum1 = numStack.top();
numStack.pop();
doubleresult = operate(num1, oper, num2);
numStack.push(result);
}
}
}
printf("\t\t\t= %f\n",numStack.top());
}
intmain()
{
init();//初始化
printf("\n\n\n\t\t\t请输入表达式， 退出请输入end：\n");
string s;
getline(cin, s,"\n");//读取字符串
s = trim(s);//去空格
s = change(s);//处理负号
if(s =="end"){
break;
}
elseif(s.length() > 0){//判断为空
if(!test(s))//检查格式
printf("\t\t\t格式错误\n");
else
caculate(s);//计算
}
else{
printf("\t\t\t输入不能为空\n");
}
}
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