中缀表达式转后缀表达式

#include <iostream>
#include <vector>
#include <stack>
using namespace std;
char * midToAfterNums(char *s);
int main()
{
char *s = "(((35+15)*(80-70))/20)";
s = midToAfterNums(s);
cout<<s<<endl;
return 0;
}
int getPriority(char ch)//只限于 +-*/(
{
if(ch == '*'||ch == '/')
return 2;
else if(ch == '(')
return 0;
else
return 1;
}
char * midToAfterNums(char *s)
{
vector<char>res;
stack<char>symbol;
for (int i=0; i<strlen(s); i++) {
if ('0'<=s[i]&&s[i]<='9')
res.push_back(s[i]);
else{
if (s[i] == '(')
symbol.push(s[i]);
else if( s[i] == ')')
{
while (true) {
char ch = symbol.top();
symbol.pop();
if(ch == '(')
break;
else
res.push_back(ch);
}
}
else{
if(symbol.empty())
symbol.push(s[i]);
else
{
if(getPriority(s[i])>=getPriority(symbol.top()))
symbol.push(s[i]);
else{
while (!symbol.empty()) {
if(getPriority(s[i])>=getPriority(symbol.top()))
{
symbol.push(s[i]);
break;
}
else{
res.push_back(symbol.top());
symbol.pop();
}
}
if (symbol.empty()) {
symbol.push(s[i]);
}
}
}
}
}
}
while (!symbol.empty()) {
res.push_back(symbol.top());
symbol.pop();
}
char * str = new char[res.size()*2+1];
int j = 0;
for (int i=0; i<res.size(); i++) {
str[j++] = res[i];
str[j++] = ' ';
}
str[j]='\0';
return str;
}