逆波兰式（后缀表达式求值），要支持负数的，感谢大家！
很急，还剩20分钟了；
在线等，一有回答我就看， 只要我测试能通过就采纳。
#include
#include
//#include
using namespace std;
int main(){
string s;
getline(cin,s);
stack<int> sta;
int left=0;
int right=0;
for(int i=0;i<s.size();i++){
if(s[i]>='0'&&s[i]<='9'){
string s2=" ";
while(s[i]>='0'&&s[i]<='9'){
s2+=s[i];
i++;
}
sta.push(atoi(s2.c_str()));
}
else if(s[i]!=' '){
if(!sta.empty()){
right=sta.top();
sta.pop();
}
if(!sta.empty()){
left=sta.top();
sta.pop();
}
switch(s[i]){
case '+':
sta.push(left+right);
break;
case '-':
sta.push(left-right);
break;
case '*':
sta.push(left*right);
break;
case '/':
sta.push(left/right);
break;
default:
break;
}
}
}
cout<<sta.top()<<endl;
return 0;
}
#include
#include
#include
using namespace std;
int main(){
string s;
getline(cin,s);
stack<int> sta;
int left=0;
int right=0;
for(int i=0;i<s.size();i++){
if(s[i]>=‘0’&&s[i]<=‘9’){
string s2=“”;
while(s[i]>=‘0’&&s[i]<=‘9’){
s2+=s[i];
i++;
}
sta.push(stoi(s2));
}
else if(s[i]!=‘ ‘){
if(!sta.empty()){
right=sta.top();
sta.pop();
}
if(!sta.empty()){
left=sta.top();
sta.pop();
}
switch(s[i]){
case ‘+’:
sta.push(left+right);
break;
case ‘-‘:
sta.push(left-right);
break;
case ‘*’:
sta.push(left*right);
break;
case ‘/’:
sta.push(left/right);
break;
default:
break;
}
}
}
cout<<sta.top()<<endl;
return 0;
}
我给个半成品
#include <stdio.h>
#include <stdlib.h>
#define STACK_INIT_SIZE 20
#define STACKINCREMENT 10
typedef char ElemType;
typedef struct
{
ElemType *base;
ElemType *top;
int stackSize;
}sqStack;
void InitStack(sqStack *s)
{
s->base = (ElemType *)malloc(STACK_INIT_SIZE * sizeof(ElemType));
if( !s->base )
exit(0);
s->top = s->base;
s->stackSize = STACK_INIT_SIZE;
}
void Push(sqStack *s, ElemType e)
{
// 栈满，追加空间，鱼油必须懂！
if( s->top - s->base >= s->stackSize )
{
s->base = (ElemType *)realloc(s->base, (s->stackSize + STACKINCREMENT) * sizeof(ElemType));
if( !s->base )
exit(0);
s->top = s->base + s->stackSize;
s->stackSize = s->stackSize + STACKINCREMENT;
}
*(s->top) = e; // 存放数据
s->top++;
}
void Pop(sqStack *s, ElemType *e)
{
if( s->top == s->base )
return;
*e = *--(s->top); // 将栈顶元素弹出并修改栈顶指针
}
int StackLen(sqStack s)
{
return (s.top - s.base);
}
int main()
{
sqStack s;
char c, e;
InitStack( &s );
printf("请输入中缀表达式，以#作为结束标志：");
scanf("%c", &c);
while( c != '#' )
{
while( c>='0' && c<='9' )
{
printf("%c", c);
scanf("%c", &c);
if( c<'0' || c>'9' )
{
printf(" ");
}
}
if( ')' == c )
{
Pop(&s, &e);
while( '(' != e )
{
printf("%c ", e);
Pop(&s, &e);
}
}
else if( '+'==c || '-'==c )
{
if( !StackLen(s) )
{
Push(&s, c);
}
else
{
do
{
Pop(&s, &e);
if( '(' == e )
{
Push(&s, e);
}
else
{
printf("%c ", e);
}
}while( StackLen(s) && '('!=e );
Push(&s, c);
}
}
else if( '*'==c || '/'==c || '('==c )
{
Push(&s, c);
}
else if( '#'== c )
{
break;
}
else
{
printf("\n出错：输入格式错误！\n");
return -1;
}
scanf("%c", &c);
}
while( StackLen(s) )
{
Pop(&s, &e);
printf("%c ", e);
}
return 0;
}
你好