我要评论逆波兰计算器
所谓的逆波兰计算器，就是将我们常见的中缀表达式，转换为后缀表达式，来供计算机运算的计算器。
适合栈刚入门做练习
#include <iostream>
#include <cstdlib>
#include <cctype>
using namespace std;
const int MaxSize = 30;
const int Stack_Init_Size = 30;
const int StackIncrement = 10;
typedef char ElemType_c;
typedef double ElemType_d;
typedef struct{
ElemType_c *top;
ElemType_c *base;
int StackSize;
}sqStack_c;
typedef struct{
ElemType_d *top;
ElemType_d *base;
int StackSize;
}sqStack_d;
bool InitStack_c(sqStack_c *s);
bool InitStack_d(sqStack_d *s);
void Push_c(sqStack_c *s,ElemType_c e);
void Push_d(sqStack_d *s,ElemType_d e);
void Pop_c(sqStack_c *s,ElemType_c *e);
void Pop_d(sqStack_d *s,ElemType_d *e);
int LenStack_c(sqStack_c s);
int LenStack_d(sqStack_d s);
int main()
{
sqStack_c s;
InitStack_c(&s);
ElemType_c c,e;
ElemType_c arr[MaxSize];
int i = 0;
cout << "Please enter the infix expression(# to stop): ";
cin >> c;
while('#' != c){
while(isdigit(c) || '.' == c){
arr[i++] = c;
arr[i] = '\0';
cin >> c;
if(!(isdigit(c) || '.' == c))
{
arr[i++] = ' ';
arr[i] ='\0';
}
}
if(')' == c)
{
Pop_c(&s,&e);
while('(' != e){
arr[i++] = e;
arr[i++] = ' ';
arr[i] = '\0';
Pop_c(&s,&e);
}
}
else if('+' == c || '-' == c)
{
if(!LenStack_c(s))
Push_c(&s,c);
else
{
do{
Pop_c(&s,&e);
if('(' == e)
Push_c(&s,e);
else
{
arr[i++] = e;
arr[i++] = ' ';
arr[i] = '\0';
}
}while('(' != e && LenStack_c(s));
Push_c(&s,c);
}
}
else if('*' == c || '/' == c || '(' == c)
{
Push_c(&s,c);
}
else if('#' == c)
{
break;
}
else
{
cerr << "Enter Error.\n";
break;
}
cin >> c;
}
while(LenStack_c(s)){
Pop_c(&s,&e);
arr[i++] = e;
arr[i++] = ' ';
arr[i] = '\0';
}
arr[i-1] = '#';
// calc
sqStack_d calc;
InitStack_d(&calc);
ElemType_d d,f;
int j = 0, k = 0;
char str[MaxSize];
char oop = arr[j++];
while('#' != oop){
while(isdigit(oop) || '.' == oop){
str[k++] = oop;
str[k] = '\0';
if(k >= MaxSize)
{
cerr << "Runout.\n";
return -1;
}
oop = arr[j++];
if(' ' == oop)
{
d = atof(str);
Push_d(&calc,d);
k = 0;
break;
}
}
switch(oop){
case '+': Pop_d(&calc,&d);
Pop_d(&calc,&f);
Push_d(&calc,f+d); break;
case '-': Pop_d(&calc,&d);
Pop_d(&calc,&f);
Push_d(&calc,f-d); break;
case '*': Pop_d(&calc,&d);
Pop_d(&calc,&f);
Push_d(&calc,f*d); break;
case '/': Pop_d(&calc,&d);
Pop_d(&calc,&f);
Push_d(&calc,f/d); break;
}
oop = arr[j++];
}
Pop_d(&calc,&d);
cout.setf(ios_base::fixed);
cout.setf(ios::showpoint);
cout.precision(4);
cout << "The final result is: " << d;
return 0;
}
bool InitStack_c(sqStack_c *s)
{
s->base = (ElemType_c *)malloc(Stack_Init_Size * sizeof(ElemType_c));
if(!s->base)
return false;
s->top = s->base;
s->StackSize = Stack_Init_Size;
return true;
}
bool InitStack_d(sqStack_d *s)
{
s->base = (ElemType_d *)malloc(Stack_Init_Size * sizeof(ElemType_d));
if(!s->base)
return false;
s->top = s->base;
s->StackSize = Stack_Init_Size;
return true;
}
void Push_c(sqStack_c *s,ElemType_c e)
{
if(s->top - s->base >= s->StackSize)
{
s->base = (ElemType_c *)realloc(s->base,(s->StackSize + StackIncrement) * sizeof(ElemType_c));
if(!s->base)
exit(EXIT_FAILURE);
s->top = s->base + s->StackSize;
s->StackSize = s->StackSize +StackIncrement;
}
*(s->top) = e;
s->top++;
}
void Push_d(sqStack_d *s,ElemType_d e)
{
if(s->top - s->base >= s->StackSize)
{
s->base = (ElemType_d *)realloc(s->base,(s->StackSize + StackIncrement) * sizeof(ElemType_d));
if(!s->base)
exit(EXIT_FAILURE);
s->top = s->base + s->StackSize;
s->StackSize = s->StackSize + StackIncrement;
}
*(s->top) = e;
s->top++;
}
void Pop_c(sqStack_c *s,ElemType_c *e)
{
if(s->top == s->base)
return;
*e = *--(s->top);
}
void Pop_d(sqStack_d *s,ElemType_d *e)
{
if(s->top == s->base)
return;
*e = *--(s->top);
}
int LenStack_c(sqStack_c s)
{
if(s.top == s.base)
return 0;
return s.top - s.base;
}
int LenStack_d(sqStack_d s)
{
if(s.top == s.base)
return 0;
return s.top - s.base;
}
本文地址：https://blog.csdn.net/weixin_45677702/article/details/108155696
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