弹出栈
bool Sqstack::pop()///弹出元素
{
if (this->top - this->base)
{
this->top--;
*(this->top) = 0;
this->stacksize--;
return 1;
}
return 0;
}
全部代码：
#include<iostream>
#include<map>
using namespace std;
#define maxsize 1000
typedef int elemtype;
class Sqstack {
public:
void initstack();
bool push(elemtype in);
bool pop();
elemtype gettop();
bool nul();
private:
elemtype* base;//栈底
elemtype* top;//栈顶
int stacksize;//栈容量
};
void Sqstack::initstack()//初始化栈
{
this->base = new elemtype[maxsize];
if (this->base == NULL)
exit(0);
this->top = this->base;
this->stacksize = 0;
}
bool Sqstack::push(elemtype in) ///压入元素
{
if (this->top - this->base < maxsize)
{
*(this->top) = in;
this->top ;
this->stacksize ;
return 1;
}
else
return 0;
}
bool Sqstack::pop()///弹出元素
{
if (this->top - this->base)
{
this->top--;
*(this->top) = 0;
this->stacksize--;
return 1;
}
return 0;
}
elemtype Sqstack::gettop()//取栈顶元素
{
if (this->top - this->base)
return *(this->top - 1);
}
bool Sqstack::nul()
{
if (this->stacksize == 0)
return 1;
return 0;
}
int op(int a1, int a2, char a);
int op(int a1, int a2, char a)
{
if (a == " ")
return a1 a2;
if (a == "-")
return a1 - a2;
if (a == "*")
return a1 * a2;
if (a == "/")
return a1 / a2;
}
void main_func() {
map<char, int> m;
m[" "] = 1;
m["-"] = 1;
m["*"] = 2;
m["/"] = 2;
m["("] = 3;
Sqstack s1, s2;
cout << “输入运算公式： ";
char a[100];
cin >> a;
int a1, a2;
s1.initstack(); s2.initstack();///s1是算符栈 s2为算数栈
for (auto e : a)
{
if (e == " " || e == "
") break;
if (e >= "0" && e <= "9")
{
s2.push(atoi(&e));
}
else if (s1.nul() || m[s1.gettop()] < m[e])
{
s1.push(e);
}
else if (e == ")")
{
while (s1.gettop() != "(")
{
a1 = s2.gettop(); s2.pop();
a2 = s2.gettop(); s2.pop();
s2.push(op(a2, a1, s1.gettop()));
s1.pop();
}
s1.pop();
}
else
{
s1.push(e);
}
}
while (!(s1.nul()))
{
a1 = s2.gettop(); s2.pop();
a2 = s2.gettop(); s2.pop();
s2.push(op(a2, a1, s1.gettop()));
s1.pop();
}
cout << 运算结果： " << endl << s2.gettop() << endl;
}
int main()
{
system("title 单位数字运算器”);
while (true) {
main_func();
}
}
取栈顶元素值
elemtype Sqstack::gettop()//取栈顶元素
{
if (this->top - this->base)
return *(this->top - 1);
}
bool Sqstack::nul()
{
if (this->stacksize == 0)
return 1;
return 0;
}
实现a1、a2运算，a表示运算符
int op(int a1, int a2, char a)
{
if (a == " ")
return a1 a2;
if (a == "-")
return a1 - a2;
if (a == "*")
return a1 * a2;
if (a == "/")
return a1 / a2;
}
压入栈
bool Sqstack::push(elemtype in) ///压入元素
{
if (this->top - this->base < maxsize)
{
*(this->top) = in;
this->top ;
this->stacksize ;
return 1;
}
else
return 0;
}
初始化栈
void Sqstack::initstack()///初始化栈
{
this->base = new elemtype[maxsize];
if (this->base == NULL)
exit(0);
this->top = this->base;
this->stacksize = 0;
}
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