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1、簡介
計算器是我們生活中很常見的東西，它可以由多種語言多種方式來實現，今天我想講的是基于C++語言，由QT實現的可以計算大數的簡單計算器。
2、作品演示
（1）簡單四則運算
（2）大數運算
3、重點原理講解
（1）四則運算如何實現 （2）大數的加減乘除
4、代碼主體框架
1個主函數； 兩個類： 一個calculator類，實現了對界面的布局，其實這個布局很簡單，就設置了一些按鈕以及一個顯示框。
類的聲明：
class calculator : public QMainWindow
{
Q_OBJECT
public:
calculator(QWidget *parent = 0);
~calculator();
private:
QLineEdit *inputLine;//顯示框
QString input="0"; //輸入框
//0-9按鈕
QPushButton *zeroButton;
QPushButton *oneButton;
QPushButton *twoButton;
QPushButton *threeButton;
QPushButton *fourButton;
QPushButton *fiveButton;
QPushButton *sixButton;
QPushButton *sevenButton;
QPushButton *eightButton;
QPushButton *nineButton;
QPushButton *addButton;
QPushButton *subButton;
QPushButton *divButton;
QPushButton *mulButton;
QPushButton *equButton;
QPushButton *timButton; //Time
QPushButton *decButton;
QPushButton *botButton;
QPushButton *CEButton;
QPushButton *ACButton;
QPushButton *lefButton;
QPushButton *rigButton;
private slots:
void buttonZeroClicked();
void buttonOneClicked();
void buttonTwoClicked();
void buttonThreeClicked();
void buttonFourClicked();
void buttonFiveClicked();
void buttonSixClicked();
void buttonSevenClicked();
void buttonEightClicked();
void buttonNineClicked();
void buttonAddClicked();//+
void buttonSubClicked();//-
void buttonMulClicked();//乘
void buttonDivClicked();//除
void buttonTimClicked(); //時間
void buttonDecClicked();//小數點
void buttonBotClicked(); //加減號
void buttonEquClicked();//等于號
void buttonLefClicked();//左括號
void buttonRigClicked();//右括號
void buttonCEClicked();//CE
void buttonACClicked();//AC
};界面布局：
calculator::calculator(QWidget *parent) : QMainWindow(parent)
{
QWidget *widget=new QWidget; //構建一個QWidget布局將設置的布局添加進這個QWidget
this->setCentralWidget(widget);
inputLine=new QLineEdit;
inputLine->setText(input);
zeroButton=new QPushButton("0");
oneButton=new QPushButton("1");
twoButton=new QPushButton("2");
threeButton=new QPushButton("3");
fourButton=new QPushButton("4");
fiveButton=new QPushButton("5");
sixButton=new QPushButton("6");
sevenButton=new QPushButton("7");
eightButton=new QPushButton("8");
nineButton=new QPushButton("9");
decButton=new QPushButton(".");
botButton=new QPushButton("±");
timButton=new QPushButton("Time");
addButton=new QPushButton("+");
subButton=new QPushButton("-");
mulButton=new QPushButton("*");
divButton=new QPushButton("/");
equButton=new QPushButton("=");
lefButton=new QPushButton("(");
rigButton=new QPushButton(")");
CEButton=new QPushButton("CE");
ACButton=new QPushButton("AC");
QGridLayout *H=new QGridLayout(this); //聲明了一個網格布局
inputLine->setFixedHeight(50); //調整第一行大小
CEButton->setFixedHeight(50);
ACButton->setFixedHeight(50);
H->addWidget(inputLine,0,0,1,3);
H->setRowStretch(0,100);
H->addWidget(CEButton,0,3);
H->addWidget(ACButton,0,4);
H->addWidget(oneButton,1,0);
H->addWidget(twoButton,1,1);
H->addWidget(threeButton,1,2);
H->addWidget(botButton,1,3);
H->addWidget(timButton,1,4);
H->addWidget(fourButton,2,0);
H->addWidget(fiveButton,2,1);
H->addWidget(sixButton,2,2);
H->addWidget(addButton,2,3);
H->addWidget(subButton,2,4);
H->addWidget(sevenButton,3,0);
H->addWidget(eightButton,3,1);
H->addWidget(nineButton,3,2);
H->addWidget(mulButton,3,3);
H->addWidget(divButton,3,4);
H->addWidget(zeroButton,4,0);
H->addWidget(decButton,4,1);
H->addWidget(lefButton,4,2);
H->addWidget(rigButton,4,3);
H->addWidget(equButton,4,4);
widget->setLayout(H); //將布局顯示出來
connect(zeroButton,SIGNAL(clicked()),this,SLOT(buttonZeroClicked()));//信號與槽函數
connect(oneButton,SIGNAL(clicked()),this,SLOT(buttonOneClicked()));
connect(twoButton,SIGNAL(clicked()),this,SLOT(buttonTwoClicked()));
connect(threeButton,SIGNAL(clicked()),this,SLOT(buttonThreeClicked()));
connect(fourButton,SIGNAL(clicked()),this,SLOT(buttonFourClicked()));
connect(fiveButton,SIGNAL(clicked()),this,SLOT(buttonFiveClicked()));
connect(sixButton,SIGNAL(clicked()),this,SLOT(buttonSixClicked()));
connect(sevenButton,SIGNAL(clicked()),this,SLOT(buttonSevenClicked()));
connect(eightButton,SIGNAL(clicked()),this,SLOT(buttonEightClicked()));
connect(nineButton,SIGNAL(clicked()),this,SLOT(buttonNineClicked()));
connect(addButton,SIGNAL(clicked()),this,SLOT(buttonAddClicked()));
connect(subButton,SIGNAL(clicked()),this,SLOT(buttonSubClicked()));
connect(mulButton,SIGNAL(clicked()),this,SLOT(buttonMulClicked()));
connect(divButton,SIGNAL(clicked()),this,SLOT(buttonDivClicked()));
connect(botButton,SIGNAL(clicked(bool)),this,SLOT(buttonBotClicked()));//正負號
connect(timButton,SIGNAL(clicked(bool)),this,SLOT(buttonTimClicked()));//時間
connect(decButton,SIGNAL(clicked(bool)),this,SLOT(buttonDecClicked()));//點號
connect(lefButton,SIGNAL(clicked(bool)),this,SLOT(buttonLefClicked()));//左括號
connect(rigButton,SIGNAL(clicked(bool)),this,SLOT(buttonRigClicked()));//右括號
connect(CEButton,SIGNAL(clicked()),this,SLOT(buttonCEClicked()));
connect(ACButton,SIGNAL(clicked()),this,SLOT(buttonACClicked()));
connect(equButton,SIGNAL(clicked()),this,SLOT(buttonEquClicked())); //等于號*/
}槽函數實現部分舉例說明，其它類似：
void calculator::buttonZeroClicked() //以下是實現相應的槽函數
{
if(input=="0")
input='0';
else input=input+'0';
inputLine->setText(input);
}
void calculator::buttonTimClicked() //Time
{
input=QDateTime::currentDateTime().toString("yyyy-MM-dd hh:mm:ss:zzz"); //格式化輸出當前時間
inputLine->setText(input);
}
點擊等于號的時候調用Change函數和Exchange函數，對式子進行運算。
Change 函數，將顯示框里面的中綴表達式轉化為了后綴表達式，存入OPS字符數組中，數字之間用#分開，保存數組長度，方便后面的運算。
Exchange函數，將后綴表達式進行運算，對每兩個數的加法減法乘法或者除法都是采用大數運算，通過CDashu類對 + – * / 的重載，然后在Exchange 函數中建立對象調用，最后將返回值再轉化為字符輸出到屏幕上。
void calculator::buttonEquClicked()//等于號
{
std::string str=input.toStdString();
const char *S=str.c_str();
cout<<S[strlen(S)];
char OPS[max1];
int len;
double result;
char* change = new char[max1];
bool flag;
Change(S,OPS,len);
change = EXchange(OPS,len,result,flag);
//QString::number(result,10,6);
input=input+"="+change;
inputLine->setText(input);
}
int Change(const char *S,char OPS[],int &len)
{
QStack<char> OPE;
int i = 0 ,j = 0;
int l = strlen(S);
for( i ;i < strlen(S);i++)
{
switch(S[i])
{
case '+':
if(OPE.isEmpty())
OPE.push(S[i]);
else if(OPE.top() == '*' || OPE.top() == '/' || OPE.top() == '-')
{
OPS[j++] = OPE.pop();
i--;//多次判斷OPE.top()符號的優先級是否高于'+'
}
else
OPE.push(S[i]);
break;
case '-':
//if('('!=S[i-1]&&0!=i)
//{
if(OPE.isEmpty())
OPE.push(S[i]);
else if(OPE.top() == '*' || OPE.top() == '/' || OPE.top() == '+')
{
OPS[j++] = OPE.pop();
i--;
}
else
OPE.push(S[i]);
break;
//}
/*else
{
while ((S[i] >= '0'&&S[i] <= '9' )|| S[i] == '.'||('-'==S[i]&&(S[i-1]<'0'||S[i-1]>'9' || i == 0)))
{
if(S[i] == '-')
OPS[j++]='#';
OPS[j++] = S[i];
i++;
}
i--;
OPS[j++] = '#'; //數字中的間隔符
}*/
case '*':
if(OPE.isEmpty())
{
OPE.push(S[i]);
}
else if(OPE.top() == '/')
{
OPS[j++] = OPE.pop();
i--;
}
else
OPE.push(S[i]);
break;
case '/':
if(OPE.isEmpty())
{
OPE.push(S[i]);
}
else if(OPE.top() == '*')
{
OPS[j++] = OPE.pop();
i--;
}
else
OPE.push(S[i]);
break;
case'(':
OPE.push(S[i]);
break;
case')':
while (OPE.top() != '(')
{
OPS[j++] = OPE.pop();//遇到右括號，一直彈出操作符知道遇到左括號
}
OPE.pop();//直接不放入數組彈出左括號
break;
default:
while (S[i] >= '0'&&S[i] <= '9' || S[i] == '.'||('-'==S[i]&&S[i-1]<'0'&&S[i-1]>'9'))
{
OPS[j++] = S[i];
i++;
}
i--;
OPS[j++] = '#'; //數字中的間隔符
break;
}//switch
}//for
while (!OPE.isEmpty())
{
OPS[j++] = OPE.pop();
}
len = j;
return 0;
}//Change
char* EXchange(char OPS[], int len, double &result,bool &flag)
{
int tag = 0,t3;
QStack<char*> SZ;
char *s = new char[max1];
char *str1 = new char[max1];
char *str2 = new char[max1];
char *str = new char[max1];
char st1[max1][max1];
CDashu x1;
CDashu x2;
CDashu y;
int i,j,t = 0,temp;
for(i = 0;i < len;i++)
{
switch(OPS[i])
{
case '+':
str1 = SZ.pop();
str2 = SZ.pop();
x1.Change(str1);
x2.Change(str2);
y = x2 + x1;
tag = 0;
temp = 0;
if(y.a[0])
{
s[tag] = y.a[0]+'0';
tag++;
}
else
temp++;
for( ;tag <= y.getlength()-temp;tag++)
{
s[tag] = y.a[tag + temp]+'0';
}
s[tag] = '\0';
SZ.push(s);
break;
case '-':
str1 = SZ.pop();
str2 = SZ.pop();
x1.Change(str1);
x2.Change(str2);
y = x2 - x1;
tag = 0;
temp = 0;
if(y.getflag())
{
s[tag] = '-';
tag++;
}
if(y.a[0])
{
s[tag] = y.a[0]+'0';
tag++;
}
else
temp++;
if(s[0] == '-')
{
for( ;tag <= y.getlength();tag++)
{
s[tag] = y.a[tag]+'0';
}
s[tag] = '\0';
}
else
{
for( ;tag <= y.getlength()-temp;tag++)
{
s[tag] = y.a[tag + temp]+'0';
}
s[tag] = '\0';
}
SZ.push(s);
break;
case '*':
int max,min,max2;
str1 = SZ.pop();
str2 = SZ.pop();
x1.Change(str1);
x2.Change(str2);
y = x1*x2;
y.get(max,max2,min);
j = 0;
for(t3 = max;t3 >= min;t3--)
{
s[j++] = y.a[t3]+'0';
}
s[j] = '\0';
SZ.push(s);
break;
case '/':
{
str1 = SZ.pop();
str2 = SZ.pop();
x1.Change(str1);
x2.Change(str2);
y = x2 / x1;
int x = 0;
i = 0;
int num[max1];
while(y.yushu[0])
{
num[x] = y.yushu[0]%10;
y.yushu[0] = y.yushu[0]/10;
x++;
}
x--;
while(x > -1)
{
s[i] = num[x]+'0';
x--;
i++;
}
s[i] = '.';
for(i = i+1,j = 1;j < 50;i++,j++)
{
s[i] = y.yushu[j]+'0';
}
s[i] = '\0';
SZ.push(s);
}
break;
default:
j = 0;
while (OPS[i] != '#')
{
st1[t][j] = OPS[i];
j++;
i++;
}
st1[t][j] = '\0';
SZ.push(st1[t]);
t++;
break;
}
}
return SZ.top();
}下面重點介紹一下大數類：
類的聲明與部分成員函數的實現
#ifndef CDASHU_H
#define CDASHU_H
#include<cstring>
using namespace std;
#define max1 500
#define MAXN 9999
class CDashu
{
public:
int a[max1];
int yushu[max1];
CDashu() { length = 1; memset(a, 0, sizeof(a)); } //構造函數
void Change( char *s); //將字符串轉換為大數
long getlength()
{
return length;
}
int getflag()
{
return flag;
}
friend int Compare(CDashu a,CDashu b);
void get(int &m,int &m2,int &min)
{
m = max;
m2 = max2;
min = this->min;
}
~CDashu();
CDashu operator +(CDashu b);//對各類運算的重載
CDashu operator -(CDashu b);
CDashu operator *(CDashu b);
CDashu operator /(CDashu b);
private:
long length;
int flag;
int max,min,max2;
};
#endif // CDASHU_H大數類的實現：
#include "cdashu.h"
#include "cdashu.h"
#include <iostream>
#include <string.h>
using namespace std;
/*
ostream& operator<<(ostream& out, CDashu& b) //重載輸出運算符
{
int i;
out << b.a[b.length - 1];
for (i = b.length - 2; i >= 0; i--)
{
out.width(4);
out.fill('0');
out << b.a[i];
}
return out;
}*/
void CDashu::Change( char *s)
{
memset(a, 0, sizeof(a));
long l = strlen(s);
length = l;
for (int i = 1; i <= l; i++)
{
a[i] = (int)s[i-1] - '0';
}
for (int i = 1; i <= l; i++)
{
cout << a[i];
}
cout << endl;
}
CDashu CDashu::operator+(CDashu b)
{
int i = length, j = b.length;
if (i >= j)
{
for (; i > 0 && j > 0; i--, j--)
a[i] += b.a[j];//逐個相加
i = length;
for (i; i >= 0; i--)
{
if (a[i] >= 10) //進位運算
{
a[i - 1] += a[i] / 10;
a[i] %= 10;
}
}
return *this;
}
else
{
for (; i >= 0 && j >= 0; i--, j--)
b.a[j] += a[i];//逐個相加
i = b.length;
for (i; i > 0; i--)
{
if (b.a[i] >= 10) //進位運算
{
b.a[i - 1] += b.a[i] / 10;
b.a[i] %= 10;
}
}
return b;
}
}
CDashu CDashu::operator -(CDashu b)
{
flag = 0;
b.flag = 0;
int i, j;
if (length == b.length)
{
i = 1;j = 1;
while (a[i] == b.a[i])
{
i++;
}
if (a[i] < b.a[i])
b.flag = 1;
}
i = length;
j = b.length;
if (i < j || b.flag)
{
for (i; i > 0 && j > 0; i--, j--)
b.a[j] -= a[i];//一一相減
i = b.length;
for (i; i > 0; i--)
{
if (b.a[i] < 0) //補位運算
{
b.a[i] += 10;
b.a[i - 1] -= 1;
}
}
return b;
}
else
{
for (i; i >= 0 && j >= 0; i--, j--)
a[i] -= b.a[j];//一一相減
i = length;
for (i; i >= 0; i--)
{
if (a[i] < 0) //補位運算
{
a[i] += 10;
a[i - 1] -= 1;
}
}
return *this;
}
cout << endl;
}
CDashu CDashu::operator *(CDashu b)
{
CDashu t;
int i, j;
t.max = t.min = t.max2 = 1;
for (i = length; i > 0; i--)
{
for (j = b.length; j > 0; j--)
{
t.a[length+b.length+1 -(i + j)] += a[i] * b.a[j];//t.a[]初始化為0
t.min = min<(length+b.length+1 -(i + j))?t.min:(length+b.length+1 -(i + j));
t.max = max>(length+b.length+1 -(i + j))?t.max:(length+b.length+1 -(i + j));
}
}
for (i = t.min; i <= t.max; i++)
{
if (t.a[i] >= 10)
{
t.a[i + 1] += t.a[i] / 10;
t.a[i] = t.a[i] % 10;
t.max2 = i+1;
}
}
t.max = t.max > t.max2 ? t.max:t.max2;
return t;
}
CDashu CDashu::operator /(CDashu b)
{
int i,j,flag = 1,count = 0,tag = 0,mm=0;
min = 1;
flag = Compare(*this,b);
max = length;
if (length < b.length || flag == 0)
count = 0;
else
{
while (flag == 1 || flag == 2)
{
if(min == length && a[min] == 0)
{
break;
}
else
{
i = length;
j = b.length;
count++;
for ( ; i >= min && j > 0; i--, j--)
a[i] -= b.a[j];//一一相減
i = length;
for (i; i >= min; i--)
{
if (a[i] < 0) //補位運算
{
a[i] += 10;
a[i - 1] -= 1;
}
}
i = min;
if (a[i] == 0 && i != length)
{
while (a[i] == 0)
{
i++;
}
min = i;
}//如果有減到前面為0,最小下標右移到不為0的位置
flag = Compare(*this,b);//比較兩個數的大小
}
cout<<count<<endl;
}//while
}//else
cout << count << '.';
yushu[0] = count;
tag = 0;
for(i = 1;i <= length;i++)
{
if(a[i] != 0)
{
tag = 1;
break;
}
}
if(!tag)
{
for(i = 1;i < 50;i++)
{
yushu[i] = 0;
}
}
else
{
int jingdu = 1;
while(jingdu < 50)
{
count = 0;
/*if(min == length && a[min] == 0)
{
for( ;jingdu < 30;jingdu++)
{
yushu[jingdu] = 0;
}
break;
}*/
length++;
a[length] = 0;
flag = Compare(*this,b);//比較兩個數的大小
if(flag == 2)
{
yushu[jingdu] = 1;
jingdu++;
for( ; jingdu < 50;jingdu++)
{
yushu[jingdu] = 0;
}
}
else
{
if (flag == 0)
{
yushu[jingdu] = 0;
jingdu++;
}
else
{
while (flag == 1 || flag==2)
{
if(min == length && a[min] == 0)
{
mm = 1;
yushu[jingdu] = count;
for( jingdu = jingdu+1;jingdu < 50;jingdu++)
{
yushu[jingdu] = 0;
}
break;
}
count++;
i = length,j = b.length;
for(;i >= min && j > 0;i--,j--)
{
a[i] -= b.a[j];
}
i = length;
for (i; i >= min; i--)
{
if (a[i] < 0) //補位運算
{
a[i] += 10;
a[i - 1] -= 1;
}
}
i = min;
if (a[i] == 0 && i != length)
{
while(a[i] == 0)
{
i++;
}
}
min = i;//如果有減到前面為0,最小下標右移到不為0的位置
flag = Compare(*this,b);//比較兩個數的大小
}
yushu[jingdu] = count;
jingdu++;
}
}
if(mm)
break;
}
}
return *this;
}
int Compare(CDashu a,CDashu b)
{
int i = a.min, j = 1,flag = 1;
if(a.length-a.min + 1 < b.length)
flag = 0;
else if(a.length-a.min+1 > b.length)
flag = 1;
else
{
while (a.a[i] == b.a[j] && i <= a.length && j <= b.length)
{
i++;
j++;
}
if (a.a[i] < b.a[j])
flag = 0;
if(a.a[i] == b.a[i])
{
flag = 2;
}
}
return flag;
}
CDashu::~CDashu()
{
}原文鏈接：https://blog.csdn.net/m0_60259116/article/details/128268707
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