C++实现四则混合运算计算器

本文实例为大家分享了C++实现四则混合运算的计算器,供大家参考,具体内容如下

计算器是带括号的四则运算实际上利用的是栈后进先出的原则

转换思想:

#define _CRT_SECURE_NO_WARNINGS 1

#include"stdio.h"

#include"stdlib.h"

#include"string.h"

#define maxsize 1024

typedef struct

{

float data[maxsize];

int top;

}Stack1;

void Initstack1(Stack1 *S)

{

S = (Stack1*)malloc(sizeof(Stack1));

S->top = -1;

}

int Push1(Stack1 *S, float ch)

{

if (S->top == maxsize - 1)

return 0;

else

{

S->top++;

S->data[S->top] = ch;

return 1;

}

}//入栈Push

int Pop1(Stack1 *S, float ch)

{

if (S->top == -1)

printf("栈上溢出!\n");

else

ch = S->data[S->top];

S->top--;

return 1;

}//出栈

typedef struct

{

char data[maxsize];

int top;

}Stack2;

void Initstack2(Stack2 *S)

{

S = (Stack2*)malloc(sizeof(Stack2));

S->top = -1;

}

int Push2(Stack2 *S, char ch)

{

if (S->top == maxsize - 1)

return 0;

else

{

S->top++;

S->data[S->top] = ch;

return 1;

}

}//入栈Push

int Pop2(Stack2 *S, char ch)

{

if (S->top == -1)

printf("栈上溢出!\n");

else

ch = S->data[S->top];

S->top--;

return 1;

}//出栈

int Comop(char ch) //判断是否是运算符

{

switch (ch)

{

case'+':

case'-':

case'*':

case'/':

case'(':

case')':

case'#':

return 1;

default:

return 0;

}

}//判断ch是否为运算符

char Prior[7][7] =

{ // 运算符优先级表

// '+' '-' '*' '/' '(' ')' '#'

/*'+'*/{ '>', '>', '<', '<', '<', '>', '>' },

/*'-'*/{ '>', '>', '<', '<', '<', '>', '>' },

/*'*'*/{ '>', '>', '>', '>', '<', '>', '>' },

/*'/'*/{ '>', '>', '>', '>', '<', '>', '>' },

/*'('*/{ '<', '<', '<', '<', '<', '=', '< ' },

/*')'*/{ '>', '>', '>', '>', ' ', '>', '>' },

/*'#'*/{ '<', '<', '<', '<', '<', '> ', '=' },

};

int Opid(char op1)

{

switch (op1)

{

case'+':return 0;

case'-':return 1;

case'*':return 2;

case'/':return 3;

case'(':return 4;

case')':return 5;

case'#':return 6;

default:return -123456;

}

}

char Precede(char op1, char op2) //优先级比较

{

int a, b;

a = Opid(op1); b = Opid(op2);

return(Prior[a][b]);

}

float Operation(float a, char op, float b)

{

switch (op)

{

case '+':

return b + a;

case '-':

return b - a;

case '*':

return b * a;

case '/':

return b / a;

default:

return -123456;

}

}

void CreateExpression(char *exp)

{

if (exp == NULL)

{

exit(1);

}

scanf("%s", exp);

}

void TransmitExpression(char *exp, char postexp[]) //中缀表达式转换后缀表达式

{

Stack2 FZ;

Initstack2(&FZ);

int i = 0;

char x;

FZ.top = -1;

Push2(&FZ, '#');

FZ.data[FZ.top] = '#';

while (*exp != '\0')

{

if (!Comop(*exp))

{

while (*exp >= '0'&&*exp <= '9')//读取一个数字串

{

postexp[i++] = *exp;

exp++;

}

postexp[i++] = '#';

}

else

switch (Precede(FZ.data[FZ.top], *exp))

{

case'<':

Push2(&FZ, *exp);

exp++;

break;

case'=':

x = FZ.data[FZ.top];

Pop2(&FZ, x);

exp++;

break;

case'>':

postexp[i++] = FZ.data[FZ.top];

x = FZ.data[FZ.top];

Pop2(&FZ, x);

break;

}

}

while (FZ.data[FZ.top] != '#')

{

postexp[i++] = FZ.data[FZ.top];

x = FZ.data[FZ.top];

Pop2(&FZ, x);

}

postexp[i] = '\0';

}

float EvaluateExpression(char *postexp) //后缀表达式的计算

{

Stack1 SZ;

Initstack1(&SZ);

float a, b, d;

SZ.top = -1;

while (*postexp != '\0')

{

switch (*postexp)

{

case'+':

case'-':

case'*':

case'/':

a = SZ.data[SZ.top];

Pop1(&SZ, a);

b = SZ.data[SZ.top];

Pop1(&SZ, b);

Push1(&SZ, Operation(a, *postexp, b));

break;

default:

d = 0;

while (*postexp >= '0'&&*postexp <= '9')

{

d = 10 * d + *postexp - '0';

postexp++;

}

Push1(&SZ, d);

SZ.data[SZ.top] = d;

break;

}

postexp++;

}

return(SZ.data[SZ.top]);

}

int Error(char *exp) //错误表达式判断

{

int i = 0;

while (exp[i] != '\0')

{

if (

((exp[i] == '+' || exp[i] == '-' || exp[i] == '*' || exp[i] == '/') && (exp[i + 1] == ')'))

|| ((exp[i] == '+' || exp[i] == '-' || exp[i] == '*' || exp[i] == '/') && (exp[i - 1] == '('))

|| (exp[i] == ')'&&exp[i + 1] == '(')

|| (exp[i] == '('&&exp[i + 1] == ')')

|| ((exp[i] == ')') && exp[i + 1] >= '0'&&exp[i + 1] <= '9')

|| (exp[i] >= '0'&&exp[i] <= '9'&&exp[i + 1] == '(')

|| (exp[0] == '+' || exp[0] == '-' || exp[0] == '*' || exp[0] == '/' || exp[0] == ')')

|| ((exp[i] == '+' || exp[i] == '-' || exp[i] == '*' || exp[i] == '/') && (exp[i + 1] == '+' || exp[i + 1] == '-' || exp[i + 1] == '*' || exp[i + 1] == '/'))

|| (exp[i] == '/'&&exp[i + 1] == '0')

)

return 1;

else

if (exp[i] == '\0')

return 0;

i++;

}

return 0;

}

void menu()

{

printf("\t\t--------------------------------------------\n");

printf("\t\t| 计算器 |\n");

printf("\t\t| ---------------- |\n");

printf("\t\t| | | |\n");

printf("\t\t| ---------------- |\n");

printf("\t\t| 1 2 3 + |\n");

printf("\t\t| 4 5 6 - |\n");

printf("\t\t| 7 8 9 * |\n");

printf("\t\t| 0 ( ) / |\n");

printf("\t\t--------------------------------------------\n");

printf("\t\t 请输入你要进行的操作:\n");

printf("\t\t a表达式求值 b清空 c退出\n");

}

void clear()

{

system("cls");

menu();

}

void Quit()

{

system("cls");

exit(1);

}

void main()

{

char c;

char exp[maxsize];

char postexp[maxsize] = { 0 };

menu();

while (1)

{

scanf("%c", &c);

switch (c)

{

case 'a':

sr :

printf("请输入要计算的表达式:\n");

CreateExpression(exp);

if (!Error(exp))

{

TransmitExpression(exp, postexp);

printf("后缀表达式为:%s\n", postexp);

printf("表达式结果为:%s=", exp);

printf("%g\n", EvaluateExpression(postexp));

break;

}

else

if (Error(exp))

{

printf("您输入的表达式有误!\n");

goto sr;//goto语句在循环体里进行跳转

}

case'b':

clear();

break;

case'c':

Quit();

break;

}

}

system("pause");

}

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