C++实现计算器（四则混合运算）

﹏ヽ暗。殇╰゛Y 2022-06-15 23:47 290阅读 0赞

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  
![这里写图片描述][SouthEast]

![这里写图片描述][SouthEast 1]

转换思想：  
![这里写图片描述][SouthEast 2]

#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");
    }

[SouthEast]: /images/20220616/0594558ff80d4f4d91c905d10413f976.png
[SouthEast 1]: /images/20220616/c646e496d5e54f8c89cb84ddce0e4b4b.png
[SouthEast 2]: /images/20220616/11b3fc8422864045af2275c994af271f.png