#include #define TRUE 1

#define FALSE 0

#define LEN 10//输入数字不得超过10位

#define MAXSIZE 40//数字和运算符总个数不得超过40个

typedef struct

{

char data[MAXSIZE][LEN];//栈区为二维数组

int top;

}seqstack;

seqstack *initseqstack();

void push(seqstack *s, char *x);

char *pop(seqstack *s);

int optr(char *z);

int priority(char *a, char *b);

void process(char arrOne[][LEN], char arrTwo[][LEN]);

double calc(char *a, char *b, char *ch);

void express(char (*arrTwo)[LEN]);

seqstack *s = NULL;//声明全局变量

seqstack *initseqstack()//初始化栈顶指针

{

seqstack *s = (seqstack *) malloc (sizeof(seqstack));

s->top = -1;

return s;

}

void push(seqstack *s, char *x)//入栈

{

if (MAXSIZE-1 == s->top)

{

printf("overflow\n");

exit(0);

}

strcpy(s->data[++s->top], x);

}

char *pop(seqstack *s)//出栈

{

char *y = (char *) malloc (LEN * sizeof(char));

strcpy(y, s->data[s->top--]);

return y;

}

int optr(char *z)//判断是否为运算符，是返回TRUE

{

int i;

char *optr1[6] = {"+", "-", "*", "/", "(", ")"};

for (i=0; i<6; i++)

{

if (0 == strcmp(optr1[i], z))

{

return TRUE;

}

}

return FALSE;

}

int priority(char *a, char *b)//比较优先级

{

int i, j;

char *array[5] = {"(", "+", "-", "*", "/"};//优先级列表，由小到大

for (i=0; i<5; i++)

{

if (0 == strcmp(array[i], a))

{

break;

}

}

for (j=0; j<5; j++)

{

if (0 == strcmp(array[j], b))

{

break;

}

}

switch (i)

{

case 0: i = 0; break;

case 1:

case 2: i = 1; break;

case 3:

case 4: i = 2; break;

}

switch (j)

{

case 0: j = 0; break;

case 1:

case 2: j = 1; break;

case 3:

case 4: j = 2; break;

}

if (i >= j)

{

return TRUE;

}

else

{

return FALSE;

}

}

void process(char (*arrOne)[LEN], char (*arrTwo)[LEN])//将中缀式处理成后缀式(运算符入栈处理)

{

int i, j = 0;

s = initseqstack();//初始化

for (i=0; 0!=strcmp(arrOne[i], "\0"); i++)

{

if (1 < strlen(arrOne[i]) || (TRUE != optr(arrOne[i])))//arrOne[i][LEN]为数字时

{

strcpy(arrTwo[j++], arrOne[i]);//将数字拷贝到arrTwo

}

else if (0 == strcmp(arrOne[i], "("))

{

push(s, arrOne[i]);//入栈

}

else if (0 == strcmp(arrOne[i], ")"))

{

while ((-1 != s->top) && (0 != strcmp(s->data[s->top], "(")))

{

strcpy(arrTwo[j++], pop(s));//出栈

}

pop(s);//将"("弹出

}

else//此时arrOne的内容只可能是"+", "-", "*", "/"

{

if (-1 == s->top)

{

push(s, arrOne[i]);

}

else

{

while (-1 != s->top)

{

if (TRUE == priority(s->data[s->top], arrOne[i]))//与栈顶元素进行优先级比较

{

strcpy(arrTwo[j++], pop(s));

}

else

{

push(s, arrOne[i]);

break;

}

}

if (-1 == s->top)

{

push(s, arrOne[i]);

}

}

}

}

while (-1 != s->top)

{

strcpy(arrTwo[j++], pop(s));

}

}

double calc(char *a, char *b, char *ch)//运算，返回double类型

{

double num;

double numOne, numTwo;

numOne = atof(a);

numTwo = atof(b);//将字符串转化为double类型(atof是库函数)

switch(*ch)

{

case '+': num = numOne + numTwo; break;

case '-': num = numOne - numTwo; break;

case '*': num = numOne * numTwo; break;

case '/':

if ((0.000001 >= numTwo) && (-0.000001 <= numTwo))

{

printf("error!\n");

}

else

{

num = numOne / numTwo;

}

break;

default:

exit(0);

}

return num;

}

void express(char (*arrTwo)[LEN])//后缀式入栈运算

{

int i;

double num;

char result[LEN];

char numOne[LEN], numTwo[LEN];

s = initseqstack();//初始化

for (i=0; 0!=strcmp(arrTwo[i], "\0"); i++)

{

if (TRUE != optr(arrTwo[i]))//假如是数，则入栈

{

push(s, arrTwo[i]);

}

else

{

strcpy(numTwo, pop(s));

strcpy(numOne, pop(s));//将顶上两数字弹出

num = calc(numOne, numTwo, arrTwo[i]);//运算

gcvt(num, LEN, result);//将double转换成字符串(gcvt是库函数)

push(s, result);//入栈

}

}

printf(" %s\n\n", result);//输出最终结果

}

void Menu(void)

{

printf("注意:\n");

printf("1.本程序有一定误差，误差范围大约是-0.001到+0.001\n");

printf("2.本程序只能处理正确的表达形式.\n");

printf("3.避免计算结果越界.\n");

printf("4.输入方式:如输入表达式(-1+2)*3\n");

printf(" 输入:\n");

printf(" (空格-1空格+空格2空格)空格*空格3空格=回车\n");

}

void main(void)

{

int i = 0;

char arr[MAXSIZE][LEN]; //输入字符串

char arrOne[MAXSIZE][LEN] = { "\0" }; //保存中缀式

char arrTwo[MAXSIZE][LEN] = { "\0" }; //保存后缀式

Menu();

printf("\n\n\n请输入表达式:\n");

while (scanf("%s", arr[i]))

{

if (0 == strcmp(arr[i], "="))

{

break;

}

strcpy(arrOne[i], arr[i]);

i++;

}

process(arrOne, arrTwo); //调用

express(arrTwo); //调用

}