【数据结构】利用栈 求解表达式

表达式求值问题，其中运算符号只包含 加减乘除 取整数 详细请参见代码：

#include <stdio.h>#define MAX_SIZE 100typedef struct {int top;char data[MAX_SIZE];}NumStack;typedef struct {int top;char opera[MAX_SIZE];}OperaStack;const char perior[5][5] = {'>','>','<','<','>','>','>','<','<','>','>','>','>','>','>','>','>','>','>','>','<','<','<','<','<',};void NumPush(NumStack* L,int elem);void OperaPush(OperaStack* L, char elem);int NumPop(NumStack* L);char OperaPop(OperaStack* L);char comp_perior(char a,char b);int compute(int a,int b,char c);int pe2int(char a);void main(){int i = 0;int j = 0;int num = 0;char expression[20] = "14+13-2*9+24/3=";NumStack Num_stack = {0,};OperaStack Opera_stack = {0,};while (expression[i] != '\0'){switch (expression[i]){case '0':case '1':case '2':case '3':case '4':case '5':case '6':case '7':case '8':case '9':num = 10*num + (expression[i]-'0');break;case '=':if (expression[i+1] != '\0')return;case '+':case '-':case '*':case '/':NumPush(&Num_stack,num);if (Opera_stack.top == 0 || comp_perior(Opera_stack.opera[Opera_stack.top-1],expression[i]) == '<')OperaPush(&Opera_stack,expression[i]); // 栈空时直接入栈else {do{int temp = compute(NumPop(&Num_stack),NumPop(&Num_stack),OperaPop(&Opera_stack));NumPush(&Num_stack,temp);}while (comp_perior(Opera_stack.opera[Opera_stack.top-1],expression[i]) == '>');OperaPush(&Opera_stack,expression[i]);}num = 0;break;}i++;}printf("计算的结果 = %d\n",Num_stack.data[Num_stack.top-1]);}void NumPush(NumStack* L,int elem){if (L->top+1 < MAX_SIZE)L->data[L->top++] = elem;}void OperaPush(OperaStack* L, char elem){if ((L->top+1) < MAX_SIZE)L->opera[L->top++] = elem;}int NumPop(NumStack* L){if (L->top == 0)return -1;return (L->data[--L->top]);}char OperaPop(OperaStack* L){if (L->top == 0)return -1;return (L->opera[--L->top]);}char comp_perior(char a,char b){return perior[pe2int(a)][pe2int(b)];}int pe2int(char a){switch (a){case '+':return 0;case '-':return 1;case '*':return 2;case '/':return 3;case '=':return 4;default:return -1;}}int compute(int a,int b,char c){switch(c){case '+':return a+b;case '-':return a-b;case '*':return a*b;case '/':return a/b;}}