利用数组栈将中缀表达式转换成后缀表达式

#include <stdio.h>#include <stdlib.h>#include <string.h>typedef struct Mystack *Stack;struct Mystack {    int Capacity;       /* 栈的容量 */    int Top_of_stack;   /* 栈顶下标 */    char *Array;        /* 存放栈中元素的数组 */};/* 栈的创建 */Stack CreateStack(int Max){    Stack S;    S = malloc(sizeof(struct Mystack));    if (S == NULL)        printf("Create stack error!\n");    S->Array = malloc(sizeof(char) * Max);    if (S->Array == NULL)        printf("Create stack error!\n");    S->Capacity = Max;    S->Top_of_stack = 0;    return S;}/* 释放栈 */void DisposeStack(Stack S){    if (S != NULL)    {           free(S->Array);        free(S);    }   }/* 判断一个栈是否是空栈 */int IsEmpty(Stack S){    return !S->Top_of_stack;}/* 判断一个栈是否满栈 */int IsFull(Stack S){    if (S->Top_of_stack == S->Capacity - 1)        return 1;    else        return 0;}/* 数据入栈 */int Push(int x, Stack S){    if (IsFull(S))        printf("The Stack is full!\n");    else        S->Array[S->Top_of_stack++] = x;}/* 数据出栈 */int Pop(Stack S){    if (IsEmpty(S))        printf("The Stack is empty!\n");    else        S->Top_of_stack--;}/* 将栈顶返回 */char Top(Stack S){    if (!IsEmpty(S))        return S->Array[S->Top_of_stack-1];    printf("The Stack is empty!\n");    return 0;}/* 计算优先级 */int getPriority(char a){    switch(a)    {        case '#':            return 0;            break;        case '+':        case '-':            return 1;            break;        case '*':        case '/':            return 2;            break;        case '(':            return 3;            break;        default:            break;    }}int main(){    int i, len;    char str[100];    printf("Please input the Infix expression that you want to change: \n");    scanf("%s", str);    len = strlen(str);    /* 根据序列的长度来创建栈 */    struct Mystack *my_stack = CreateStack(len+1);    /* 利用‘#’是为了第一进栈时能方便统一的进行判断 */    Push('#', my_stack);    for (i = 0; i < len; i++)    {        if ((str[i] >= '0' && str[i] <= '9') || (str[i] >= 'a' && str[i] <= 'z'))   /* 操作数 */        {            printf("%c", str[i]);        }        else if (str[i] != ')' && getPriority(str[i]) > getPriority(Top(my_stack))) /* 当栈顶元素优先级比下一个操作符优先级小时，把外面的操作符直接进栈 */        {            Push(str[i], my_stack);        }        else if (str[i] != ')' && getPriority(str[i]) <= getPriority(Top(my_stack)))/* 栈顶元素优先级大于等于下一个操作符的优先级，这时要出栈，但要确保'('不出栈 */        {            while(getPriority(str[i]) <= getPriority(Top(my_stack)) && Top(my_stack) != '(' )            {                printf("%c", Top(my_stack));                Pop(my_stack);            }            Push(str[i], my_stack);        }        else if (str[i] == ')')     /* 如果遇见一个右括号，那么就将栈顶元素弹出，直至遇见一个左括号为止 */        {            while (Top(my_stack) != '(')            {                printf("%c", Top(my_stack));                Pop(my_stack);            }            Pop(my_stack);        }    }    /* 输出栈中剩余的元素 */    if (!IsEmpty(my_stack))    {        while (Top(my_stack) != '#')        {            printf("%c", Top(my_stack));            Pop(my_stack);        }        printf("\n");    }    DisposeStack(my_stack);    return 0;}

测试数据：

shang@shang:~/C$ ./a.outPlease input the Infix expression that you want to change:a+b*c+(d*e+f)*gabc*+de*f+g*+