C中缀表达式转后缀表达式并求值代码

C语言中实现中缀表达式转后缀表达式并求值的代码如下所示：

#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#define MAX_SIZE 100

// 定义栈结构
typedef struct {
    char data[MAX_SIZE];
    int top;
} Stack;

// 初始化栈
void initStack(Stack *s) {
    s->top = -1;
}

// 判断栈是否为空
int isEmpty(Stack *s) {
    return s->top == -1;
}

// 判断栈是否已满
int isFull(Stack *s) {
    return s->top == MAX_SIZE - 1;
}

// 入栈
void push(Stack *s, char c) {
    if (isFull(s)) {
        printf("Stack is full.\n");
        exit(1);
    }
    s->data[++(s->top)] = c;
}

// 出栈
char pop(Stack *s) {
    if (isEmpty(s)) {
        printf("Stack is empty.\n");
        exit(1);
    }
    return s->data[(s->top)--];
}

// 获取栈顶元素
char peek(Stack *s) {
    if (isEmpty(s)) {
        printf("Stack is empty.\n");
        exit(1);
    }
    return s->data[s->top];
}

// 判断运算符的优先级
int getPriority(char c) {
    switch (c) {
        case '+':
        case '-':
            return 1;
        case '*':
        case '/':
            return 2;
        case '^':
            return 3;
        default:
            return 0;
    }
}

// 中缀表达式转后缀表达式
void infixToPostfix(char *infix, char *postfix) {
    Stack s;
    initStack(&s);
    int i, j = 0;
    for (i = 0; infix[i] != '\0'; i++) {
        if (infix[i] >= '0' && infix[i] <= '9') {
            postfix[j++] = infix[i];
        } else if (infix[i] == '(') {
            push(&s, infix[i]);
        } else if (infix[i] == ')') {
            while (!isEmpty(&s) && peek(&s) != '(') {
                postfix[j++] = pop(&s);
            }
            if (!isEmpty(&s) && peek(&s) != '(') {
                printf("Invalid expression.\n");
                exit(1);
            } else {
                pop(&s);
            }
        } else {
            while (!isEmpty(&s) && getPriority(infix[i]) <= getPriority(peek(&s))) {
                postfix[j++] = pop(&s);
            }
            push(&s, infix[i]);
        }
    }
    while (!isEmpty(&s)) {
        postfix[j++] = pop(&s);
    }
    postfix[j] = '\0';
}

// 计算后缀表达式的值
int evaluatePostfix(char *postfix) {
    Stack s;
    initStack(&s);
    int i, operand1, operand2, result;
    for (i = 0; postfix[i] != '\0'; i++) {
        if (postfix[i] >= '0' && postfix[i] <= '9') {
            push(&s, postfix[i] - '0');
        } else {
            operand2 = pop(&s);
            operand1 = pop(&s);
            switch (postfix[i]) {
                case '+':
                    result = operand1 + operand2;
                    break;
                case '-':
                    result = operand1 - operand2;
                    break;
                case '*':
                    result = operand1 * operand2;
                    break;
                case '/':
                    result = operand1 / operand2;
                    break;
                case '^':
                    result = 1;
                    while (operand2 > 0) {
                        result *= operand1;
                        operand2--;
                    }
                    break;
                default:
                    printf("Invalid expression.\n");
                    exit(1);
            }
            push(&s, result);
        }
    }
    return pop(&s);
}

int main() {
    char infix[MAX_SIZE];
    char postfix[MAX_SIZE];
    printf("Enter an infix expression: ");
    scanf("%s", infix);
    infixToPostfix(infix, postfix);
    printf("Postfix expression: %s\n", postfix);
    int result = evaluatePostfix(postfix);
    printf("Result: %d\n", result);
    return 0;
}