用c语言写一个生成逆波兰式

以下是一个简单的生成逆波兰式的 C 语言程序：

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

#define MAX_STACK_SIZE 100

char stack[MAX_STACK_SIZE][MAX_STACK_SIZE];
int top = -1;

void push(char* item)
{
    if (top >= MAX_STACK_SIZE - 1) {
        printf("Stack Overflow\n");
        return;
    }
    top++;
    strcpy(stack[top], item);
}

char* pop()
{
    if (top == -1) {
        printf("Stack Underflow\n");
        return NULL;
    }
    char* item = stack[top];
    top--;
    return item;
}

int is_operator(char* symbol)
{
    if (strcmp(symbol, "+") == 0 || strcmp(symbol, "-") == 0 || strcmp(symbol, "*") == 0 || strcmp(symbol, "/") == 0) {
        return 1;
    }
    return 0;
}

int precedence(char* symbol)
{
    if (strcmp(symbol, "*") == 0 || strcmp(symbol, "/") == 0) {
        return 2;
    }
    else if (strcmp(symbol, "+") == 0 || strcmp(symbol, "-") == 0) {
        return 1;
    }
    return 0;
}

void infix_to_postfix(char* infix_expression, char* postfix_expression)
{
    int i = 0, j = 0;
    char* symbol;
    while (infix_expression[i] != '\0') {
        symbol = (char*)malloc(MAX_STACK_SIZE * sizeof(char));
        while (infix_expression[i] == ' ' || infix_expression[i] == '\t') {
            i++;
        }
        symbol[0] = infix_expression[i];
        if (isdigit(infix_expression[i])) {
            j = i + 1;
            while (isdigit(infix_expression[j])) {
                j++;
            }
            strncpy(&symbol[1], &infix_expression[i + 1], j - i - 1);
            symbol[j - i] = '\0';
            strcat(postfix_expression, symbol);
            strcat(postfix_expression, " ");
            i = j;
        }
        else if (is_operator(symbol)) {
            while (top != -1 && precedence(stack[top]) >= precedence(symbol)) {
                strcat(postfix_expression, pop());
                strcat(postfix_expression, " ");
            }
            push(symbol);
            i++;
        }
        else if (symbol[0] == '(') {
            push(symbol);
            i++;
        }
        else if (symbol[0] == ')') {
            while (top != -1 && stack[top][0] != '(') {
                strcat(postfix_expression, pop());
                strcat(postfix_expression, " ");
            }
            pop();
            i++;
        }
        free(symbol);
    }
    while (top != -1) {
        strcat(postfix_expression, pop());
        strcat(postfix_expression, " ");
    }
}

int main()
{
    char infix_expression[MAX_STACK_SIZE], postfix_expression[MAX_STACK_SIZE];
    printf("Enter Infix Expression : ");
    gets(infix_expression);
    infix_to_postfix(infix_expression, postfix_expression);
    printf("Postfix Expression : %s", postfix_expression);
    return 0;
}

该程序使用栈数据结构将中缀表达式转换为逆波兰式。输入中缀表达式后，程序将空格分隔的逆波兰式输出到屏幕上。