设计模式DP-表驱动模式

• 静态结构体数组式构建
• 链表式构建
• 链接式构建

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
	
// 加 
double fun_add(double data_front, double data_back)
{
	return data_front + data_back;
}
// 减 
double fun_sub(double data_front, double data_back)
{
	return data_front - data_back;
}
// 乘 
double fun_mul(double data_front, double data_back)
{
	return data_front * data_back;
}
// 除 
double fun_div(double data_front, double data_back)
{
	if(0 == data_back) return 0;
	return data_front / data_back;
}
	
// 定义表驱动数据结构 
typedef struct {
	char *id;
	double (*callback)(double, double);
}test_fun;

// 初始化表 
const test_fun fun_table[] = {
	{"+", fun_add}, // id, callback function
	{"-", fun_sub},
	{"*", fun_mul},
	{"/", fun_div}
};
// 计算表长度 
int fun_table_len = sizeof(fun_table) / sizeof(fun_table[0]); // 计算表长度 

// 遍历表id， 执行对应function 
double cal_fun(const char *id, double data_front, double data_back) {
	for (int i= 0; i < fun_table_len; i++) {
		if (strcmp(fun_table[i].id, id) == 0) {
			return fun_table[i].callback(data_front, data_back);
		}
	}
	return 0;
}
	
// if else方法，判断运算符，执行对应函数 
double cal_fun_if(const char *id, double data_front, double data_back) 
{
	if (strcmp("+", id) == 0) { 	   // +
		return fun_add(data_front, data_back);
	} else if (strcmp("-", id) == 0) { // -
		return fun_sub(data_front, data_back);
	} else if (strcmp("*", id) == 0) { // *
		return fun_mul(data_front, data_back);
	} else if (strcmp("/", id) == 0){  // /
		return fun_div(data_front, data_back);
	}  
	return 0;
}
	
int main(int argc, char *argv[]) 
{
	// test this
	double front = 20, back = 5;

	printf("if-else Methods test as follow: \n");
	printf("%.2f + %.2f = %.2f\n", front, back, cal_fun_if("+", front, back));
	printf("%.2f - %.2f = %.2f\n", front, back, cal_fun_if("-", front, back));
	printf("%.2f * %.2f = %.2f\n", front, back, cal_fun_if("*", front, back));
	printf("%.2f / %.2f = %.2f\n", front, back, cal_fun_if("/", front, back));
	printf("\n");
	printf("Table-Driven Methods test as follow: \n");
	printf("%.2f + %.2f = %.2f\n", front, back, cal_fun("+", front, back));
	printf("%.2f - %.2f = %.2f\n", front, back, cal_fun("-", front, back));
	printf("%.2f * %.2f = %.2f\n", front, back, cal_fun("*", front, back));
	printf("%.2f / %.2f = %.2f\n", front, back, cal_fun("/", front, back));
}

• ()[https://zhuanlan.zhihu.com/p/615915687]
• ()[https://blog.csdn.net/qq_33471732/article/details/113787734]