if...else...面条代码，以及三种实现方式

由于本人从事业务层代码编写，每次都是if...else... 面条代码较多，本次随笔主要是记录三种写代码方式，满足a条件，调用执行a的函数，满足b条件，调用执行b的函数，满足c条件，调用执行c的函数
三种代码实现方式都是实现同一功能，代码可以直接运行；

1.采用挂钩子形式，开放注册接口，系统运行时每个模块依次判断条件并且执行该模块的操作，
有兴趣的可以将注册的函数挂载在全局变量下，这样便于各个共享模块注册，这里只是提供大概模型；

#include<stdio.h>
#include <stdlib.h>
#include <string.h>
#define MAX_EXECUTE_FUNC_NUM 10

typedef int(*JUDGE_FUNC)(char para1, int para2, int para3, int para4);
typedef int(*EXECUTE_FUNC)(int para1, int para2, int para3, int para4);

int mount_judge_func(JUDGE_FUNC *judge_func, JUDGE_FUNC func1, JUDGE_FUNC func2, JUDGE_FUNC func3)
{
	if((NULL == judge_func)
		|| (NULL == func1)
		|| (NULL == func2)
		|| (NULL == func3))
	{
		return -1;
	}
	
	judge_func[0] = func1;
	judge_func[1] = func2;
	judge_func[2] = func3;
	
	return 0;
}

int mount_execute_func(EXECUTE_FUNC *execute_func, EXECUTE_FUNC func1, EXECUTE_FUNC func2, EXECUTE_FUNC func3)
{
	if((NULL == execute_func)
		|| (NULL == func1)
		|| (NULL == func2)
		|| (NULL == func3))
	{
		return -1;
	}
	execute_func[0] = func1;
	execute_func[1] = func2;
	execute_func[2] = func3;
	return 0;
}

int judge_func_a(char para1, int para2, int para3, int para4)
{
	if(para1 == 'a')
	{
		return 0;
	}

	return -1;
}

int judge_func_b(char para1, int para2, int para3, int para4)
{
	if(para1 == 'b')
	{
		return 0;
	}

	return -1;
}

int judge_func_c(char para1, int para2, int para3, int para4)
{
	if(para1 == 'c')
	{
		return 0;
	}

	return -1;
}

int execute_func_a(int para1, int para2, int para3, int para4)
{
	printf("execute execute_func_a
");

	return 0;
}

int execute_func_b(int para1, int para2, int para3, int para4)
{
	printf("execute execute_func_b
");

	return 0;
}

int execute_func_c(int para1, int para2, int para3, int para4)
{
	printf("execute execute_func_c
");

	return 0;
}

int main()
{
	int i = 0;
	int ret = 0;
	char para1 = 0;
	int para2 = 0;
	int para3 = 0;
	int para4 = 0;
	int para5 = 0;
	int para6 = 0;
	int para7 = 0;
	int para8 = 0;

	EXECUTE_FUNC execute_func[MAX_EXECUTE_FUNC_NUM + 1] = {NULL};
	JUDGE_FUNC judge_func[MAX_EXECUTE_FUNC_NUM + 1] = {NULL};

	scanf("%c %d %d %d", &para1, &para2, &para3, &para4);

	//printf("%c, %d, %d, %d", para1, para2, para3, para4);

	ret = mount_judge_func(judge_func, judge_func_a, judge_func_b, judge_func_c);
	if(0 != ret)
	{
		printf("mount_judge_func register failed
");
		return -1;
	}

	ret = mount_execute_func(execute_func, execute_func_a, execute_func_b, execute_func_c);
	if(0 != ret)
	{
		printf("mount_execute_func register failed
");
		return -1;
	}

	for(i = 0; i < MAX_EXECUTE_FUNC_NUM; i++)
	{
		if((NULL == judge_func[i]) 
			|| (NULL == execute_func[i]))
		{
			continue;
		}

		if(0 == judge_func[i](para1, para2, para3, para4))
		{
			return execute_func[i](para5, para6, para7, para8);
		}
	}

	printf("no func execute!
");

	return 0;
} 

2.采用do...while(0), 和switch进行组合使用，也是一种使用技巧；

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

#define MAX_EXECUTE_FUNC_NUM 10
#define EXECUTE_FUNC_A       1
#define EXECUTE_FUNC_B       2
#define EXECUTE_FUNC_C       3

typedef int(*JUDGE_FUNC)(char para1, int para2, int para3, int para4);
typedef int(*EXECUTE_FUNC)(int para1, int para2, int para3, int para4);

int judge_func_a(char para1, int para2, int para3, int para4)
{
	if(para1 == 'a')
	{
		return 0;
	}

	return -1;
}

int judge_func_b(char para1, int para2, int para3, int para4)
{
	if(para1 == 'b')
	{
		return 0;
	}

	return -1;
}

int judge_func_c(char para1, int para2, int para3, int para4)
{
	if(para1 == 'c')
	{
		return 0;
	}

	return -1;
}

int execute_func_a(int para1, int para2, int para3, int para4)
{
	printf("execute execute_func_a
");

	return 0;
}

int execute_func_b(int para1, int para2, int para3, int para4)
{
	printf("execute execute_func_b
");

	return 0;
}

int execute_func_c(int para1, int para2, int para3, int para4)
{
	printf("execute execute_func_c
");

	return 0;
}

int main()
{
	int judge_ret = 0;
	int execute_ret = 0;
	char para1 = 0;
	int para2 = 0;
	int para3 = 0;
	int para4 = 0;
	int para5 = 0;
	int para6 = 0;
	int para7 = 0;
	int para8 = 0;

	scanf("%c %d %d %d", &para1, &para2, &para3, &para4);

	do{
		judge_ret = judge_func_a(para1, para2, para3, para4);	
		if(0 == judge_ret)
		{
			execute_ret = EXECUTE_FUNC_A;
			break;
		}

		judge_ret = judge_func_b(para1, para2, para3, para4);	
		if(0 == judge_ret)
		{
			execute_ret = EXECUTE_FUNC_B;
			break;
		}

		judge_ret = judge_func_c(para1, para2, para3, para4);	
		if(0 == judge_ret)
		{
			execute_ret = EXECUTE_FUNC_C;
			break;
		}	

	}while(0);

	switch(execute_ret)
	{
		case EXECUTE_FUNC_A:
			execute_func_a(para5, para6, para7, para8);
			break;

		case EXECUTE_FUNC_B:
			execute_func_b(para5, para6, para7, para8);
			break;

		case EXECUTE_FUNC_C:
			execute_func_c(para5, para6, para7, para8);
			break;	

		default:
			printf("no func execute!
");
			break;			
	}

	return 0;
} 

3.最常见的if...else...编写代码，随着if...else...嵌套变多，可理解性变差

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

int judge_func_a(char para1, int para2, int para3, int para4)
{
	if(para1 == 'a')
	{
		return 0;
	}

	return -1;
}

int judge_func_b(char para1, int para2, int para3, int para4)
{
	if(para1 == 'b')
	{
		return 0;
	}

	return -1;
}

int judge_func_c(char para1, int para2, int para3, int para4)
{
	if(para1 == 'c')
	{
		return 0;
	}

	return -1;
}

int execute_func_a(int para1, int para2, int para3, int para4)
{
	printf("execute execute_func_a
");

	return 0;
}

int execute_func_b(int para1, int para2, int para3, int para4)
{
	printf("execute execute_func_b
");

	return 0;
}

int execute_func_c(int para1, int para2, int para3, int para4)
{
	printf("execute execute_func_c
");

	return 0;
}

int main()
{
	int execute_ret = 0;
	char para1 = 0;
	int para2 = 0;
	int para3 = 0;
	int para4 = 0;
	int para5 = 0;
	int para6 = 0;
	int para7 = 0;
	int para8 = 0;

	scanf("%c %d %d %d", &para1, &para2, &para3, &para4);

	if(0 == judge_func_a(para1, para2, para3, para4))
	{
		execute_ret = execute_func_a(para5, para6, para7, para8);
	}
	else if(0 == judge_func_b(para1, para2, para3, para4))				
	{
		execute_ret = execute_func_b(para5, para6, para7, para8);
	}
	else if(0 == judge_func_c(para1, para2, para3, para4))				
	{
		execute_ret = execute_func_c(para5, para6, para7, para8);
	}
	else
	{
		printf("no func execute!
");
	}

	return execute_ret;
}