2020-11-16

去除C程序中的注释

总时间限制: 1000ms 内存限制: 65536kB

描述
C程序的注释用/…/来表示。请写一个程序，将输入的C程序源代码中的注释去掉，输出去掉注释之后的源代码。

用于测试的C代码保证符合语法，不使用C++的//注释语法。

注意，C语言不允许出现嵌套注释。具体来说，对于//**/"/"，如果不允许嵌套注释，那么它表示字符串"*/"；如果允许嵌套注释，它表示一个引号"。

还请注意，字符串中出现的注释符/*属于字符串的一部分，注释中出现的双引号"属于注释的一部分。

输入
符合语法的C代码文本文件。代码每行不超过200个字符。

输出
去掉注释后的C代码。要求只能去掉注释，不可以做其他的修改，比如调整缩进,去除注释之外的换行符等。

样例输入

#include 
#include 
#include 

/*Hash Search: 
Hash function: division method; 
handling collisions: open addressing's linear probing. 
In this exercise, M is the basic area's length, all keys are non negative integers.*/

#define M 11

int hash(int key)
{
	return key % M;
}

void init_hash(int* hashtable)
{
	int i;
	for(i = 0; i < M; ++i)
	{
		hashtable[i] = -1;
	}
}

/*return value: 
1:found, *position is the key's index; 
0:not found, *position is where to insert the key; 
-1:overflow. */
int search_hash(int* hashtable, int key, int* position)
{
	int i, h = hash(key);
	for(i = 0; i < M; ++i)
	{
		if(key == hashtable[h])
		{
			*position = h;
			return 1;
		}
		if(-1 == hashtable[h])
		{
			*position = h;
			return 0;
		}
		h = (h+1) % M;
	}
	*position = -1;
	return -1;
}

/*return value: 1:inserted, 0:overflow*/
int insert_hash(int* hashtable, int key)
{
	int position, result;
	result = search_hash(hashtable, key, &position);
	if(-1 == result)
		return 0;
	hashtable[position] = key;
	return 1;
}

void main()
{
	int hashtable[M];
	init_hash(hashtable);
	srand(time(NULL));
	int i, j, key;
	for(i = 0; i < 8; ++i) 	/*make a hash table with 8 elements*/
	{
		key = rand() % 50;
		insert_hash(hashtable, key);
		printf("Insert %d\n", key);
		for(j = 0; j < M; ++j)
			printf("%3d", hashtable[j]);
		printf("\n");
	}

	printf("Please input the key to search:\n");
	scanf("%d", &key);
	i = search_hash(hashtable, key, &j);
	if(1 == i)
		printf("Found!Its index is %d\n", j);
	else
		printf("Not found!\n");
}

样例输出

#include 
#include 
#include 



#define M 11

int hash(int key)
{
	return key % M;
}

void init_hash(int* hashtable)
{
	int i;
	for(i = 0; i < M; ++i)
	{
		hashtable[i] = -1;
	}
}


int search_hash(int* hashtable, int key, int* position)
{
	int i, h = hash(key);
	for(i = 0; i < M; ++i)
	{
		if(key == hashtable[h])
		{
			*position = h;
			return 1;
		}
		if(-1 == hashtable[h])
		{
			*position = h;
			return 0;
		}
		h = (h+1) % M;
	}
	*position = -1;
	return -1;
}


int insert_hash(int* hashtable, int key)
{
	int position, result;
	result = search_hash(hashtable, key, &position);
	if(-1 == result)
		return 0;
	hashtable[position] = key;
	return 1;
}

void main()
{
	int hashtable[M];
	init_hash(hashtable);
	srand(time(NULL));
	int i, j, key;
	for(i = 0; i < 8; ++i) 	
	{
		key = rand() % 50;
		insert_hash(hashtable, key);
		printf("Insert %d\n", key);
		for(j = 0; j < M; ++j)
			printf("%3d", hashtable[j]);
		printf("\n");
	}

	printf("Please input the key to search:\n");
	scanf("%d", &key);
	i = search_hash(hashtable, key, &j);
	if(1 == i)
		printf("Found!Its index is %d\n", j);
	else
		printf("Not found!\n");
}

算法：借鉴了状态机，对每种状态改变判断和输出

#include 
#include 
#include 
#include 
#include 
using namespace std;
//借鉴状态机的思想
char c = '\0';
int flag = 0;

int main() {
    while((c = getchar()) != EOF){
        if(flag == 0 && c == '/')
            flag = 1;
        else if(flag == 1 && c == '*')
            flag = 2;
        else if(flag == 1){
            putchar('/');
            flag = 0;
        }
        
        else if(flag == 2 && c == '*')
            flag = 3;
        else if(flag == 2)
            flag = 2;
        
        else if(flag == 3 && c == '/')
            flag = 0;
        else if(flag == 3 && c == '*')
            flag = 3;
        else if(flag == 3)
            flag = 2;
        
        else if(flag == 0 && c == '\'')
            flag = 5;
        else if(flag == 5 && c == '\\')
            flag = 6;
        else if(flag == 6)
            flag = 5;
        else if(flag == 5 && c == '\'')
            flag = 0;
        
        else if(flag == 0 && c == '\"')
            flag = 7;
        else if(flag == 7 && c == '\\')
            flag = 8;
        else if(flag == 8)
            flag = 7;
        else if(flag == 7 && c == '\"')
            flag = 0;
        
        if((flag == 0 && c != '/') || 5 <= flag )
            putchar(c);
        
    }
    return 0;
}