字符串按word反转

方法一、不用栈

void reverseChar(char* str, int len)
{
	char* q = str+len-1;
	char* p = str;

	if (!len)
		return;

	while( p<q )
	{
		char tmp = *p;
		*p = *q;
		*q = tmp;
		p++;
		q--;
	}

	for (int i=0; i<len; i++)
		cout << str[i];
	cout << endl;
}

void reverseWord(char* str)
{
	char* p = str;
	int count = 0;
	int total = 0;

	while(1)
	{
		p++;
		count++;
		total++;

		if ( *p==' ' || *p=='\0' )
		{
			reverseChar(p-count, count);
			//note that, it is -1,not 0
			count=-1;
			
			if ( *p=='\0' )
			{
				break;
			}
		}
	}

	reverseChar(str, total);
}

　　

方法二、采用了两个stack，一个用于整个字符串的反转，一个用于保证word内部顺序不变。

 

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char* reverse_word(char* str) {     stack<char> st;     stack<char> word;        char* p = str;        st.push('\0');     while( *p != '\0')     {         while( *p == ' ')             st.push(*p++);            if ( *p == '\0')             break;            while( *p != '\0' && *p != ' ')             word.push(*p++);            while( !word.empty() )         {             st.push( word.top() );             word.pop();         }     }        p = str;     while( *p != '\0' )     {         *p = st.top();         st.pop();         p++;     }        return str; }