字符串逆序

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

char *reverse(char *str, int len) //字符串倒序
{
    if (str == NULL)
    {
        return NULL;
    }
    char *pBegin = str;
    char *pLast = str;
    pLast = str + len - 1;

    while (pBegin < pLast)
    {
        char temp;
        temp = *pBegin;
        *pBegin = *pLast;
        *pLast = temp;

        pBegin++;
        pLast--;
    }
    return str;
}

char *ReverseSentence(char *str)  //倒序句子
{
    if (str == NULL)
    {
        return NULL;
    }
    reverse(str, strlen(str));  //逆转句子

    char *pBegin = str;
    char *pEnd = str;
    while (*pEnd != '\0')
    {
        while (*pEnd != '\0' && *pEnd != ' ')
        {
            pEnd++;
        }
        
        reverse(pBegin, pEnd - pBegin); //逆转每个单词
      
        if (*pEnd == '\0')
        {
            break;
        }
        pEnd++;
        pBegin = pEnd;
        
    }
    return str;
    
}

int main()
{
    char ch[] = "Hello World";
    printf ("ch = %s\n", ch);
 
    printf ("ch_now = %s\n", ReverseSentence(ch));
}