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

void main()
{
    char *str="Tom is Tom and you are you";//
    char words[100][20]={0};
    int total=0;//统计总个数
    int wordcount[100]={0};//统计单词频率

    char *p=str;
    char temp[20]={0};
    int tempcount=0;
    int i=0;
    while(p)
    {
        if(*p==' ')
        {
            for(i=0;i<total;++i)
            {
                if(strcmp(words[i],temp)==0)
                {
                    wordcount[i]++;
                }
            }
            if(i==total)
            {
                strcpy(words[total++],temp);
                strcpy(temp,"");
                tempcount=0;
            }
        }
        else
        {
            temp[tempcount++]=*p;
        }
        p++;
    }

    printf("单词总数:%d\n",total);
    for(i=0;i<total;++i)
    {
        printf("单词:%s 数量:%d\n",words[i],wordcount[i]);
    }
}

while(*p)

二维数组的输出有问题吧。。

取单词部份（其他忽略）
#include<stdio.h>
void main()
{
    char *str="Tom is Tom and you are you";//
    char *p=str;
    char temp[20];
    int n;
    while (*p)
    {
        if (sscanf(p,"%s%n",temp,&n)==1)
        {
            printf("%s\n", temp);
            p += n;
        }
        else
            ++p;
    }
}