不多贅言。

#include <stdio.h>
#include <ctype.h>

int main(int argc, char const *argv[])
{
    char ch,prev='\n';
    int startWord = 0;
    int wordlen=0; // 單個單詞長度
    int wordcount=0; // 總單詞數量
    int totallen=0; // 總單詞長度
    int avglen = 0;
    while ( (ch = getchar())!= EOF ){
        // printf("ch = %c , ispunct(%c) ==%d\n", ch,ch,ispunct(ch));
 

        if ( isalpha(ch) && startWord ){
            // startWord = 0;
            wordlen += 1;
        }
        if ( isalpha(ch) && !startWord){
            startWord = 1; // startWord now
            wordlen = 1;
        }
        if( !isalpha(ch) && startWord && isalpha
 
(prev) ){
            wordcount +=1;
            totallen += wordlen;
            startWord =0;
            // printf(" -------- 第 %d 個單詞的長度是%d\n",wordcount,wordlen );
        }
        prev=ch;
    }
    printf("\n");
    avglen = wordcount==0?0:totallen/wordcount;
    printf("單詞數量=%d , 單詞總長度=%d ,單詞平均長度=%d \n"
 
,wordcount,totallen,avglen);

    return 0;
}

執行效果：

gcc -o ww words.c
./ww < article.txt

單詞數量=27 , 單詞總長度=160 ,單詞平均長度=5