几个错误

题目如下：

编写子程序 int wordnum(char *p)
程序说明：
  返回*p指向的字符串中包含的单词的总数。其中，字符串为不规则字符串。单词与单词之间的划分规则,任意不为字母的字符，都可以是一个划分。
举例：
    char str1[] = "";
    char str2[] = " ,, ???, ^^&  abc! ";
    char str3[] = "   ";
    char str4[] = "I ??am? a bo^y";
    char str5[] = " my ";
    char str6[] = " Th8is is ,, ,    a?  test ! ";
     char str7[] = "Overseas  students scramble for flights home！          ";
    char str8[] = "    Whatever is worth doing is worth doing well.";
    char str9[] = "In love folly is always sweet"
其中的单词数依次为：
0      1    0   5    1      5     6     8     6
已知主函数和子函数的调用过程如下：
int main()
{

    char str1[] = "";
    char str2[] = " ,, ???, ^^&  abc! ";
    char str3[] = "   ";
    char str4[] = "I ??am? a bo^y";
    char str5[] = " my ";
    char str6[] = " Th8is is ,, ,    a?  test ! ";
    char str7[] = "Overseas  students scramble for flights home！          ";
    char str8[] = "    Whatever is worth doing is worth doing well.";
    char str9[] = "In love folly is always sweet";
     int k;
     k = wordnum(str1);
     printf("Word number: %d\n",k);
    k = wordnum(str2);
    printf("Word number: %d\n",k);
    k = wordnum(str3);
    printf("Word number: %d\n",k);
    k = wordnum(str4);
    printf("Word number: %d\n",k);
    k = wordnum(str5);
    printf("Word number: %d\n",k);
    k = wordnum(str6);
    printf("Word number: %d\n",k);
     k = wordnum(str7);
    printf("Word number: %d\n",k);
    k = wordnum(str8);
    printf("Word number: %d\n",k);
     k = wordnum(str9);
    printf("Word number: %d\n",k);

     return 0;

}

题目要求：编写完整子程序，并将程序完整程序代码 以及程序运行结果，粘贴至答案栏注意程序的格式，要符合要求。

做了好几遍，总是有几个错误地方，因为最近在读c primer plus.学会了用几个不常用的库函数 isalpha,

下面是正确答案和几个错误答案，求指教。错误的哪里出了问题：

正确

#include<stdio.h>
#include<stdlib.h>
#include<string.h>
#include<ctype.h>//函数库
int wordnum (char *p);
int main()

{

    char str1[] = "";
    char str2[] = " ,, ???, ^^&  abc! ";
    char str3[] = "   ";
    char str4[] = "I ??am? a bo^y";
    char str5[] = " my ";
    char str6[] = " Th8is is ,, ,    a?  test ! ";
    char str7[] = "Overseas  students scramble for flights home！          ";
    char str8[] = "    Whatever is worth doing is worth doing well.";
    char str9[] = "In love folly is always sweet";
    int k;
    k = wordnum(str1);
    printf("Word number: %d\n",k);
    k = wordnum(str2);
    printf("Word number: %d\n",k);
    k = wordnum(str3);
    printf("Word number: %d\n",k);
    k = wordnum(str4);
    printf("Word number: %d\n",k);
    k = wordnum(str5);
    printf("Word number: %d\n",k);
    k = wordnum(str6);
    printf("Word number: %d\n",k);
    k = wordnum(str7);
    printf("Word number: %d\n",k);
    k = wordnum(str8);
    printf("Word number: %d\n",k);
    k = wordnum(str9);
    printf("Word number: %d\n",k);
    return 0;
}
int wordnum (char *p)

{

    int word=0 ,i=0,num=0;

char c;
  for(i=0;*(p+i)!='\0';i++)
  {
      c=*(p+i);
      if(( word==0)&&(isalpha(c)))//isalpha如果是字母就返回1，else0
        num++;
      word=isalpha(c);
  }



return num;

}

错误第一次：

#include<stdio.h>
#include<stdlib.h>
#include<string.h>
int wordnum (char *p);
int main()

{

    char str1[] = "";
    char str2[] = " ,, ???, ^^&  abc! ";
    char str3[] = "   ";
    char str4[] = "I ??am? a bo^y";
    char str5[] = " my ";
    char str6[] = " Th8is is ,, ,    a?  test ! ";
    char str7[] = "Overseas  students scramble for flights home！          ";
    char str8[] = "    Whatever is worth doing is worth doing well.";
    char str9[] = "In love folly is always sweet";
    int k;
    k = wordnum(str1);
    printf("Word number: %d\n",k);
    k = wordnum(str2);
    printf("Word number: %d\n",k);
    k = wordnum(str3);
    printf("Word number: %d\n",k);
    k = wordnum(str4);
    printf("Word number: %d\n",k);
    k = wordnum(str5);
    printf("Word number: %d\n",k);
    k = wordnum(str6);
    printf("Word number: %d\n",k);
    k = wordnum(str7);
    printf("Word number: %d\n",k);
    k = wordnum(str8);
    printf("Word number: %d\n",k);
    k = wordnum(str9);
    printf("Word number: %d\n",k);
    return 0;
}
int wordnum (char *p)

{

    int word=0 ,i=0,num=0;

    char c;
/*用word做标记，初始为0，读到一个，如果是字母，并且word==0（也就是说上衣不是字母），累加。不是的话就赋值word=0；
  for(i=0;*(p+i)!='\0';i++)
  {
      c=*(p+i);
      if( (word==0)&&((c>='A'&&c<='Z')||(c>='a'&&c<='z' ) ))
      {
          num++;
          word=1;
      }
      else {word=0;}
  }



return num;

}

错误二，改用while，感觉是一个错误。

#include<stdio.h>
#include<stdlib.h>
#include<string.h>
int wordnum (char *p);
int main()

{

    char str1[] = "";
    char str2[] = " ,, ???, ^^&  abc! ";
    char str3[] = "   ";
    char str4[] = "I ??am? a bo^y";
    char str5[] = " my ";
    char str6[] = " Th8is is ,, ,    a?  test ! ";
    char str7[] = "Overseas  students scramble for flights home！          ";
    char str8[] = "    Whatever is worth doing is worth doing well.";
    char str9[] = "In love folly is always sweet";
    int k;
    k = wordnum(str1);
    printf("Word number: %d\n",k);
    k = wordnum(str2);
    printf("Word number: %d\n",k);
    k = wordnum(str3);
    printf("Word number: %d\n",k);
    k = wordnum(str4);
    printf("Word number: %d\n",k);
    k = wordnum(str5);
    printf("Word number: %d\n",k);
    k = wordnum(str6);
    printf("Word number: %d\n",k);
    k = wordnum(str7);
    printf("Word number: %d\n",k);
    k = wordnum(str8);
    printf("Word number: %d\n",k);
    k = wordnum(str9);
    printf("Word number: %d\n",k);
    return 0;
}
int wordnum (char *p)

{

    int word=0 ,i=0,num=0;

char c;
  while(c=*(p+(i++))!='\0')
  {
      if( (word==0)&&((c>='A'&&c<='Z')||(c>='a'&&c<='z' ) ))
      {
          num++;
          word=1;
      }
      else {word=0;}
  }




return num;

}