为什么我的程序无法计算字符串中的单词？

Question

Just so you know, this isn't a homework problem. I'm trying to practice by writing more programs on my own. So, I have to write a program that counts the number of words in a string. I've used the relationship between the number of spaces and the number of words in a sentence for my program. (the number of words seems to be one more than the number of spaces in a sentence). But, when I tried testing it, the compiler said that the string "Apple juice" only had 1 word. :( I'm not sure why my code could be wrong.

Here's my code:

int words_in_string(char str[])
{
   int spaces = 0, num_words;

   for (int i = 0; i != '\0'; i++)
   {
      if (str[i] == ' ')
      {
         spaces = spaces + 1;
      }
   }

   num_words = spaces + 1;

   return num_words;
}

Answer 1

int words_in_string(char str[])
{
   int spaces = 0, num_words;

   for (int i = 0; str[i] != '\0'; i++)
   {
      if (str[i] == ' ')
      {
         spaces = spaces + 1;
      }
   }

   num_words = spaces + 1;

   return num_words;
}

The stop condition should be

str[i] != '\0'

Answer 2

You got the code correct but assuming number of words is 1 greater than number of spaces is a faulty assumption. You can have a sentence to begin with space or end with space or both. Your logic will fail in that case.

Answer 3

int words_in_string(const char *str){
    int in_word = 0, num_words = 0;

    while(*str){
        if(isspace(*str++))
            in_word = 0;
        else{
            if(in_word == 0) ++num_words;
            in_word = 1;
        }
    }
    return num_words;
}