计算字符串中的子字符串字符

Question

I'm writing a function that takes an input string consisting of a mix 'o' 'g' and 'c'. For each of these characters in the string, a certain symbol is printed. However, for the 'g' character, id like to count how many g's are in a row in the string. Here is the code I have so far:

void printSymbol(char *str) // takes
{
  int i; // counter for entire string
  int k; // counter for substring ('g' char)
  int count = 0; //stores amount of consecutive g's in substring

  for (i = 0; str[i] != '\0'; i++) //looping until null term.
  {
    if (str[i] == 'o')
      printf("==========\n"); //symbol for o
    if (str[i] == 'c')
      printf(" ~~~~~~~~ \n"); //symbol for c
    if (str[i] == 'g') //if character is g
    {
      for(k = i; str[k] == 'g'; k++) //will loop through string starting at first g until next character is NOT g
      {
        count++; //count amount of consecutive g
      }
      printf("%d\n", count); //printing number of g's in a row
      if (count % 3 == 2) //All of these if statements are printing.
        printf("R==2\n");
      if (count % 3 == 1)
        printf("R == 1\n");
      if (count % 3 == 0)
        printf("R == 0\n");

      count = 0; // resets count for next set of consecutive g's in string
    }
  }
}

The problem I'm having is that it is printing all if statements in the for loop for the g char. If there are 3 g's in a row, it will print R = 0, then R = 2, and R = 1, because it will loop through each g and thus the remainder is changing. How do I stop this? Id like to record the remainder for the entire set of consecutive g's one time. So if there are 3 g's, Id like to print R = 0, and then reset the counter var.

Answer 1

You are not updating your i variable when checking for consecutive g characters. Your inner for loop that checks for consecutive g characters uses a separate loop variable, k , but since the i variable (the main loop counter) is not updated, then the string of consecutive g characters would be checked multiple times.

Eg

Assume your string is "...ggg...". Then the first time you encounter this string, the inner for loop will check for the number of g characters and find that it is 3. It will then print out R == 0 , reset the count to 0 and go back to the main for loop.

However, the outer for loop would then see the string as "gg..." and it will once again enter the inner for loop. This time, count would be 2 and R == 2 would be printed out.

This process would then repeat for the final time. The string to be processed is "g...". This time, the count would be 1 and R == 1 would get printed out.

To solve this, you simply have to update your i variable by adding the number of g characters you found - 1 (since the loop counter would increment at the end of the loop).