a function produces an inifinite loop - c

Question

I wrote the following function and when I run it , it produces an infinite loop and I dont understand why.
This function creates a dynamic array of dynamic strings. Every such string starts with a letter given, or with a capital letter which is compatible to the letter given:
void wordsStartWithLetter(char letter, char *str,char***newstr,int *numOfWords)
{
int i=0, count=0;
char *word;
char *delimiter = " ";
while (str[i] != '\0')
{
if (str[i]==letter ||str[i]==(letter-32 )) //if it founds the letter at the begining of the word, than run till the space//
{
while (str[i] != ' ' && str[i] != '\0' )
i++; //counting the number of words beginng with the letter given//
count++;
}
else
{
while (str[i] != ' ' && str[i] != '\0' )
i++;
}
}
*newstr = (char**)malloc (sizeof(char*)*count);
*numOfWords=count;
i=0;
word = strtok(str, delimiter); //we use strtok to separate each word from the origin string//
while(word!=NULL)
{
if (word[0]==letter ||word[0]==letter-32)
{
(*newstr)[i]=word; //insert the compatible words into the new 2D-string//
i++;
}
word = strtok(NULL, delimiter);
}
}
I call that function the by the following way:
#define _CRT_SECURE_NO_WARNINGS
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <conio.h>
#define SIZE 50
void Ex();
void wordsStartWithLetter(char letter, char *str,char***newstr,int *numOfWords) ;
void main()
{
Ex();
}
void Ex()
{
char ch;
char str[SIZE];
char **newstr;
int numOfWords,i;
printf("please enter a string: ");
_flushall();
gets(str);
printf("plese enter a letter: " );
_flushall();
ch=_getche();
wordsStartWithLetter(ch, str,&newstr,&numOfWords);
("the words of the origin string which start which %c :\n",ch);
for(i=0;i<numOfWords;i++)
printf("%s\n",newstr[i]);
for (i=0;i<numOfWords; i++)
free(newstr[i]);
free(newstr);
}

Answer 1

Consider this input string "a b" and assume the letter is c.
When i is 0 you enter the code below because str[0]is a which doesn't match the letter:
else
{
while (str[i] != ' ' && str[i] != '\0' )
i++; // Increment i from 0 to 1
}
In the above block, you increment i to 1 and then leave the block because str[1] is ' '
In the next main loop, you will again hit this code block:
else
{
while (str[i] != ' ' && str[i] != '\0' )
i++; // No increment, i.e. i stays at 1
}
but you will not increment i (as str[1] is a space). In other words - i remains at 1 and you have an infinite loop.
Maybe you can fix it by this:
else
{
while (str[i] != ' ' && str[i] != '\0' )
i++; // No increment, i.e. i stays at 1
// Add this line to remove the spaces
while (str[i] == ' ') i++;
}