segmentation fault

[C-learning]

Hello!

I written a procedure that is supposed to only include one blank
where there are more thatn one space.
Example "A' ' ' 'D' ' 'E' 'FG' 'R' 'G' ' 'T"
should be "A D E FG R G T"
(' ' stands for space )
It works in turbo c but not in linux
I get segmentation fault all the time.
What have i done wrong


Here is the code

char *noDoublespace(char str[]){
	int flag_isspace=0;
	int i=0,y=0;
	while(str[i]){
		if(str[i]==' ' && !flag_isspace){
			flag_isspace=1;
			str[y]=str[i];
			y++;
		}
		else if(str[i]!=' '){
			flag_isspace=0;
			str[y]=str[i];
			y++;
		}
	i++;
	}
	str[y]='\0';
}

[C-learning]

I do it the second way.
like this

noDoublespace(str);

printf("%s\n",str);

and have declared char *str="somethin...";

[C-learning]

Ok, thanks for the help.
Now i see the big picture.