A peculiar bug while reading and printing strings of *char in C -

i've encountered odd. string of char (let's call word) turns out have additional letters when print it.
contatenated letter varies depending on:

1. the length of proper prefix word.
2. the number of spaces after word.

i'm parsing word line 1 line form standard input. i'm using function readword word out of line:

void readword(char **linepointer, char **wordpointer){   char *line  = *linepointer;   char *word = *wordpointer;   while (!isendofline(line) && islowercaseletter(*line)){     *word = *line;     word++;     line++;   }   word++;   *word = '\0';   printf("the retrieved word is: %s.\n", *wordpointer)   *linepointer = line; } 

my inputs/outputs (please note call readword function after taking care of insert , whitespace between):

// input 1 : insert foo insert ba      // several spaces after 'ba' // output 2: retrieved word foo. retrieved word bas.  // input 1 : insert foo insert ba      // several spaces after 'bar' // output 2: retrieved word foo. retrieved word bare. 

i thinking whether allocate *word , guess do:

root.word = (char *)malloc(sizeof(char *)); //root structure 

moreover, unlikely connected errors of reassigning word string because clear @ beginning of readword() function.

thank help. indeed challenging bug me , don't know else can do.

update

it turns out have problems allocating/reassigning, since:

//input insert foo//no spaces   insert bar                //spaces here //output word variable before calling readword function: ' '. retrieved word foo. word variable before calling readword function: 'insert foo '. retrieved word bare. 

never trust input, check spaces go beginning of word.

you increment word 1 many, @rpattiso notes.

i have doubts memory allocation (you don't show code): root.word = (char *)malloc(sizeof(char *)); allocates room pointer char, not allocate room characters themselves. readword can that.

the following adapted version should work (updated):

void readword(char **linepointer, char **wordpointer){     char *line  = *linepointer;     int i;      while (!isendofline(line) && !islowercaseletter(*line)) line++; // go begin of word     *linepointer= line;     while (!isendofline(line) &&  islowercaseletter(*line)) line++; // go end of word      i= line - *linepointer;                     // allocate room word , copy     *wordpointer= malloc((i+1) * sizeof(char));     strncpy(*wordpointer, *linepointer, i);     (*wordpointer)[i]= '\0;      printf("the retrieved word is: %s.\n", *wordpointer);     *linepointer = line; }