Odd C error: Adding a print statement before a line makes it run, but it errors without it -

i'm writing basic tokenizer practice c, running odd error. doing wrong?

this crashes:

char* maketoken(char* string, char deliminator) {    char* token;    char* counter=token;    char currentchar;    string-=1;    while((currentchar=*(string+=1))!=deliminator)    {     *counter=currentchar;     counter++;    }     *counter='\0';     return token; } 

but runs fine:

char* maketoken(char* string, char deliminator) {    char* token;    char* counter=token;    char currentchar;    string-=1;    while((currentchar=*(string+=1))!=deliminator)    {     printf("making token\n");     *counter=currentchar;     counter++;    }     *counter='\0';     return token; } 

both versions give error on machine. because of no garbage collection in c, second version seems work on machine.

there several problems code here's working version

char* maketoken(char* string, char delimiter) {    //you need initialize token    char* token=malloc(strlen(string)); // token can long string    char* counter=token;    char currentchar=*string;    if(token==null){       return null;    }     //if delimiter not exist loop must end    while(currentchar!=delimiter&&currentchar!='\0')    {     *counter=currentchar;     counter++;     string++;     currentchar=*string;    }    *counter='\0';    return token; }