io - Segmentation Fault when writing to a file in C -

whenever attempt write file, getting segmentation fault. don't have access software can tell me it's coming since i'm @ school. if me out great.

//olmhash.c  #include <stdio.h> #include <stdlib.h> #include <string.h> #include "olmhash.h"  int main() {     createaccount();     return 0; }  struct account createaccount() {       struct account *newaccount;     newaccount = (struct account *)malloc(sizeof(struct account));      printf("enter userid: ");     scanf("%s", newaccount->userid);     printf("\nenter password: ");     scanf("%s", newaccount->password);      char *output = malloc(sizeof(char) * 255);     strcpy(output, newaccount->userid);     strcat(output, "\t");     strcat(output, newaccount->password);      file* fp;     fp = fopen("accountslist.txt", "r");     fputs(newaccount->userid, fp);      free(output); } 

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//olmhash.h  struct account {     char userid[32];     char password[12];    };  struct account createaccount(); 

you opened file reading instead of writing, , did not check action succeeded. try

fp = fopen("accountslist.txt", "w"); if(fp == null) {     // out code     exit(1); }