c - fprintf outputting ')' in txt file -

i have been trying create c program print current content of .txt file, allow user enter content wish there instead, , print content on previous txt file. resulting .txt file has ')' printed, replacing characters is printed.

#include <stdio.h> #include <stdlib.h> int main(void) {     file *filedisplay = fopen("password1.txt", "r" );     char c;      printf("current password is: ");      do{      c = fgetc(filedisplay);     printf("%c", c);      }      while (c != eof);     fclose(filedisplay);      char np[]="";      printf("\nplease enter new password: \n");     scanf(" %s", np);      file *file = fopen("password1.txt", "w" );     fprintf(file," %s", np);     fclose(file);     return 0; } 

for example, if user inputs

password

as char np, output fprintf is

p')'uord

the array np has room 1 character (the terminating '\0' of empty string "" initialize with), since not specify size it. can not fit string other empty string , rest of user's input overflows, causing undefined behaviour.

you need provide array large enough hold user's input (specify size between []) , should inform input function (here scanf, fgets might better here) of size knows not write past end of array.