person.txtCode:#include <stdio.h> #include <stdlib.h> struct data { int id; char name[30]; int number; int grade; }; int main(void) { FILE *fp; struct data person; fp = fopen("person.txt", "r"); if (fp = NULL) exit(1); fread(&person, sizeof(data), 1, fp); fclose(fp); printf("%s\n", person.name); return 0; }
When I run this program, the send report window pops up and my program closes. What am I doing wrong? Thanks.Code:365523 Max Payne 28 82
Well for starters, it should be:This isn't C++ you know. Unless of course you're compiling incorrectly. Next, you don't have a null on the end of your "string". Oh, and you're probably reading more than your file contains, since this is after all a text file, and you're treating it as a binary fields.Code:fread(&person, sizeof(struct data), 1, fp);
Quzah.
Hope is the first step on the road to disappointment.
you have some minor mistakes like
[CODE]
if (fp=NULL) //it should be
if (fp==NULL)//notice the double = symbols
[\CODE]
Also I believe that the structure you declare named person of type data should be really a pointer to a structure struct data *person
try it that way
what must be happening is that the pointer is trying to acces somewhere in the memory where you should not acces, so it crashes and exis th program because windows is protecting itself
sorry, no *person required, its only the double == what is missing
Hum, that was silly of me
My output:Code:#include <stdio.h> #include <stdlib.h> struct data { int id; char name[30]; int number; int grade; }; int main(void) { FILE *fp; struct data person; fp = fopen("person.txt", "r"); if (fp == NULL) exit(1); fread(&person, sizeof(data), 1, fp); fclose(fp); printf("%s\n", person.name); return 0; }
Why do I get that extra character after the number 82? Thanks.Code:23 Max Payne 28 82↕
If the input is really a text file, then fread() is the wrong thing to be doing - it's not going to convert a string "82" into an integer value 82 for you.
Also, you have only one printf line, and 4 lines of output - are you really pasting the code you're running?
If you dance barefoot on the broken glass of undefined behaviour, you've got to expect the occasional cut.
If at first you don't succeed, try writing your phone number on the exam paper.
Probably. They've probably got it all stuck in the name string, since they're just reading as text, because the entire output fits in the space alotted for 'name'. I'm just surprised it stops there. But no one listens to me any more.
Quzah.
Hope is the first step on the road to disappointment.
Or you can just do:Originally Posted by louis_mine
since NULL will evaluate to false...Code:if(fp)
