Putting data in files with for

Question

int main()
{
 FILE*arq;
 char a[500];
  int i,f;
  arq=fopen("test.txt","w+");
 for(i=0;i<5;i++){
  printf("Type the name:");
  fgets(a,500,stdin);
  fprintf(arq,"%s",a);
  printf("Enter the age");
  fscanf(arq,"%d", f);
  fprintf(arq, "%d", f);
 }
fclose(arq);
return 0;
}

I cannot put the name and age in the file because after typing the name it skips the typing of the age

Possible duplicate of [Simple C scanf does not work?](https://stackoverflow.com/questions/3744776/simple-c-scanf-does-not-work) — Mad Physicist, Jul 10 '18 at 04:54
@MadPhysicist I think fgets()+scanf(number) makes this different. The latter auto-ignores whitespace. doesn't it? — Yunnosch, Jul 10 '18 at 05:01
Given that they aren't passing a pointer to `fscanf()`, I'd wager that's their problem. — user1118321, Jul 10 '18 at 05:01
@user1118321. Or better yet, close as a typo. Literally just missing a single ampersand — Mad Physicist, Jul 10 '18 at 05:04
Missing an ampersand is not a typo next to a non-missing ampersand for an array, I disagree with that closing reason, too. — Yunnosch, Jul 10 '18 at 05:05

score 0 · Answer 1 · answered Jul 10 '18 at 05:05

You've failed to pass a pointer to the variable that will hold the result when calling fscanf(). It should be:

fscanf(arq, "%d", &f);

The & tells the compiler you want to pass in the address of f rather than the value of f. This is necessary because the last argument of fscanf is the address where you want the result stored.

score 0 · Answer 2 · answered Jul 10 '18 at 05:05

0

You need to give the address of the variable to be filled.

fscanf(arq,"%d", f);

->

fscanf(arq,"%d", &f);

For the first, reading a it is not necessary becaue it is an array, which gets treated as a pointer anyway.

answered Jul 10 '18 at 05:05

Yunnosch

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score 0 · Accepted Answer · answered Jul 10 '18 at 10:33

First of all, you have to give the address of the variable to be filled. Secondly, you are reading from the file, which is empty until you close it, so it won't wait from input from stdin. It should be like this:

fscanf(stdin,"%d", &f);

This will leave a '\n' in the buffer, which will be read by fgets. To prevent this, read the newline before the next iteration:

fgetc(stdin);

This code works for me:

int main()
{
 FILE*arq;
 char a[500];
 int i,f;
 arq=fopen("test.txt","w+");

 for(i=0;i<5;i++){
  printf("Type the name:");
  fgets(a,500,stdin);
  fprintf(arq,"%s",a);
  printf("Enter the age:");
  fscanf(stdin,"%d", &f);
  fprintf(arq, "%d", f);
  fgetc(stdin);
 }
 fclose(arq);
 return 0;
}

Putting data in files with for

3 Answers3