Scanf not behaving as expected

Question

I am trying to use scanf() to input values to a structure using pointers.Can you help me to understand why my code is not working

This is my code:

#include<stdio.h>
struct student
{
   int no;
   float marks;
}st[2],*s;

main()
{
  printf("enter the values");
  for(s=st;s<st+2;s++)
  {
    scanf("%d%d",&s->no,&s->marks);
  }
  for(s=st;s<st+2;s++)
  {
    printff("%d\t%d\t",s->no,s->marks);
  }
}

in this code scanf is not working properly,it is taking only the first value

it's better to format your codes properly. – Raptor May 26 '15 at 06:27 — Raptor, May 26 '15 at 06:27
`main()` --> `int main(void)` – Sourav Ghosh May 26 '15 at 06:36 — Sourav Ghosh, May 26 '15 at 06:36
Voting to close as simple typo, wrong format specifier. – Lundin May 26 '15 at 06:45 — Lundin, May 26 '15 at 06:45

Spikatrix · Answer 1 · 2015-05-26T06:32:53.510

2

You are using the wrong format specifier. %d is used for ints while %f is used for floats. Use

scanf("%d%f",&s->no,&s->marks);

and

printf("%d\t%f\t",s->no,s->marks);

instead as s->marks is a float, not an int. Using the wrong format specifier leads to Undefined Behavior.

edited May 26 '15 at 06:32

answered May 26 '15 at 06:28

Spikatrix

20,225
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score 0 · Answer 2 · answered May 26 '15 at 06:34

 #include<stdio.h>
     struct student
       {
      int no;
      float marks;
         }st[2],*s;


 main()
  {
 printf("enter the values");
 for(s=st;s<st+2;s++)
  {
 scanf("%d%f",&s->no,&s->marks);
  }
 for(s=st;s<st+2;s++)
   {
  printf("%d\t%f\t",s->no,s->marks);
    }
   }

U have to use %f for float

score 0 · Answer 3 · edited May 26 '15 at 07:16

0

In the structure you have taken two variable one is int type and other is float type but while doing scanf(taking input) you are doing %d for float whereas it should be %f for float .This is a very minor mistake but you should try to avoid it on your own by just looking at your code carefully :)

Happy coding

edited May 26 '15 at 07:16

Gyapti Jain

4,056
20
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answered May 26 '15 at 06:52

Kunal Saini

138
10

`%f` is for double actually :) – Gyapti Jain May 26 '15 at 07:17
check this http://en.wikibooks.org/wiki/C%2B%2B_Programming/Code/Standard_C_Library/Functions/printf – Kunal Saini May 26 '15 at 07:50
Study about "default argument promotion rule of C", or [this question](http://stackoverflow.com/questions/4264127/correct-format-specifier-for-double-in-printf) – Gyapti Jain May 27 '15 at 13:12

Scanf not behaving as expected

3 Answers3