Input by using gets function

Question

In Below Code When I want to Enter Record of second student or >2 student .. Compiler skip Name Input and take Input for class and age .. What a problem please help me ?

#include <stdio.h>
#include <conio.h>

struct Student
{

char Name[16];
char Class[16];
int age ;

};

void main()

{

struct Student a[5] ;

for(int i=0 ; i<5 ; i++)
{
printf("\n Enter Name  :");
gets(a[i].Name);
printf("\n Enter Class :");
gets(a[i].Class);
printf("\n Enter Age   : ");
scanf("%d" , & a[i].age);
}

getch();
}

cnicutar · Accepted Answer · 2012-02-03T19:23:55.803

3

The problem is common enough. Try this:

scanf("%d ", &a[i].age);
         ^ <--- This space will make scanf eat the remaining blanks

There are C FAQs about this:

Secondary notes:

Don't use gets. Use fgets instead.

edited Feb 03 '12 at 19:23

answered Feb 03 '12 at 19:18

cnicutar

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The note **don't use `gets`** is *very important*. And `gets` is deprecated, and removed (or deprecated) in recent C or Posix standards – Basile Starynkevitch Feb 03 '12 at 19:26
how to get input by fgets in above case ? – Muhammad Faisal Feb 03 '12 at 19:35
1

@MUHAMMADFaysal Look in the manual. If I just tell you it won't teach you anything. – cnicutar Feb 03 '12 at 19:38

score 3 · Answer 2 · edited Nov 19 '17 at 19:25

First off, never use gets. There is no way to tell it how big your buffer is, so it will cheerfully write input past the end and make the program blow up. This used to be the number one cause of remotely exploitable security holes in network servers.

Second off, never use any of the *scanf functions either, because:

Some scanf format strings are just as unsafe as gets, notably %s with no size modifiers.
Numeric overflow inside scanf provokes undefined behavior, which means your program may crash simply because someone typed a number that was too big.
It is extremely difficult to write a robust input parser using scanf, because if it fails, it does not tell you precisely where the problem characters were.

For a simple task like this one, you should use fgets (or, better, getline if you have it) and convert the age to an integer with strtoul. (Age cannot be negative, so you want the unsigned version. Don't use atoi and friends - just like *scanf, they don't give you enough information about invalid input.)

For more complicated tasks, you should reach for lex and yacc.

score 1 · Answer 3 · answered Feb 03 '12 at 19:23

It's the scanf. When you press ENTER after it, the newline completes the next call to gets.

To fix this, you can add a getchar at the end of the loop, after the scanf, which will consume the newline.

for(int i=0 ; i<5 ; i++)
{
    printf("\n Enter Name  :");
    gets(a[i].Name);
    printf("\n Enter Class :");
    gets(a[i].Class);
    printf("\n Enter Age   : ");
    scanf("%d" , & a[i].age);
    getchar();
}

Input by using gets function

3 Answers3

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