unable to input character array in c++

Question

Code:

#include<iostream>
#include<stdio.h>
#include<string.h>

using namespace std;

struct student
{
    char name[20];
    int id;
    float cgpa;
};

int main()
{   
    student s[100];

    int n,i;
    cout<<"Enter number of students: ";
    cin>>n;
    cout<<"Enter records of "<<n<<" students"<<endl;

    for(i=0; i<n ; i++)
    {   
        cout<<"Enter name: ";           
        gets(s[i].name);
        cout<<"Enter ID: ";
        cin>>s[i].id;
        cout<<"Enter CGPA: ";
        cin>>s[i].cgpa;
        cout<<endl;
    }   

    for(i=0; i<n ; i++)
    {
        cout<<"\nName: "<<s[i].name;
        cout<<"\nID: "<<s[i].id;
        cout<<"\nCGPA: "<<s[i].cgpa<<endl;
    }   
}

output:

Enter number of students: 2
Enter records of 2 students

Enter name: Enter ID:

using sublime text 3 c++

There are quite a lot of problems in your code. The biggest is that you don't use C++ functions to read all input into C++ strings, but instead `char` arrays and the [***dangerous***](https://stackoverflow.com/questions/1694036/why-is-the-gets-function-so-dangerous-that-it-should-not-be-used) (and no longer standard C or C++) function `gets`. I suggest you get [a few good C++ books to read](https://stackoverflow.com/questions/388242/the-definitive-c-book-guide-and-list/388282#388282) and almost start over from the beginning. — Some programmer dude, Oct 25 '18 at 06:31
As for your problem: You ended the last input (the number `2`) with the `Enter` key, right? That `Enter` key will be put into the input buffer as a newline `'\n'`. Now think about what happens when you call `gets` and the first character it reads is the newline. — Some programmer dude, Oct 25 '18 at 06:35
@some programmer dude if i add fflush(stdin) before gets, even then it doesn't work. I'm supposed to use these commands as instructed by our teacher. He's teaching using codeblocks. — Aman Yadav, Oct 25 '18 at 06:51
And that is explicitly mentioned in the standards as *undefined behavior*. Passing an input-only stream to `fflush` is not supported in the standards, but some systems implement it as an *extension*. Don't do it though. And really, stop using `char` arrays and most importantly stop using `gets`. — Some programmer dude, Oct 25 '18 at 06:54

score 1 · Accepted Answer · answered Oct 25 '18 at 06:37

1

Use <string> for name instead of a character array, then use the cin as usual, instead of gets, to read in the string.

answered Oct 25 '18 at 06:37

awiebe

3,758
4
22
33

score 0 · Answer 2 · answered Oct 25 '18 at 06:57

As pointer out by Some Programmer Dude, the enter you pressed is put into the input buffer as a newline '\n' and then later accepted by get() causing it to skip to the next input.

There are two ways you can approach this problem :

Use cin.ignore() at the start of the loop where you take the input.
The better choice will be to get rid of gets(). It has been deprecated since c++14. Secondly, replace the character array with a string.

So the structure would see a modification string name;

And simply do cin>>s[i].name; in the loop.

Thats it.

Also, its preferable to use cstdio instead of stdio.h.

Happy to help, and welcome to Stack Overflow. If this answer or any other one solved your issue, please mark it as accepted. — arjunkhera, Oct 25 '18 at 07:26

unable to input character array in c++

2 Answers2