Scanf函数不接受输入

Question

I am working on a simple C program using a struct named 'student'. Here is my code

#include<stdio.h>
#include<stdlib.h>
  struct  student {
    char name[50];
    int id;
    float marks_1;
    float marks_2;

};


void main(){

    int num,a,i;
    printf("Enter number of students\n");
    scanf("%d",&num);
    struct student s[num];
    for(i=0;i<num;i++)
    {
        a=i+1;
        printf("Enter name of student number %d\n",a);
        scanf("%[^\n]%*c",s[i].name);

    }

  }

When I run the program I am able to enter the number of students correctly, but after that I am not able to enter the name corresponding to each student. This is the output that I get.

Enter number of students
2
Enter name of student number 1
Enter name of student number 2

RUN FINISHED; exit value 2; real time: 1s; user: 0ms; system: 0ms

What might be the problem? Any help appreciated

Answer 1

scanf("%d",&num);

leaves the newline you typed to send the input to the programme in the input buffer. Thus the first iteration of

for(i=0;i<num;i++)
{
    a=i+1;
    printf("Enter name of student number %d\n",a);
    scanf("%[^\n]%*c",s[i].name);

}

immediately finds that newline and scans in an empty string.

Consume the newline before scanning, either by changing the first format to "%d%*c" or by adding a space to the start of the name-scanning format to skip initial white space.

Answer 2

change scanf("%[^\\n]%*c",s[i].name); to scanf(" %[^\\n]%*c",s[i].name); . Notice the space given before specifier to consume last input char left in stdin.

Answer 3

Scanf function not accepting input

If scanf() doesn't work, then use fgets() :

fgets(s[i].name, sizeof(s[i].name), stdin);

And stay far away from scanf() if/while you don't have a full, proper understanding of how it works, because it's not intuitive to use, so to say. (It's also unsafe if you are not careful enough, and in this case, you weren't. The code is prone to buffer overflows.)

Answer 4

I'm not sure what you're trying to do here:

scanf("%[^\n]%*c",s[i].name);

but try replacing it with:

scanf("%50[^\n]s",s[i].name);

Answer 5

to read a line in c that include white spaces use fgets (name, 100, stdin);

here is the full code:

#include<stdio.h>
#include<stdlib.h>
  struct  student {
    char name[50];
    int id;
    float marks_1;
    float marks_2;

};


void main(){

    int num,a,i;
    printf("Enter number of students\n");
    scanf("%d",&num);
    struct student s[num];
    for(i=0;i<num;i++)
    {
        a=i+1;
        printf("Enter name of student number %d\n",a);
        fgets (s[i].name, 50, stdin);

    }

  }

scanf will read until the first whitespace, but not fgets , however, if you'll press enter when using fgets it'll will be stored in the string as well. so you need to remove it afterwards