Unexpected Output plus segmentation error with my C program

I am trying to learn programming and was trying the following code in C. However, As you can see below I am not getting the expected output and I am getting a segmentation error while trying out solutions :

I feel I am doing something wrong with the declaration of First name or something. But not able to figure it out.

My Code:

#include <stdio.h>

int main(void){
    char first_name;
    printf("Enter your name: \n");
    scanf("%c", &first_name);
    printf("Hello, %c", first_name);
}

Actual Output

This is the output I am currently getting:

Enter your name: 
asdasfasf
Hello, a

Expected Output

Enter your name: 
asdasfasf
Hello, asdasfasf

>Solution :

Here is my answer

#include <stdio.h>

int main(void){    
        char first_name[100] = {0}; 
        printf("Enter your name:(Max length is 99)\n"); 
        scanf("%99s", first_name); 
        printf("Hello, %s\n", first_name); 
}

Run it will output

Enter your name:(Max length is 99)
asdasfasf
Hello, asdasfasf