Thread: Some Problem With My Program

Problem: I created a program for booking tickets. It works fine when its for single user. But when i make it for multi user, "user[100]". Funny characters starts to pop up when i key in the seats numbers. Example Smiling face, heart shape etc. When i open the source file user.txt those funny characters is printed as C in the file. Causing my program to be very unstable. Below is my code for booking.
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Code:

int choice();
int i,m,n,row,column,x=5,y=5;

#define FILENAME "user.txt"

void show_main_menu();
void logo();
void book_ticket();
void edit_booking();
void cancel_booking();
void view_available();
void exitt();
void thank_you();
void look_up();

struct data
{
    char useless[1];
    char seat[5][10];
    char name[30];
    char nirc_number[10];
    char contact_number[10];
}user[100], data, sales_data[100], temp;

Code:

/*#############################################################################*/
/*                                Book Ticket Function                         */
/*#############################################################################*/
void book_ticket()
{					 
    
    FILE *fptr;
    int quit=1;
    textcolor(YELLOW);
    fptr=fopen("user.txt","r");
    fread(&user[100],sizeof(user[100]),1,fptr);
    fclose(fptr);
    while(column!=99)   
    {
                system("cls");
                user[100].seat[row-1][column-1]='X';
                
                printf("\t\t\t \t      SCREEN           \n\n");
                printf("\t\t             1  2  3  4  5  6  7  8  9  10\n");
                
                printf("\n\t\t\t1   ");        
                for(i=0;i<10;i++)
                {
                    if(user[100].seat[0][i]>0)
                    printf(" %c ",user[100].seat[0][i]);
                }
                printf("\n\n");
                
                printf("\t\t\t2   ");
                for(i=0;i<10;i++)
                {if(user[100].seat[0][i]>0)
                    printf(" %c ",user[100].seat[1][i]);
                }
                printf("\n\n");
              
                printf("\t\t\t3   ");
                for(i=0;i<10;i++)
                {if(user[100].seat[0][i]>0)
                    printf(" %c ",user[100].seat[2][i]);
                }
                printf("\n\n");
                
                printf("\t\t\t4   ");
                for(i=0;i<10;i++)
                {if(user[100].seat[0][i]>0)
                    printf(" %c ",user[100].seat[3][i]);
                }
                printf("\n\n");
               
                printf("\t\t\t5   ");
                for(i=0;i<10;i++)
                {if(user[100].seat[0][i]>0)
                    printf(" %c ",user[100].seat[4][i]);
                }
                
                printf("\n\n\n\n\n");
                printf("\t\t\t   Enter Row Column(99,99 to quit): "); //choose to for 'X'  
                scanf("%d,%d",&row, &column);     
                if(row==99)
                        break;                  
    }
    clrscr();
    logo();
	printf("\n\n\n\n\t");
	gets(user[100].useless);
    printf("\n\tPlease Enter Your Name:");
	gets(user[100].name);
	printf("\n\tPlease Enter Owner IC Number:");
	gets(user[100].nirc_number);
	printf("\n\tPlease Enter Your Contact Number:");
	gets(user[100].contact_number);
	fopen("user.txt", "ab+");
    fwrite(&user[100],sizeof(user[100]),1,fptr);
    fclose(fptr);    
	printf("\n\n\n\n");
	printf("\n\tThank You For Providing Your Details");
	printf("\n\tPress Anykey To Continue");
	getch();
    thank_you();       
}

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If i was to change the "user[100]" to "user" it works fine. But i need it to be multi users. I have totally no idea how i can solve this problem. Appreciate help from members in this forum.
Can upload my whole program too if necessary. Heres the screenshot.
http://www.geocities.com/eradicate85/Program.JPG