can anyone help me to detect error if the programme of hotel managemaent

Code:

#include<stdio.h>
#include<string.h>
#include<stdlib.h>
void checkin();
void checkout();
void records();
void calc();
struct customer
{
 int room_id;
 char f_name[20];
 char l_name[20];
 char nationality[20];
 int advance;
 struct list *next;

};struct customer new1[100];
 *start;

struct date
{
int day;
int month;
int year;
};struct date doe[2];

  main()
  {
	int menu;
	start=NULL;

	{
 printf("1.room details\n2.check In\n3.Check out\n4.Edit\n5.Report\n6.Exit\nEnter your choice");
  scanf("%d",&menu);
  }

  if (menu==1)



void checkin()
{
printf("Category:\nSS-&gt;Single Suite:\nSR-&gt;Single Room:\nDS-&gt;Double Suit:\nDR-&gt;Double Room:\n");
char category[4];
printf("select the category of room: \n");
gets(category);

	  puts("Enter the details of the customer:\nRoom alloted...");
	  gets(new1[i].room_id);
	  for(i=0;i&lt;=99;i++)
	  puts("Enter the first name of the customer:");
	  gets(new1[i].f_name);
	  for(i=0;i&lt;=99;i++)
	  puts("Enter the last name of the customer:");
	  gets(new1[i].l_name);
	  for(i=0;i&lt;=99;i++)
	  puts("Enter the nationality of the customer:");
	  gets(new1[i].nationality);
	  for(i=0;i&lt;=99;i++)
	  puts("Enter the date of entry of the customer in the form dd/mm/yyyy:");
	  scanf("%d%*c%d%*c%d",&doe.day,&doe.month,&doe.year);

		puts("Enter the amount of the advance paid by the customer:");
	  gets(&new1[i].advance);
	  for(i=0;i&lt;=99;i++)
}
 void checkout()
 {
 printf("enter the date of check out in the form dd/mm/yyyy:\n");
 scanf("%d%*c%d%*c%d", &doe.day,&doe.month,&doe.year);
  /*bill calculator*/

 void calc();/*function call*/
 }
 void calc()/*function defination*/
{
int func1(int x);
void main()
{

int day1,mon1,year1,day2,mon2,year2;
int ref,dd1,dd2,i;
printf("Enter first day, month, year");
scanf("%d%d%d",&day1,&mon1,&year1);
scanf("%d%d%d",&day2,&mon2,&year2);
ref = year1;
if(year2&lt;year1)&gt;
ref = year2;
dd1=0;
dd1=func1(mon1);
for(i=ref;i&lt;year1;i++)&gt;
{
	if(i%4==0)
	dd1+=1;
}
dd1=dd1+day1+(year1-ref)*365;
printf("No. of days of first date fronm the Jan 1 %d= %d",year1,dd1);
/* Count for additional days due to leap years*/
dd2=0;
for(i=ref;i&lt;year2;i++)&gt;
{
	if(i%4==0)
	dd2+=1;
}
dd2=func1(mon2)+dd2+day2+((year2-ref)*365);
printf("No. of days from the reference year's first Jan = %d",dd2);
printf("Therefore, diff between the two dates is %d",abs(dd2-dd1));

}




int func1(x)       //x for month y for dd
{  int y=0;
switch(x)
{
case 1: y=0; break;
case 2: y=31; break;
case 3: y=59; break;
case 4: y=90; break;
case 5: y=120;break;
case 6: y=151; break;
case 7: y=181; break;
case 8: y=212; break;
case 9: y=243; break;
case 10:y=273; break;
case 11:y=304; break;
case 12:y=334; break;
default: printf("Error encountered");
}
return(y);
} /*bill opens in a file*/
  {
FILE *fp;
char ch;
fp=fopen("qqq.c","r");
while(1)
{
ch=fgetc(fp);
if(ch==EOF)
break;
printf("%c",ch);
}
printf("\n");
fclose(fp);
return 0;
}



















printf("enter the room id which is to be emptied:");
free(void,**************)

 }
void records()
printf("1.Show room records\n");
printf("2.show customer records\n");
scanf("%d",)
}

 

In standard C, you need to declare variables at the start of a code block.

Code:

puts("...");
char item[4];

stuff like that won't compile in standard C; however, I believe it will if compiled as cpp.

Code:

struct customer
{
int room_id;
char f_name[20];
char l_name[20];
char nationality[20];
int advance;
struct list *next;

};struct customer new1[100];
*start;

struct customer *next; is *probably* what you're after

if you use code tags and formatted source, it will be easier to see what other things may be problematic.