A question on Binary Search

general
,
1

I compiled the following code:

#include<stdio.h>
int main()
{
  int i,j,n;
  char str[20][20],temp[20];
  clrscr();
  puts("Enter the no. of string(s) to be sorted");
  scanf("%d",&n);
  for(i=0;i<=n;i++)
      gets(str[i]);
  for(i=0;i<=n;i++)
      for(j=i+1;j<=n;j++)
      {
	   if(strcmp(str[i],str[j])>0)
	   {
	       strcpy(temp,str[i]);
	      strcpy(str[i],str[j]);
	      strcpy(str[j],temp);
	   }
      }
  printf("The sorted list:\n");
  for(i=0;i<=n;i++)
      puts(str[i]);
      getch();
  return 0;
}

The question is to apply binary search to find the location of string (to be taken as an input from the keyboard). How should I do that?
Please help.

2

Please, put your code in proper blocks using indentation. It’s really tough to even read it!! No offence please, or you may like posting the ideone code.

3

Sort the array in which you have stored the strings and then use this:

// declarations like: char str[num+][100] : array for storing strings
// a: string to be searched
int low=0,high=num-1,pos=-1;
while(low<=high)
{
	int mid = (low+high)/2;
	
	if(strcmp(str[mid],a)==0)
	{
		pos=mid;
		break;
	}
	else if(strcmp(str[mid],a) <0)// if the string at the middle is less than what we are searching
	low=mid+1;
	else
	high=mid-1;  // middle string is greater, our string will be in left half
}