Thread: What is sequential search?

Sequential search is simply iterating through the items, one by one, until the search ends. In the for loop, the variable i, starts at 0, and stops when either the value of i is no longer less than 7, or if nums[i] == 11. Note that index is one less than the values that the array[i] is given, in this program.

Code:

int nums[7] = {1, 2, 3, 4, 5, 6, 7};
int i  = 0;
int used = 7;

for(i = 0; i < used; i++){
     if(nums[i] == 11)
          break;
}

if(used >= 7)
     printf(“Item not found”);
else
     printf(“Item found - %d “, nums[i]);<-----Add ;

1. Proper indentation cannot be stressed enough. You should always indent dependent lines of code, it will help you to find potential errors.
2. The first if statement will always evaluate to true in your code (see what is in red). Perhaps the if statement was suppose to be:

Code:

if( i >= used)
     printf.....

3. Going along with #2, avoid using "magic numbers". Having number literals in code with no rhyme or reason is one of the easiest ways to make code hard to maintain, update, and troubleshoot.
4. You are missing a semicolon on your final statement.

Adak answered how a sequential search worked, to answer your question:

Originally Posted by Haakon

Could someone tell me how and why this method works?

....it doesn't.

Originally Posted by AndrewHunter

....it doesn't.

Rather, the implementation of sequential search that you posted does not work. (Although it coincidentally gives the correct answer in this case, assuming that the missing semi-colon is added in, and you fix those weird double quotes that aren't.)

That wasn't my implementation Laser, it was the OP. I was using the red highlighting to point out what was wrong, which I pointed out in statement 2.

Originally Posted by AndrewHunter

That wasn't my implementation Laser, it was the OP. I was using the red highlighting to point out what was wrong, which I pointed out in statement 2.

Obviously "you" refers to Haakon
It might not even be Haakon's implementation (e.g., it could have been a mistake in the teacher's example), which is why I stated that it was "the implementation of sequential search that you posted".

Originally Posted by laserlight

Obviously "you" refers to Haakon
It might not even be Haakon's implementation (e.g., it could have been a mistake in the teacher's example), which is why I stated that it was "the implementation of sequential search that you posted".

My bad Laser. I see what you (meaning you) were saying now.

Code:

#include<stdio.h>

  int sequential_search(char *items, int count, char key)
  {
    register int t;

    for(t=0; t < count; ++t)
      if(key == items[t]) return t;
    return -1; /* no match */
  }

  int main(void){
     char *str = "asdf";
    
     int index = sequential_search(str, 4, 's');
    
     printf("%d",index);
 
  }

Thank you for posting something that really had nothing to do with the topic at hand with the exception of that it is a sequential search. Also....

Register keyword....really? Although it is 'cute' and I love putting random keywords into my programs to 'spice things up', it is not needed here and it is important to note that the compiler will just ignore you and put the variable where it wants to anyway.

Although since you like keywords, may I suggest the real interesting return statement......Implicit integer returns in main are deprecated; you need to positively return a value to the OS.

Mallory: I have removed your link because it is just advertisement. In the future, place such personal links in your signature instead. If you do not yet have the permission to set a signature, hang around first and contribute sensibly, then such an option will become available to you.

Originally Posted by AndrewHunter

Implicit integer returns in main are deprecated

That is not true.

Originally Posted by Haakon

So I understand the point of sequential search now, however with the task I've given I'm not sure if my code still is sequential search.. Yes or no?

No, it needs to be a search before it can be an sequential search.

You have to initialize the array before you can/should search it. I would mark off for this; I would bet you are supposed to write a search function not a comparison test. Edit: Technically it might count as a search; but, I would not think most graders will agree.

See Mallory post for a search function example.

Edit: My post assumes you have learned to write functions; if you have not, then the assignment (as described by you) makes little sense.

Edit: If you declare a array "int fives[10]" then you CAN NOT access "fives[10]" because the good indexes go from 0 to 9.
You code will do that because you use " i<=used" in the for loop.

Edit: It is good programming to avoid the use of "magic constants" or "magic numbers"; this is done to make the code easier to understand and modify.
http://en.wikipedia.org/wiki/Magic_n...ical_constants
Note: I would ignore this issue (magic constants) for now; but, realize some graders might mark off for using them.

Tim S.

Still confused by what a sequential search is? If you read this far, you used a sequential search of the posts in this thread to arrive here.


Quzah.