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Searching for a keyword or value is the foundation of many computer programs. The most basic kind of search is a serial search.

Criteria are set up before the search begins. The search then starts with the first item and then moves to each item in turn, until either a match is found or it reaches the end of the data with no match found.

Example

Imagine that you have a database of sales made to customers. You need to deliver the goods that customer number 150 has bought, so need to find their address in the database.

The criterion is set first - Find the address for customer 150.

A serial search will begin at customer 1 and will search through each customer in turn until it reaches customer 150. It will then output the address for this customer. If it does not find customer 150, a message will be output to say that the customer is not found.

In pseudocode this would look like:

OUTPUT "Which customer number would you like to look up?"
INPUT user inputs customer number
STORE the user's input in the customer_number variable
counter = 0 
found = False
WHILE found = False and counter ≤ number_of_records:
	IF counter = customer_number THEN
		OUTPUT customer address
		found = True
    ELSE
	    add 1 to counter
    ENDIF
ENDWHILE
IF found = False THEN
    OUTPUT "Customer not found"
ENDIF

As a flowchart, this would look like: