General Algorithm

A result of -1 is used to indicate “not found”.

found = -1
for each item in list
    if item = target value then
        found = index value
    end if
next item

Find if a value is in a list

#
target = "fred"
  
found = False
for name in names: 
    if name == target: 
        found = True
        break # can stop searching
  
if found: 
    print(f"{target} was found"}
else: 
    print(f"{target} was not found"}
#

Find location of a value in a list

#
target = "fred"
  
found = -1
for name in range(20):
    if names[name] == target:
        found = name
        break # can stop searching
  
if found == -1:
    print(f"{target} was not in list"}
else:
    print(f"{names[found]} had a mark of {mark[found]}")
#