Python- Finding the largest number in a list using forloop or while loop

Question

Basically we are given a list of numbers and we are asked to write an algorithm to find the largest number in the list, note: the numbers are not in order and may contain decimals and negative numbers. this must be done using loop statements in python 3.2.3 Thanks.

alist=[3,10,90,5,-2,4,18,45,100,1,6]
largest=int()
for large in alist:
    if large >= large+1:
       largest=large
print(largest)

do you want someone to do your homework? what have you done? — user1406062
– user1406062, Commented Oct 7, 2012 at 4:24
not a homework question lol, im curious as to whats the simplest way to go about this. new to programming here...the teacher showed it in a complicated way in class and i didnt get it :S — 3MIN3M
– 3MIN3M, Commented Oct 7, 2012 at 4:26
You have several problems with your code. 1) int() returns 0, so if you have a list of negative numbers then your code would print 0 instead of the largest number. 2) large will never be > or = to large+1 so largest will never change and your code will print 0 every time. You should set largest equal to the first element in the list like I did in my answer. you should be comparing large to largest instead of large+1. Then your code will work. — alanmanderson
– alanmanderson, Commented Oct 7, 2012 at 7:18
Does this answer your question? Find the greatest number in a list of numbers — Karl Knechtel
– Karl Knechtel, Commented Mar 8, 2023 at 16:21

Sheena · Accepted Answer · 2012-10-07 20:47:06Z

3

there's also a built in function called max... works like a charm

answered Oct 7, 2012 at 20:47

Sheena

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2 Comments

alanmanderson Over a year ago

He said he was asked to write an algorithm so he could learn Programming.

3MIN3M Over a year ago

"must be done using loop statements in python 3.2.3" :) also how do you close a question? lock it perhaps? just wondering

Amirmohammad Divani · Accepted Answer · 2022-04-26 08:07:35Z

This question was asked 9 years ago but I'm giving my answer because the question is still relevant today

we can do this for both numbers and strings

A) Finding the largest number in a given list:

your_list = [54, 26, 29, 48, 56, 32, 15, 17]
largest_num = -99999999 # Any value below zero is ok if you know there 
                        # are larger numbers in the list
    
for i in your_list:     # Checking every item in the list
    print("current number:", i) # Printing every item in the list 
                                # regardless of their value
    if i > largest_num: # Is it larger than -99999999?!
        largest_num = i # then value of largest number should be equal 
                        # to the value of i(as integer) 
print("largest number:",largest_num) # Let's print the result when 
                                     #  we're done

B) Finding the largest string in a given list:

my_list = ["a", "b", "c", "A", "B", "C", " "]
largest_str = my_list[0]
for i in my_list:
    print("current str:", i)
    if i > largest_str:
        largest_str = i

print("largest_str:", largest_str)

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