How do you find the largest of three numbers in Python without max()?

Use if-elif-else: if a is greater than both b and c, a is the largest; otherwise compare b with c. That is the program at the top of this page.

What happens if two of the numbers are equal?

The program still prints the right value. With 5, 5 and 3 the first condition is false, b > c is true, and it prints 5.

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Largest of Three Numbers in Python

easyif / elsePython

A favourite practical question because it tests whether you can build a decision with more than two branches.

Quick answer

Use if-elif-else: if a > b and a > c, a is the largest; elif b > c, b is the largest; otherwise c is. The one-line way is max(a, b, c). For 67, 19 and 34 the largest is 67.

The question

Read three different integers (one per line) and print the largest of them. Use if/elif/else — do not use max().

The code

program.py

a = int(input())
b = int(input())
c = int(input())
if a > b and a > c:
    largest = a
elif b > c:
    largest = b
else:
    largest = c
print("Largest =", largest)

Try it Yourself »

Input

67
19
34

Output

Largest = 67

How it works

1First check whether a is bigger than both b and c — the and operator needs both comparisons to be true.
2If a is not the largest, the answer must be b or c, so a single comparison b > c decides it.
3Store the winner in largest and print it once at the end.

Which branch runs for 67, 19 and 34?

Check	With the values	Result
a > b and a > c	67 > 19 and 67 > 34	True → largest = 67
elif b > c	not checked	—
else	not reached	—

Only the first true branch runs, so the program prints Largest = 67.

Common mistakes

Writing if a > b > c — it only proves a > b and b > c, and misses the case where c > b.
Using max() when the question says to use if-else — examiners take marks for that.

Largest of three numbers using max()

The shortest way. Use it when the question does not insist on if-else — max() accepts any number of values.

program.py

a = int(input())
b = int(input())
c = int(input())
print("Largest =", max(a, b, c))

Try it Yourself »

Input

12
45
7

Output

Largest = 45

Largest of three numbers using nested if

First decide between a and b, then compare the winner with c. Some question papers ask for this form by name.

program.py

a = int(input())
b = int(input())
c = int(input())
if a > b:
    if a > c:
        largest = a
    else:
        largest = c
else:
    if b > c:
        largest = b
    else:
        largest = c
print("Largest =", largest)

Try it Yourself »

Input

7
88
23

Output

Largest = 88

Questions students ask

How do you find the largest of three numbers in Python without max()?: Use if-elif-else: if a is greater than both b and c, a is the largest; otherwise compare b with c. That is the program at the top of this page.
What happens if two of the numbers are equal?: The program still prints the right value. With 5, 5 and 3 the first condition is false, b > c is true, and it prints 5.

Now solve a similar question yourself

A new Python question every time, checked instantly.

Practice questions

Preparing for NIELIT O Level?

This program is the kind asked in the M3 (Python) theory paper and the PR-3 practical exam.

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