How to Find Output of Python Code (Guide for Students)

Follow this systematic approach:

1. Identify variables: Note every variable and its initial value
2. Trace loops: Execute loops iteration by iteration, updating variables
3. Track function calls: Follow the code into functions and back
4. Watch for string operations: String slicing and concatenation are common traps

Example 1 — Simple Loop:

for i in range(1, 5):
    print(i * 2)

Output:

2
4
6
8

(range(1,5) gives 1,2,3,4 — 5 is excluded)

Example 2 — String Slicing:

s = 'PYTHON'
print(s[1:4])
print(s[::-1])

Output:

YTH
NOHTYP

(s[1:4] → characters at index 1,2,3; s[::-1] → reversed string)

Example 3 — Nested Loop:

for i in range(1, 4):
    for j in range(1, 4):
        print(i * j, end=' ')
    print()

Output:

1 2 3 
2 4 6 
3 6 9 

1. range() endpoint: range(n) gives 0 to n-1, NOT 0 to n
2. Integer division: 7//2 = 3 (not 3.5)
3. String index: Starts at 0, not 1
4. end=' ': Suppresses newline in print, keeps output on same line
5. Mutable vs immutable: Lists can change inside functions; strings/tuples cannot