4.4 Python vs C vs Java, and the final

Big ideas

• Python is interpreted and dynamically typed: you run source code directly and a variable can hold any type. C and Java are compiled and statically typed: every variable declares a type and mistakes are caught before running.
• Speed: compiled C runs many times faster than Python; Java sits between (compiled to bytecode, run by a virtual machine). Python wins on writing speed and libraries, which is why data science lives there.
• Memory: C makes you manage memory by hand (malloc/free); Java and Python collect garbage automatically. Python indents blocks; C and Java use braces and semicolons.
• Same idea, three spellings: a for loop, a function, a class look alike once you know one language. CSCI 132 continues in a compiled language.
• Final exam prep: it is the third equally weighted exam and centers on Unit 4 (NumPy, matplotlib, pandas), but the reading-code skills from Units 1–3 are assumed.

Code you should know

# Python
total = 0
for i in range(1, 6):
    total += i
print(total)

# C
# int total = 0;
# for (int i = 1; i <= 5; i++) { total += i; }
# printf("%d\n", total);

# Java
# int total = 0;
# for (int i = 1; i <= 5; i++) { total += i; }
# System.out.println(total);

15

Worked example

Common mistakes

• Calling Java “interpreted” or Python “compiled” without qualification: Python compiles to bytecode internally but is run by an interpreter; Java compiles to bytecode for the JVM.