Looping the Loop: Automating Boring Work with Iterations

LOOPING THE LOOP: AUTOMATING BORING WORK WITH ITERATIONS If a program needs to process a list of 1,000 files, writing the processing code 1,000 times is inefficient. In programming, repeating tasks is handled using loops, also known as iterations. THE TWO KEY LOOP TYPES 1. THE FOR LOOP Use a "for" loop when you know the exact number of iterations beforehand. Python Example: for i in range(5): print("Iteration:", i) This loop runs exactly 5 times, incrementing "i" from 0 to 4. 2. THE WHILE LOOP Use a "while" loop to repeat a task until a specific condition becomes false. Python Example: tickets_left = 3 while tickets_left > 0: print("Ticket sold.") tickets_left = tickets_left - 1 The loop checks "tickets_left > 0". After 3 iterations, the variable reaches 0, the condition evaluates to false, and the loop terminates. BREAK AND CONTINUE KEYWORDS You can control loop execution dynamically using "break" and "continue": - break: Instantly exits the loop, skipping any remaining iterations. - continue: Skips the rest of the code in the current iteration and jumps to the next cycle. Break Example: for num in range(1, 10): if num == 5: break print(num) This prints 1, 2, 3, 4, then exits when num equals 5. Continue Example: for num in range(1, 6): if num == 3: continue print(num) This prints 1, 2, 4, 5, skipping 3. References: "Python Keywords.pdf" & Ray Dawson, "Programming in ANSI C", Section 7: Other Control Flow Statements.