Computers tend to be great at repetitive tasks. Further, repetitive tasks are relatively easy to program. You write code for the task once, then you place that task in a loop. A loop will try to repeat itself forever, but you usually don’t want that. So you write a control structure with a condition statement. Either the loop will run while the condition is true, or it will stop when the condition is true, depending on how the structure is written.
Below is a conditional loop statement. It will continue to increase the production until the step variable has reached the value of 10. The step +=1 increases the step variable by 1 each time this loop runs.
# Initialize variable
production = 1.0
step = 1
# Run loop
while(step < 10): # Condition statement
production = production * 2.5
print 'Production =', production
step += 1
Activity
- Write and run the above program.
- Modify the program to run for exactly 30 steps.
Leveling Up
- Write a loop within a loop. This is a common programming practice. For example, the top level loop might run a calculation that occurs for each country, while the second level loop might run a calculation that occurs for each province to state.
Further Reading
- Python While Loops (W3schools)
- Python For Loops (W3schools)