An Introduction to Python For Undergraduate Engineers/While Loops

While loops will repeat a section of code whilst a logical test is true.

Instead of repeating something with a defined list of values or a set number of times, a while loop will happily continue repeating its section of code until a logical test is satisfied. Programs that run forever are to stop with Restart Shell in the IDLE or to hit the Control (or Ctrl) button and C (the letter) at the same time. For example:

    done = False             # Creates a variable and gives it the logical vlue 'False'
    count = 0                # Creates a variable and gives it integer value 0
    while done == False:     # Repeats following code until logical test no longer satisfied
        count = count + 1    # Adds 1 to value of count variable
        print("The value of count is... " + str(count))   # Prints value of count

The same code could also be written using != which means NOT EQUAL TO, for example:

    done = False             
    count = 0                
    while done != True:     
        count = count + 1    
        print("The value of count is... " + str(count))