while — Advanced Playground

Starts a loop that repeats as long as its condition is true

Python Playground

def tokenize(expression):
    tokens = []
    i = 0
    while i < len(expression):
        ch = expression[i]
        if ch.isspace():
            i += 1
        elif ch.isdigit():
            num = ""
            while i < len(expression) and expression[i].isdigit():
                num += expression[i]
                i += 1
            tokens.append(("NUM", int(num)))
        elif ch in "+-*/":
            tokens.append(("OP", ch))
            i += 1
        else:
            i += 1
    return tokens

result = tokenize("12 + 34 * 5")
for token in result:
    print(token)

Output

Click "Run" to execute your code

while loops are natural for parsers and state machines where the number of iterations depends on the input content, not just its length.

Challenge

Try modifying the code above to explore different behaviors. Can you extend the example to handle a new use case?

View all Advanced examples for while