Python conditional judgment and looping

Conditional judgment

Python's indentation rules, if the IF statement is true, the code is executed, you can also add an else statement, meaning, if the judgment is false, do not execute if the content, to the else executed

Num=num >=: (num) (): (num) ()

Of course, the above judgment is rough, can be used elif to make more detailed judgments

Num=num >=: (num) () num >=: (): ()

Elif is the else if abbreviation, can have more than one elif, so the IF statement after the XXX type is:

< condition judgment 1>: < perform 1>< condition judgment 2>: < execution 2>< condition 3: < execution 3>: < execution 4>

If statement execution has a feature, it is judged from the top down, if it is true on a certain judgment, the corresponding statement of the judgment executed, ignoring the remaining elif and else

If you can also abbreviate

If x:

Print (' true ')

As long as X is a non-0 value, a nonempty string, a non-empty list, and so on, it evaluates to true, otherwise it is false.

Input () read as a string

Cycle:

For loop

There are two types of Python loops, one is the for...in loop, and each of the elements in the list or tuple is iterated in turn to see an example

Names=[]i names: (i)

Jack

Lucy

Tom

So for the X in ... A loop is a statement that puts each element into the variable x and then executes the indented block.

Build number function range (), use method range (start number, end number, middle span), 0 start, n-1 end

Version 3.x has generated an iterator for the range (), not the output,

Calculation of the sum of 100

Sum=i (): Sum=sum+i (SUM)

The second kind of loop

While loop, as long as the condition is satisfied, the loop will not break and exit the loop if the condition is not satisfied. For example, we want to calculate the sum of all the odd numbers within 100, using the while loop

Sum=n=n>: Sum=sum+n n=n-(SUM)

Interrupt current loop Break, demo

Sum=n=n>: sum=sum+n n = n-n <: (n) (sum)

Continue end this cycle, continue execution

n=n<: n=n+ (N)

Print only odd numbers

n=n<: n=n+n% = =: (n)

Python conditional judgment and looping