Concise Python tutorial-6. Control Flow

 

Concise Python tutorial --- 6. Control Flow

 

In python, there are three control flow statements: if, for, and while.

If statement

The IF statement is used to detect a condition. If the condition is true, the program jumps to execute a statement block (called the if statement block ), otherwise, the program will jump to execute another statement block (else statement block ). Else clauses are optional.

Num1 = 1;

Num2 = 2;

If num1> num2:

Print (u'num1 is greater than num2. ');

Elif num1 = num2:

Print (u'num1 equals num2. ');

Else:

Print (u'num1 is smaller than num2. ');

Print U "program execution ends. ";

Note that Elif and else are optional. The simplest if statement is as follows:

If true:

Print 'true ';

You can also use the if statement in the IF statement block. This internal if statement is called a nested if statement.

Num1 = 1;

Num2 = 2;

If num1 <num2:

If num2 = 2:

Print u'num2 is equal to 2. ';

Else:

Print u'haha. ';

Note: Python does not have the switch statements in C/C ++, Java, and C #. You can use the IF-Elif-else statement to indirectly implement the switch function.

While statement

The while statement allows you to execute a piece of code repeatedly. This is similar to the while in C/C ++, Java, and C. The difference is that the while statement of python can have an optional else clause.

Num = 10;

While num> 0:

Print "num =", num;

Num = num-1;

Else:

Print U "num is less than or equal to 0. ";

For statement

Num = 1;

For I in range (1, 5 ):

Print "I =", I;

I = I + 1;

Else:

Print "over ";

Note: In the for and while loops of Python, The else statements (as long as there are else statements) after the loops exit ).

Break and continue statements

Similar to C/C ++, Java, and C #, Python also contains the break and continue statements, which are used to forcibly end loop execution.