nested loops

1. 巢狀 for 迴圈語法。

   for iterating_var in sequence:
   	for iterating_var in sequence:
   		statement1(s)
   	statement2(s)
   

2. 範例：列印直角三角型。

   [dywang@deyu zzz]$ cat loop4.py 
   #!/usr/bin/env python3
   # coding: utf-8
   
   num = int(input("Enter a number: "))
   for i in range(1, num+1):
   	for j in range(1, num+1):
   		if j<=i: print("* ", end="")
   	print()
   

3. 列印直角三角型程式執行結果。

   [dywang@deyu zzz]$ ./loop4.py 
   Enter a number: 5
   *
   * *
   * * *
   * * * *
   * * * * *
   

4. 巢狀 while 迴圈語法。

   while expression1:
   	while expression2:
   		statement1(s)
   	statement2(s)
   

5. 範例：列印直角三角型。

   [dywang@deyu zzz]$ cat loop5.py
   #!/usr/bin/env python3
   
   num = int(input("Enter a number: "))
   i = j = 1
   while(i<num+1):
   	while(j<num+1):
   		if j<=i: print("* ",end="")
   		j += 1
   	print()
   	i += 1
   	j = 1
   

6. 列印直角三角型程式執行結果。

   [dywang@deyu zzz]$ ./loop5.py 
   Enter a number: 5
   *
   * *
   * * *
   * * * *
   * * * * *