Python Learning (8)

Exit the Double loop:
Way 1:try--except

try:    for i in range(5):        for j in range(5):            if i==3 and j ==3:                raiseexcept:    print(1)pass

Mode 2: Return of function implementation

def fun():    for i in range(5):        for j in range(5):            print(i,j)            if i==3 and j ==3:                return Truefun()

Mode 3: Multi-layer break

for i in range(5):    for j in range(5):        for k in range(5):            if i == j == k == 3:                break            else:                print (i, ‘----‘, j, ‘----‘, k)        else: continue        break    else: continue    break

Exercise 12: Enter 3 digits to sum up to 3 numbers, ending the program

result = 0for i in range(3):    number = input("please input number: ")    result += int(number)print(result)习题13、 用户输入不同的数据，当输入的数据达到3个数字的时候，求和结束程序。（数字可以是整数）提示：判断是否整数的方法，isdigit()遍历所有的输入数据，判断是否在0-9的字符串范围内方式1： #coding=utf-8result = 0count = 0while True:    s = input("please input the number: ")    for v in s:        if v not in "0123456789":#如果不是数字跳出当前循环            break    else:        count+=1        result += int(s)    if count ==3:        breakprint(result)

Method 2: First define a function to judge the number

#encoding=utf-8def is_int(num):    for n in num:        if n not in "0123456789":            return Falsereturn Trueresult = 0number_count = 0while True:    s = input("please input the number: ")    if is_int(s):        result += int(s)        number_count += 1      if number_count == 3:        break print(result)

Method 3: Use the IsDigit () function

result1 = 0count1=0while True:    s = input("please input the number: ")    if s.isdigit():        count1+=1        result1 += int(s)    if count1 ==3:        breakprint(result1)

Exercise 14: Iterating through the output of a matrix with nested lists
Mode 1:

l = [     [1,2,3],     [4,5,6],     [7,8,9]]for i in l:    for j in i:        print(j,end=" ")    print()

Mode 2:

for i in range(len(l)):    for j in range(len(l[i])):        print(l[i][j],end = " ")    print()

Exercise 15: The sum of the positive and inverse diagonals of nested lists
The sum of the positive diagonal

l = [     [1,2,3],      [4,5,6],      [7,8,9]      ]rusult = 0for i in range(len(l)):    for j in range(len(l[i])):        if i==j:            rusult += l[i][j]print(rusult)

The sum of the inverse diagonal

rusult = 0for i in range(len(l)):    for j in range(len(l[i])):        if (i+j)==2:            rusult += l[i][j]print(rusult)

Exercise 16: Finding the sum of the four elements of the matrix
L = [
[1,2,3,4,5],
[1,2,3,4,5],
[1,2,3,4,5],
[1,2,3,4,5],
[1,2,3,4,5]
]

Method 1:

1, line 1th and line 5th all elements sum
2. Other rows as long as the 1th and 5th columns are summed

rusult = 0for i in range(len(l)):    for j in range(len(l[i])):        if i == 0 or i == 4:            rusult += l[i][j]        else:            if j==0 or j==4:                rusult += l[i][j]print(rusult)

Method 2: Sum of all elements minus the sum of the intermediate matrices

l = [     [1,2,3,4,5],      [1,2,3,4,5],      [1,2,3,4,5],     [1,2,3,4,5],     [1,2,3,4,5]  ]matrix_element_sum = 0sub_matrix_element_sum = 0for i in range(len(l)):    for j in range(len(l[i])):        matrix_element_sum += l[i][j]result_mid = 0for i in range(len(l)):    for j in range(len(l[i])):        if i == 0 or i ==4:            continue        else:            if j !=0 and j!=4:                sub_matrix_element_sum += l[i][j]print(matrix_element_sum - sub_matrix_element_sum)

Python Learning (8)