CHAPTER 8: ARRAYS

EXAMPLE ON PAGE:256

In [1]:
 
x=5
x=10
print "x=%d\n" % (x)                        #prints 10

x=10

EXAMPLE ON PAGE:257-258

In [2]:
 
sum=0
marks=[]                             #array declaration
for i in range(30):
    marks.append(0)
for i in range(0,30,1):
    print "Enter marks"
    marks[i]=eval(raw_input())       #store data in array
for i in range(0,30,1):
    sum=sum+marks[i]
avg=sum/30
print "Average marks=%d\n" % (avg)

Enter marks
98
Enter marks
88
Enter marks
97
Enter marks
96
Enter marks
87
Enter marks
89
Enter marks
80
Enter marks
86
Enter marks
95
Enter marks
99
Enter marks
90
Enter marks
100
Enter marks
99
Enter marks
94
Enter marks
85
Enter marks
84
Enter marks
92
Enter marks
91
Enter marks
87
Enter marks
76
Enter marks
75
Enter marks
96
Enter marks
83
Enter marks
80
Enter marks
93
Enter marks
79
Enter marks
70
Enter marks
78
Enter marks
85
Enter marks
86
Average marks=87

EXAMPLE ON PAGE:261

In [2]:
 
num=[]
for i in range(40):
    num.append(0)
for i in range(0,40,1):                            #be carefull about the size of the array
    num[i]=i

EXAMPLE ON PAGE:261-262

In [3]:
 
def display(m):
    print "%d" % (m)
marks=[55,65,75,56,78,78,90]
for i in range(0,7,1):
    display(marks[i])

55
65
75
56
78
78
90

EXAMPLE ON PAGE:263

In [4]:
 
def show(n):
    print "%d" % (n)
def disp(n):
    show(n)                                             #calls show()
marks=[55,65,75,56,78,78,90]
for i in range(0,7,1):
    disp(marks[i])

55
65
75
56
78
78
90

EXAMPLE ON PAGE:263-264

In [5]:
 
i=3
j=1.5
k='c'
print "Value of i=%d\n" % (i)
print "Value of j=%f\n" % (j)
print "Value of k=%c\n" % (k)
x=id(i)
y=id(j)
z=id(k)
print "Original address in x=%u\n" % (x)
print "Original address in y=%u\n" % (y)
print "Original address in z=%u\n" % (z)
x+=1
y+=1
z+=1
print "New address in x=%u\n" % (x)
print "New address in y=%u\n" % (y)
print "New address in z=%u\n" % (z)

Value of i=3

Value of j=1.500000

Value of k=c

Original address in x=21147312

Original address in y=88181272

Original address in z=21311640

New address in x=21147313

New address in y=88181273

New address in z=21311641

EXAMPLE ON PAGE:265

In [6]:
 
arr=[10,20,30,45,67,56,74]
i=id(arr[1])
j=id(arr[5])
print "%d %d\n" % (j-i,arr[5]-arr[1])

-432 36

EXAMPLE ON PAGE:266

In [7]:
 
arr=[10,20,36,72,45,36]
j=id(arr[4])
k=id(arr[0+4])                                              #didn't get any other way
if j==k:
    print "The two pointers point to the same location\n"
else:
    print "The two pointers do not point to the same location\n"

The two pointers point to the same location

EXAMPLE ON PAGE:267

In [8]:
 
num=[24,34,12,44,56,17]
for i in range(0,6,1):
    print "element no.%d" % (i)
    print "address=%u\n" % (id(num[i]))

element no.0
address=21147060

element no.1
address=21146940

element no.2
address=21147204

element no.3
address=21146820

element no.4
address=21146676

element no.5
address=21147144

EXAMPLE ON PAGE:268

In [10]:
 
num=[24,34,12,44,56,17]
for i in range(0,6,1):
    print "address=%u" % (id(num[i]))
    print "element=%d\n" % (num[i])

address=21147060
element=24

address=21146940
element=34

address=21147204
element=12

address=21146820
element=44

address=21146676
element=56

address=21147144
element=17

EXAMPLE ON PAGE:268

In [11]:
 
num=[24,34,12,44,56,17]
j=id(num[0])                                      #assign address of zeroth element
for i in range(0,6,1):
    print "address=%u" % (id(num[i]))
    print "element=%d\n" % (num[i])              

address=21147060
element=24

address=21146940
element=34

address=21147204
element=12

address=21146820
element=44

address=21146676
element=56

address=21147144
element=17

EXAMPLE ON PAGE:270

In [12]:
 
def display(j,n):
    for item in j:
        print "element=%d\n" % (item)
num=[24,34,12,44,56,17]
display(num,6)

element=24

element=34

element=12

element=44

element=56

element=17

EXAMPLE ON PAGE:271

In [13]:
 
num=[24,34,12,44,56,17]
for i in range(0,6,1):
    print "address=%u" % (id(num[i]))
    print "element=%d %d" % (num[i],num[i])           #no other way
    print "%d %d\n" % (num[i],num[i])

address=21147060
element=24 24
24 24

address=21146940
element=34 34
34 34

address=21147204
element=12 12
12 12

address=21146820
element=44 44
44 44

address=21146676
element=56 56
56 56

address=21147144
element=17 17
17 17

EXAMPLE ON PAGE:272

In [14]:
 
stud=[[0,0],[0,0],[0,0],[0,0]]
for i in range(0,4,1):
    print "Enter roll no. and marks"
    stud[i][0]=eval(raw_input())
    stud[i][1]=eval(raw_input())
for i in range(0,4,1):
    print "%d %d\n" % (stud[i][0],stud[i][1])

Enter roll no. and marks
1206030
100
Enter roll no. and marks
1206007
95
Enter roll no. and marks
1206034
97
Enter roll no. and marks
1206026
88
1206030 100

1206007 95

1206034 97

1206026 88

EXAMPLE ON PAGE:275

In [15]:
 
s=[[1234,56],[1212,33],[1434,80],[1312,78]]
for i in range(0,4,1):
    print "Address of %dth 1-D array=%u\n" % (i,id(s[i]))

Address of 0th 1-D array=88430392

Address of 1th 1-D array=89514192

Address of 2th 1-D array=88430712

Address of 3th 1-D array=88430312

EXAMPLE ON PAGE:277

In [16]:
 
s=[[1234,56],[1212,33],[1434,80],[1312,78]]
for i in range(0,4,1):
    for j in range(0,2,1):
        print "%d" % (s[i][j])
    print "\n"

1234
56


1212
33


1434
80


1312
78

EXAMPLE ON PAGE:277-278

In [18]:
 
s=[[1234,56],[1212,33],[1434,80],[1312,78]]
p=[]
for i in range(2):
    p.append(0)
for i in range(0,4,1):
    p=s
    pint=p
    print "\n"
    for j in range(0,2,1):
        print "%d" % (pint[i][j])


1234
56


1212
33


1434
80


1312
78

EXAMPLE ON PAGE:279-280

In [20]:
 
def display(q,row,col):
    for item in q:
        print item
    print "\n"
a=[[1,2,3,4],[5,6,7,8],[9,0,1,6]]
display(a,3,4)

[1, 2, 3, 4]
[5, 6, 7, 8]
[9, 0, 1, 6]

EXAMPLE ON PAGE:281-282

In [21]:
 
arr=[]
for i in range(4):
    arr.append(0)
i=31
j=5
k=19
l=71
arr[0]=i
arr[1]=j
arr[2]=k
arr[3]=l
for m in range(0,4,1):
    print "%d\n" % (arr[m])

31

5

19

71

EXAMPLE ON PAGE:282

In [22]:
 
a=[0,1,2,3,4]
print "%u %u %d\n" % (id(id(a[0])),id(a[0]),a[0])

88518416 21147348 0