python string operations

Posted by: instanceofjava Posted date: 4:03 PM / comment : 0

  • In python, we have some operations that perform the specified operations on strings.
  • In this, the string must enclose with the codes that might be single or double.
  • Here are some python string operations.

1.  String assignment operator:

  • In this operator, the string is assigned to any of the variables.
  • The string may be in single or double codes.
  • It is represented by " =" equal to symbol.
Syntax: string ="any variable."

Example:  string1="python"
                  string2="java"

In the above example, we assign a "python" to string 1 and "java" to string 2 by using the" =" symbol.

# write a python program for the string assignment operator.

  1. str1="welcome to python"
  2. str2="Today topic is string operator"
  3. str3="python is easy  language"
  4. print(str1)
  5. print(str2)
  6. print(str3)
output:  welcome to python
             Today topic is string operator
             Python is easy to language



2. Cancatenate operator:

  • This operator has used to cancate the strings.
  • Concatenation means joining or combing the strings by using the plus symbol between the strings.
  • It is represented by the symbol " +".
       Syntax:  (str1+str2)

       Example:   "Hello"  +"world"
  •  Result is : "Helloworld"

#Write a python program using string cancatenate operator.

  1. str1="a"
  2. str2="is"
  3. str3="alphabet"
  4. print(str1+str2+str3)
output: aisaphabet


3. String repetition operator: 

  • In this operator, the string is repeated the number of times that we declare in the code.
  • It is represented by the symbol "*".
Syntax:  str*n    Here n is the number of times that the string can be repeated.

Example: str="apple"
                 str*2
The result is: apple apple
  • here we declare the string as apple it should be repeated for 2 times.

#Write a python code using the string repetition operator.

  1. str="welcome"
  2. print(str*5)
output: welcome welcome welcome


       

       4.Slicing operator:  

  • In this slicing operator, the strig is divided according to the given index values.
  • The string can y accessed by using the index.
  •  It is having positive index and negative index values.
  • Positive values start from  0 from left to right.
  • The negative index starts from -1 from right to left.
  • [:] this gives all values in the index 0 to end. 
  • The slicing never shows the error, if the index is out of range, it shows an empty list[].  

Syntax: str[]

Example:   str="string"
                   str[0]=s
                   str[1]=t
                   str[-1]=g
  • In the above example, the s index is 0 so it returns s when we write str[0].

#write a python code for slicing operator.

  1. str="coding"
  2. print(str[0])
  3. print(str[-1])
  4. print(str[1:6])
  5. print(str[1:])
  6. print(str[:3])
  7. print(str[1:-4])
  8. print(str[-3])
output:  c
             g
             oding
             oding
             cod
              o
              i                                                                                 


                                       

5. String comparison operator:

  • In the string comparison operator, we compare the strings.
  • In this, we have 2 operator
     1.Equal to(==): If both the strings are the same then it returns true else false.
  • It is represented by the symbol "==".
     Syntax:str1==str2.

       2.not equal(!=): If both strings are not the same then it true else false.
  • It is represented by the symbol "!=".
Syntax:  str1!=str2

#write a python coding using the python string comparison operator.

  1. str1="my name is A"
  2. str2="my name is B"
  3. str3="my name is A"
  4. str4="apple"
  5. str5="apple"
  6. print(str1==str2)
  7. print(str1==str1)
  8. print(str4==str5)
  9. print(str4!=str1)
  10. print(str3!=str2)
output: false
            true
            true
            true
            true



6. Membership operator:

  • In the membership operator, we check the string that is declared in the code is present in the given list or not.
  • There are 2 operators in membership.
  1. In:  It tells that the string is present in the given list.If it is present returns true else false.
  2. Not in: It tells that the string is not present in the given list returns true else false.
Example: str="string"
                r in the str
       The result is: true

#write python code using membership operator.

  1. str="Hello world"
  2. print("H" in str)
  3. print('s' in str)
  4. print("a" not in str)
output:  true
             false
             true



7. Escape sequence operator:

  • This operator is used when an unallowed character is present in the given string.
  • It is represented by the "\" symbol called backslash. 

Write a python program for escape sequence operator.

  1. str="welcome to \"python\" classes"
  2. print(string)
output: welcome to "python" classes





8.String formatting operator:

  • It is used to format the string as per our requirement.
  • There are different types of formats.
  • It is denoted by that "%" symbol.
  • Each format has its own meaning.
%d:  used for sign decimal integer.
%s: used for string.
%f: used for floating.
%u: used for unsigned decimal integer.
%c: used for the character.

#write a python code using the string formatting operator.

  1. name="abc"
  2. marks=78
  3. str1='hi % s'%(name)
  4. print(str1)
  5. str2='hi% s,my marks is %f'%(name,marks)
  6. print(str2)
output: hiabc,my marks is 78.000000


python string methods

Posted by: instanceofjava Posted date: 5:48 PM / comment : 0

 Python string methods:

  • Before going to string methods first of all we have to know what is meant by string.
  • A "String is a set of or group of characters."
  • The string always must be closed with single, double, or triple codes.
  • Triple codes (''' ''') are used for multi-line purposes.
  • In python, we are having some string functions, that are used to operate on strings.
  • As the string is immutable it always returns the new values only. The old values cannot be replaced.
  • The string function is defined as str().

Example:

#1.write python code using the str() methods.

  1. s'"Hello"
  2. print(s[0])
  3. print(s[1])
  4. print(s[2])
  5. print(s[3])
  6. print(s[4])
output:  H
              e
              l 
              l
             o


#2. write a python code using str() functions.

  1. str="Hello"
  2. print(str.lower())
  3. print(str.upper())
  4. print(str.count(str))
output: hello
             HELLO
              1



  • In the following table, we will find more functions and their respective actions in the string.

MethodDescription
len()used to determine the length of the string.
isalnum()used to define the string is alphanumeric.
islower()To define a string is in small letters.
isupper()To define a string is in capital letters.
isnumeric()The string consists of only numbers.
istitle()The string is in the title case.
isspace()The string has only white space.
find()Searches the string value and returns the position.
format()Formats specified values in a string
format_map()Formats specified values in a string
index() returns the position of string where it was found
count()Returns the number of times string occurs.
stratswith() the string starts with the given prefix.
isdecimal() all characters in the string are decimals
isdigit() all characters in the string are digits
isidentifier()Returns True if the string is an identifier
endswith() all characters in the string end with the given suffix. 
encode()it encodes the string.
isprintable()all characters in the string are printable.
capitalize()it returns all the capital strings.
center()Returns the center string. 
_contain_() the string we check is contained in another string or not.
join()Joins the elements of the string.
ljust()Returns a left-justified version of the string
hash()Returns the hash value of the given object.
lstrip()Returns a left trim version of the string
maketrans()Returns a translation table to be used in translations
partition()Returns a tuple where the string is parted into three parts
replace() string where a value is replaced with another value.
rfind()Search the string and returns the last position.
rindex()Search the string and returns the last position.
rjust()Returns a right-justified version of the string
rpartition()Returns a tuple where the string is parted into three parts
rsplit()Splits the string at the specified separator, and returns a list
rstrip()Returns a right trim  of the string
split()Splits the string at the specified separator, and returns a list
splitlines()Splits the string at line breaks and returns a list
id()Returns the identity of the string.
strip() It trims the space between the strings.
swap case()In this, the lower case becomes the upper case and vice versa
title()Converts the first character of each word to upper case
translate()Returns a translated string
upper()Converts a string into the upper case.
zfill()Fills string with a specified number of 0's at the beginning.

C initialize an array

Posted by: saidesh Posted date: 8:38 PM / comment : 0 ,

  • Array is collection of similar data items.
  • An array can hold multiple values of same type of data
  • In c programming language an array can be declared as datatype arrayName [ arraySize ]; 
  • In c , while declaring an array we need to specify type of array , name of array and size of the array.
  • One can directly initialize an array while declaring itself with some values
  • int arrayVariable[2]=[10,20];
  • int count[]=[1,2,3,4,5]
  • directly initialize an array of particular : count[3]=10
  • Let us discuss about how to initialize an array with some default values.
  • Using for loop or while loop we can iterate an array and by accessing each index we can assign values 
  • If we are not initializing an array and try to print all the values then it will print some garbage values.
  • c initialize array of ints

#1Write a C program to declare an array and print default values
  1. #include <stdio.h>
  2. // write a c program to explain how to initialize an array
  3. int main () {

  5.    int number[ 15 ]; 
  6.    int i,k;
  7.    
  8.    
  9.    for (k = 0; k < 15; k++ ) {
  10.       printf("Array[%d] = %d\n", k, number[k] );
  11.    }
  12.  
  13.   getch();
  14. }


Output:
  1. Array[0] = -1551778920
  2. Array[1] = -2
  3. Array[2] = 1971427546
  4. Array[3] = 1971495162
  5. Array[4] = 5189464
  6. Array[5] = 5181048
  7. Array[6] = 2686776
  8. Array[7] = 1971494685
  9. Array[8] = 0
  10. Array[9] = 0
  11. Array[10] = 2686832
  12. Array[11] = 200
  13. Array[12] = 192
  14. Array[13] = 7161720
  15. Array[14] = 48


#2 write a C Program to initialize an array values to 0 (zeros).

initialize an array in c


Output:
  1. Array[0] = 0
  2. Array[1] = 0
  3. Array[2] = 0
  4. Array[3] = 0
  5. Array[4] = 0
  6. Array[5] = 0
  7. Array[6] = 0
  8. Array[7] = 0
  9. Array[8] = 0
  10. Array[9] = 0
  11. Array[10] = 0
  12. Array[11] = 0
  13. Array[12] = 0
  14. Array[13] = 0
  15. Array[14] = 0

spilt function in python

Posted by: instanceofjava Posted date: 12:22 PM / comment : 0

 Split function: 

  • The split() function is used to split the string by separating them with the split().
  • The split()  method contains the different separators  like comma(,) colon(:) semicolon(;)  and space also.
  • By default when we write split() function it will separate the values by "space ".
  • After splitting the string it returns a list of strings.
Syntax: str.split(separator,max split)
  • Example:
  • y=[int(x) for x in input("enter the 2 numbers:").slipt(",")]
  • Here, the 2 numbers are 10 2 by using split(",") these numbers are separated by"," as 10,5.
  • There are  3 parameters in the split() method
  1. separator: It separates the string by using separators if we do not use then by default it takes space.
  2. max split:  It is used to split the string by the max number of times. By default, it takes 1 i.e no limit for splitting. 
  3. Returns: After splitting the string it returns the list of string values.

# write a python code using the split().

  1. a="apple is a fruit"
  2. b=" dog is a animal"
  3. c="python is easy to learn"
  4. print(a.split())
  5. print(b.split())
  6. print(c.split())
output: ['apple' , 'is' , 'a' , 'fruit' ]
            ['dog'  ,'is'  ,'a', 'animal']
            ['pthon'  , 'is'   , 'easy'  ,'to' , 'learn']



python Ternary operator

Posted by: instanceofjava Posted date: 6:36 PM / comment : 0

Ternary operator: 

  • The ternary operator is defined as the operator that evaluates the conditions to find the final result.
  • It evaluates more than one expression.
  • A  single line code is written according to the condition.
syntax:  x= first value if condition else second value.
In this syntax, if the first value satisfies the condition then it returns the x value, if the first value doesn't satisfy the condition then it goes to the else part and checks the second condition.

Example: x=20 if 5<10 else 30 we get the result as 20.
Because here condition 5<10 is grue so it returns the x value as 10.

  • There is another syntax for the ternary operator when there are more than 2 conditions i.e;
  • syntax: x= first value if condition 1 else second value if condition 2 else third value.
Example: x=1 if 20>30 else 2 if 50>60 else  10. 
                The result is  10.
  • In the ternary operator, we can perform a nested loop also.
  • We can reduce the length of the code by using this ternary operator, in this operator we write a code in a single line.
  • So time is saved and less complexity in the code.

#write a python program for integers using the ternary operator.

  1. a=8
  2. b=9
  3. max= b if b>a else a.
  4. print(max)
output: 9



python not operator

Posted by: instanceofjava Posted date: 6:01 PM / comment : 0

 Python not operator:

  • python not operator is the complement of the given value i.e; if the value is true then it returns false and if the value is false then it returns true.
  • When we  apply the not operator we get result  in  boolean type .
  • example:
                 x=10 
                 not x, then the result is false because x=10 is true so not x is false.
  • syntax:(not x).

 # write a python program using not operator.

  1. x="python"
  2. y="java''
  3. print(not x==y)
output: true

 

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