Let’s say that you want to search for a substring within a string object. Nothing easier. In Python, there is a polymorphic operator named in which allows you to do just that! Let’s try it!
>>> s1 = 'Dan is a web developer based within the EU.'
>>> 'Dan' in s1
True
>>> 'Dumitrache' in s1
False
>>> 'EU' in s1
True
>>> 'Canada' in s1
False
First of all let’s see what translation means in Python. The translate() method returns a string that is translated (one or more characters were changed).
>>> s1 = 'Dan Dumitrache'
>>> s1_tr = s1.maketrans('D', 'M')
>>> s1.translate(s1_tr)
'Man Mumitrache'
Let’s say you need to iterate over of all the characters of a string object and modify every character in some way. You can do it using the for loop.
>>> s1 = 'Dan Dumitrache'
>>> for i in s1:
... print(i, ' ; ')
...
D ;
a ;
n ;
;
D ;
u ;
m ;
i ;
t ;
r ;
a ;
c ;
h ;
e ;
Let’s say you need to accept user input but without the white spaces. The strip() method of the string object can be used to delete any white space characters from a string.
>>> s1 = ' Whitespace '
>>> s1
' Whitespace '
>>> s2 = s1.strip()
>>> s2
'Whitespace'
Let’s say you want to reverse the content of a string in Python. For example instead of “Dan” you want to be displayed “naD” (in reverse). You can do it by using slice notation. You select all of the individual characters but in reverse order.
>>> s1 = 'Dan'
>>> s2 = s1[::-1]
>>> s2
'naD'
Let’s consider that you need to replace a substring of a string with a new substring.
>>> s1 = 'Dan is 39 years old. 39 is a nice age although other people think that you are old when you are 39 years old
>>> s2 = s1.replace('39', '40')
>>> s2
'Dan is 40 years old. 40 is a nice age although other people think that you are old when you are 40 years old.'
Let’s consider you want to convert a floating point number into an integer. There are two ways of doing that.
You can truncate the floating point number to just the portion before the decimal point. You can do that with the int() function which truncates the number towards zero.
>>> fpn = 57.83
>>> int(fpn)
57
Let’s say you want to compare two string to see if they have the same value. You can do it using the comparison operator is equal to which is represented by == (two equal signs).
>>> s1 = 'Dan'
>>> s2 = 'Dumitrache'
>>> if s1 == s2:
... print('Strings are equal!')
... else:
... print('Strings are not equal!')
...
Strings are not equal!
Let’s say you may want to construct a big string from smaller strings in Python. The solution is simple and it is called concatenation. As in Math, you can use the addition operator, which is +, to put one or more strings together and return a larger string.
>>> s1 = 'My name '
>>> s2 = 'is Dan.'
>>> new_string = s1 + s2
>>> print(new_string)
My name is Dan.
Let’s say you want to add a string and a number together. For example you have the string “The number of monkeys = ” and the number 17. You would like to add them together and display “The number of monkeys = 17”.