String in Python – Examples and Operations

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Similar to other programming languages, Python also has a string data type. The string is a class that has various valuable methods. This tutorial will explain the declaration of string variables and various operations with examples.

How to declare the string?

In Python, a string can be declared using single, double, or triple quotes. Generally, we avoid triple quotes, used primarily for multiline strings. Following are a few declaration examples.

str = "Hello , i am a string";
 print(str);
 str = 'Hello , String with single quotes';
 print(str);
 str = """String with triple quotes"""
 print(str);

str = "Hello , i am a string";
 print(str);
 str = 'Hello , String with single quotes';
 print(str);
 str = """String with triple quotes"""
 print(str);

You can break a string into multiple lines when using triple quotes. With others, Python will throw an error while executing.

str = "Hello , 
     i am a string";
 print(str);

py Strings.py
   File "Strings.py", line 1
     str = "Hello ,
                   ^
 SyntaxError: EOL while scanning string literal

str = """String with 
                 triple quotes"""
 print(str);

Output->

str = """String with 
                 triple quotes"""
 print(str);

Accessing individual characters in a string.

Being an array of characters, we can access each string element. But we can not modify (strings are immutable) a character in the declared string as we can do with an array.

print elements->

str = """String with 
                 triple quotes"""
 print("Ele -> 1", str[1]);
 print("Ele -> 1", str[4]);

Output->

Ele -> 1 t
 Ele -> 1 n

Modify an element->

str = """String with 
                 triple quotes"""
 str[4] = 'g';

Output->

Traceback (most recent call last):
   File "Strings.py", line 5, in 
     str[4] = 'g';
 TypeError: 'str' object does not support item assignment

Few more substring/element operations –

str = "I am a string";
 last element in string
 print(str[-1]);
 get substring between 2 to 6 from start
 print(str[2:6]);
 get substring between 1st from start and 2nd from last
 print(str[1:-2]);

Output->

g
 am a
  am a stri

Errors while accessing a string-

Python has strict error checking while handling strings. A programmer may induce unintentional errors. E.g., index outside the range, wrong formats, etc. While executing, if any error case occurs, Python prints the errors. In the following code, we will show a few cases.

str = "I am a string";
 out of range
 print(str[-100]);

File "Strings.py", line 4, in 
     print(str[-100]);
 IndexError: string index out of range

 print(str[2,6]);

File "Strings.py", line 4, in 
     print(str[-100]);
 IndexError: string index out of range