Python string Method - format()

The format() method in Python strings is used to format a string by replacing placeholders in the string with corresponding values. The placeholders are marked by curly braces {} and can contain optional format specifiers.

The syntax for the format() method is as follows:

string.format(value1, value2, ...)

Here, string is the string that we want to format, and value1, value2, etc. are the values that we want to substitute for the placeholders in the string.

Example:

# Defining a string with placeholders
my_string = "My name is {} and I am {} years old"

# Using the format() method to replace the placeholders
result = my_string.format("Alice", 30)

print(result)   # Output: "My name is Alice and I am 30 years old"

In the above example, the format() method is used to replace the two placeholders {} in the string "My name is {} and I am {} years old" with the values "Alice" and 30, respectively. The resulting string "My name is Alice and I am 30 years old" is then assigned to the variable result. The output of the program is "My name is Alice and I am 30 years old".

We can also use named placeholders in the string by providing names inside the curly braces. Example:

# Defining a string with named placeholders
my_string = "My name is {name} and I am {age} years old"

# Using the format() method to replace the named placeholders
result = my_string.format(name="Bob", age=25)

print(result)   # Output: "My name is Bob and I am 25 years old"

In this example, the placeholders in the string "My name is {name} and I am {age} years old" are named "name" and "age". The format() method is used to replace these named placeholders with the values "Bob" and 25, respectively. The resulting string "My name is Bob and I am 25 years old" is then assigned to the variable result. The output of the program is "My name is Bob and I am 25 years old".

We can also use format specifiers to control the formatting of the substituted values. For example, we can use the format specifier :.2f to format a floating-point number with two decimal places. Example:

# Defining a string with a formatted value
my_string = "The value of pi is approximately {:.2f}"

# Using the format() method to replace the formatted value
result = my_string.format(3.141592653589793)

print(result)   # Output: "The value of pi is approximately 3.14"

In this example, the placeholder {:.2f} in the string "The value of pi is approximately {:.2f}" specifies that the substituted value should be formatted as a floating-point number with two decimal places. The format() method is used to replace this placeholder with the value 3.141592653589793, which is then formatted as "3.14". The resulting string "The value of pi is approximately 3.14" is then assigned to the variable result. The output of the program is "The value of pi is approximately 3.14".