# String Data Types In Details

In Python, a string is a sequence of characters that can be manipulated using various functions and methods.

## **Some of the main ways to manipulate strings:**

### **Slicing**:

Extracting a substring from a larger string by specifying a range of indices.

**Basic syntax is :** `str[start:end:step]`

* ```python
    string = "Hello"
    string[1:4]  # "ell"
    #starting from position 1 to 
    string[:4]   # "Hell"
    string[2:]   # "llo" 
    string[:]    # "Hello"
    
    '''You can use negative indices to slice from the end, and specify 
    a step to slice with a stride'''
    
    string = "Hello"
    string[-4:-1] # "ell"
    string[::-1]  # "olleH"
    string[::2]   # "Hlo"
    ```
    

### **String methods:**

Useful functions to manipulate strings(`lower()`,`upper()`, `split()`, `join()`, `replace()`, `find()` )

```python
string = 'Learn Python'
string.lower()  # returns 'learn python'
string.upper()  # returns 'LEARN PYTHON'

#string to list
string = 'Learn Python Programming'
print(string.split(' ')) # output =  ['Learn', 'Python', 'Programming']

#list to string
parts = ['Learn', 'Python', 'Programming']
string.join(parts) # output = 'Learn Python Programming'

string = 'Learn Python Programming'
string.replace('Python', 'Java') # output = 'Learn Java Programming'

string = 'Bitsnotion'.find('s')
print(abc)# output = 3
```

### **String formatting:**

Integrate variables into strings.

**Python offers various methods for string formatting:**

* The `f-strings` (available in Python 3.6+)
    
* The `str.format()` method
    
* The `%` operator (deprecated in Python 3)
    

```python
name = "Nirmal"
age = 23

print(f"Hello, my name is {name} and I'm {age} years old.")
print("Hello, my name is {} and I'm {} years old.".format(name, age))

# Both output =  "Hello, my name is Nirmal and I'm 23 years old."
```

### **Foat formatting options :**

**To use these options, build your expression within braces as follows:**

1. The float variable is what’s being formatted
    
2. A colon (**:**) separates what’s being formatted from the syntax used to format it
    
3. **. number** indicates the desired precision
    
4. A letter indicates the presentation type
    

![](https://cdn.hashnode.com/res/hashnode/image/upload/v1717344990429/d03f81dd-4b0b-41e2-b8e1-a27c1e3f52b5.png align="center")

```python
num = 1234.987123
print(f'{num:.2f}')#Output = 1234.99
```

**Some others mostly used presentation types:**

| **Type** | **Meaning** |
| --- | --- |
| **'e'** | Scientific notation. For a given precision **p**, formats the number in scientific notation with the letter ‘**e**’ separating the coefficient from the exponent. The coefficient has one digit before and **p** digits after the decimal point, for a total of **p + 1** significant digits. With no precision given, **e** uses a precision of **6** digits after the decimal point for [float](https://docs.python.org/3/library/functions.html#float), and shows all coefficient digits for [decimal](https://docs.python.org/3/library/decimal.html#decimal.Decimal). |
| **'f'** | Fixed-point notation. For a given precision **p**, formats the number as a decimal number with exactly **p** digits following the decimal point. |
| **'%'** | Percentage. Multiplies the number by 100 and displays in fixed (**'f'**) format, followed by a percent sign. |

```python
num = 1000.987123
print(f'{num:.3e}')#Output = 1.001e+03

decimal = 0.2497856
print(f'{decimal:.4%}') #Output = 24.9786%
```

### **String concatenation:**

Combine multiple strings using the + operator or .join() method.

```python
string1 = "Hello"  
string2 = "World!"

#method -1
print(string1 + string2) ## output = Hello World!
#method-2
string1 += string2
print(string1)  # output = Hello World!
#method-3
print("".join([string1, string2])) # HelloWorld!
```