app.py

import streamlit as st

# Dictionary of string methods with their explanations
string_methods = {
    'replace': {
        'syntax': "str.replace(old, new, count=-1)",
        'description': "Replaces all occurrences of old with new. Optional argument 'count' limits the number of replacements.",
        'example': "Example: 'hello world'.replace('world', 'Streamlit') -> 'hello Streamlit'"
    },
    'capitalize': {
        'syntax': "str.capitalize()",
        'description': "Capitalizes the first letter of the string.",
        'example': "Example: 'hello world'.capitalize() -> 'Hello world'"
    },
    'title': {
        'syntax': "str.title()",
        'description': "Converts the first character of each word to uppercase.",
        'example': "Example: 'hello world'.title() -> 'Hello World'"
    },
    'upper': {
        'syntax': "str.upper()",
        'description': "Converts all characters to uppercase.",
        'example': "Example: 'hello world'.upper() -> 'HELLO WORLD'"
    },
    'lower': {
        'syntax': "str.lower()",
        'description': "Converts all characters to lowercase.",
        'example': "Example: 'HELLO WORLD'.lower() -> 'hello world'"
    },
    'find': {
        'syntax': "str.find(sub, start=0, end=len(str))",
        'description': "Returns the lowest index of the substring if found, otherwise returns -1.",
        'example': "Example: 'hello world'.find('world') -> 6"
    },
    'strip': {
        'syntax': "str.strip([chars])",
        'description': "Removes leading and trailing characters (default is whitespace).",
        'example': "Example: ' hello world '.strip() -> 'hello world'"
    },
    'partition': {
        'syntax': "str.partition(sep)",
        'description': "Splits the string at the first occurrence of sep into a 3-tuple: (head, sep, tail).",
        'example': "Example: 'hello world'.partition(' ') -> ('hello', ' ', 'world')"
    },
    'count': {
        'syntax': "str.count(sub, start=0, end=len(str))",
        'description': "Returns the number of non-overlapping occurrences of a substring.",
        'example': "Example: 'hello world'.count('o') -> 2"
    },
    'casefold': {
        'syntax': "str.casefold()",
        'description': "Returns a casefolded copy of the string, which is more aggressive than lower() for case-insensitive comparisons.",
        'example': "Example: 'HELLO'.casefold() -> 'hello'"
    },
    'swapcase': {
        'syntax': "str.swapcase()",
        'description': "Swaps case: lowercase becomes uppercase and vice versa.",
        'example': "Example: 'Hello World'.swapcase() -> 'hELLO wORLD'"
    },
    'startswith': {
        'syntax': "str.startswith(prefix[, start[, end]])",
        'description': "Returns True if the string starts with the specified prefix, otherwise False.",
        'example': "Example: 'hello world'.startswith('hello') -> True"
    },
    'endswith': {
        'syntax': "str.endswith(suffix[, start[, end]])",
        'description': "Returns True if the string ends with the specified suffix, otherwise False.",
        'example': "Example: 'hello world'.endswith('world') -> True"
    },
    'isalpha': {
        'syntax': "str.isalpha()",
        'description': "Returns True if all characters in the string are alphabetic and there is at least one character, otherwise False.",
        'example': "Example: 'hello'.isalpha() -> True"
    },
    'isnumeric': {
        'syntax': "str.isnumeric()",
        'description': "Returns True if all characters in the string are numeric characters, otherwise False.",
        'example': "Example: '12345'.isnumeric() -> True"
    },
    'isalnum': {
        'syntax': "str.isalnum()",
        'description': "Returns True if all characters in the string are alphanumeric and there is at least one character, otherwise False.",
        'example': "Example: 'hello123'.isalnum() -> True"
    },
    'join': {
        'syntax': "str.join(iterable)",
        'description': "Concatenates the strings in the iterable using the string as a separator.",
        'example': "Example: ', '.join(['hello', 'world']) -> 'hello, world'"
    }
}

# Streamlit app
st.title("Explore Python String Methods")

# Method selection
method = st.selectbox("Choose a string method to learn about:", list(string_methods.keys()))

# Input for user string
user_input = st.text_input("Enter a string to see the method in action:", "hello world")

# Display method details
if method:
    st.write(f"### {method.capitalize()} Method")
    st.write(f"**Syntax:** `{string_methods[method]['syntax']}`")
    st.write(f"**Function:** {string_methods[method]['description']}")
    st.write(f"**Example:** {string_methods[method]['example']}")
    
    # Show output of the method based on user input
    if method == 'replace':
        old = st.text_input("Old substring:", "")
        new = st.text_input("New substring:", "")
        if old and new:
            result = user_input.replace(old, new)
            st.write(f"**Output:** `{result}`")
    elif method == 'capitalize':
        result = user_input.capitalize()
        st.write(f"**Output:** `{result}`")
    elif method == 'title':
        result = user_input.title()
        st.write(f"**Output:** `{result}`")
    elif method == 'upper':
        result = user_input.upper()
        st.write(f"**Output:** `{result}`")
    elif method == 'lower':
        result = user_input.lower()
        st.write(f"**Output:** `{result}`")
    elif method == 'find':
        substring = st.text_input("Substring to find:", "")
        if substring:
            result = user_input.find(substring)
            st.write(f"**Output:** `{result}`")
    elif method == 'strip':
        chars = st.text_input("Characters to strip (leave empty for whitespace):", "")
        result = user_input.strip(chars) if chars else user_input.strip()
        st.write(f"**Output:** `{result}`")
    elif method == 'partition':
        sep = st.text_input("Separator:", "")
        if sep:
            result = user_input.partition(sep)
            st.write(f"**Output:** `{result}`")
    elif method == 'count':
        substring = st.text_input("Substring to count:", "")
        if substring:
            result = user_input.count(substring)
            st.write(f"**Output:** `{result}`")
    elif method == 'casefold':
        result = user_input.casefold()
        st.write(f"**Output:** `{result}`")
    elif method == 'swapcase':
        result = user_input.swapcase()
        st.write(f"**Output:** `{result}`")
    elif method == 'startswith':
        prefix = st.text_input("Prefix to check for:", "")
        if prefix:
            result = user_input.startswith(prefix)
            st.write(f"**Output:** `{result}`")
    elif method == 'endswith':
        suffix = st.text_input("Suffix to check for:", "")
        if suffix:
            result = user_input.endswith(suffix)
            st.write(f"**Output:** `{result}`")
    elif method == 'isalpha':
        result = user_input.isalpha()
        st.write(f"**Output:** `{result}`")
    elif method == 'isnumeric':
        result = user_input.isnumeric()
        st.write(f"**Output:** `{result}`")
    elif method == 'isalnum':
        result = user_input.isalnum()
        st.write(f"**Output:** `{result}`")
    elif method == 'join':
        iterable_input = st.text_input("Enter strings to join, separated by commas:", "hello,world")
        if iterable_input:
            iterable = iterable_input.split(",")
            result = ", ".join(iterable)
            st.write(f"**Output:** `{result}`")