Count Uppercase, Lowercase Letters in C, C++, Java & Python – Code with Explanation & Examples in Short and Simple

   

C Program

void countCase(char *s) {
    int u = 0, l = 0;
    while (*s) {
        if (*s >= 'A' && *s <= 'Z') u++;
        else if (*s >= 'a' && *s <= 'z') l++;
        s++;
    }
    printf("Upper: %d\nLower: %d", u, l);
}

C Output

Upper: 5  
Lower: 5

C++ Program

void countCase(string s) { int u = 0, l = 0; for (char c : s) { if (isupper(c)) u++; else if (islower(c)) l++; } cout << "Upper: " << u << "\nLower: " << l; }

C++ Output

Upper: 5  
Lower: 4

JAVA Program

void countCase(String s) {
    int u = 0, l = 0;
    for (char c : s.toCharArray()) {
        if (Character.isUpperCase(c)) u++;
        else if (Character.isLowerCase(c)) l++;
    }
    System.out.println("Upper: " + u + "\nLower: " + l);
}

JAVA Output

Upper: 2  
Lower: 10

Python Program

def count_case(s):
    u = sum(1 for c in s if c.isupper())
    l = sum(1 for c in s if c.islower())
    print("Upper:", u, "\nLower:", l)

Python Output

Upper: 3  
Lower: 3

In-Depth Explanation

Example

Suppose the input is "HeLLoWorld".

Traversing the string, we:

Count 'H', 'L', 'L', 'W' and 'D' as upper case → 5

Count 'e', 'o', 'o', 'r' and 'l' as lower case → 5

We get a balanced case string — handy when checking text format or normalizing inputs.

Real-Life Analogy

Suppose you're looking at names typed in a form. Some individuals can type "john", some "JOHN", and others "John". You might need to ensure the number of uppercase vs lowercase characters to:

Check for proper formatting (e.g., title case)

Enforce consistent naming conventions

Prevent yelling (ALL CAPS) in user interfaces

This verification is typically performed during form validation, user input sanitization, or even data normalization operations.

Why It Matters

This trivial character categorization task illustrates how to:

Traverse strings

Use conditional checks (isupper, islower)

Keep independent counts depending on the character type

It also introduces some basic character processing, which is the foundation of most string algorithms — including encryption, formatting, and parsing.

Understanding how to process and separate cases is important when:

Sorting strings

Processing passwords

Normalizing user input

What You Learn from This

How to detect character types using ASCII values or built-in functions

Practical application of counters and conditions

Real-world significance of character-level data cleaning

Base for more complex string tasks such as case conversion, validation, or formatting

These are minor but fundamental skills required in data cleansing, text analytics, and input management systems.

Interview Relevance and Real Projects

This task is commonly employed during interviews to test:

String traversing capability

Knowledge of character handling

Clean conditional logic

It is also likely to be blended with:

Digit count

Special character count

Word classification logic

In real-life apps, this logic is encountered in:

Input validation forms (e.g., name fields)

Password strength testers (at least 1 uppercase & 1 lowercase needed)

Chat filters and text formatters

SEO-Optimized Explanation

Enumerating uppercase and lowercase characters in a string with C, C++, Java, and Python is a simple but useful exercise that enhances your character-processing logic. This program illustrates how to recognize alphabet case with loops or intrinsic functions and enumerate them separately. It is widely applied in form validation, input sanitizing, and password policy checks. Understanding how to verify the presence of uppercase and lowercase letters equips you with skills that are relevant to coding interviews, enhances your reasoning for text preprocessing in actual applications, and enables you to develop strong foundations in string manipulation. Such an exercise is crucial in system-level programming as well as front-end user data management.