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# ft\_strupcase

**Objective:**

Create a function that transforms all lowercase letters in a string into uppercase letters. The function modifies the original string and returns it.

***

**Turn-in Requirements:**

* **Directory:** `ex07/`
* **File:** `ft_strupcase.c`
* **Allowed Functions:** None

***

**Prototype:**

```c
char *ft_strupcase(char *str);
```

***

**Implementation:**

Here’s the original implementation, followed by an optimized version:

**Code Implementation:**

```c
char *ft_strupcase(char *str)
{
    int i;

    i = 0;
    while (str[i] != '\0') // Loop through each character in the string
    {
        // If the character is a lowercase letter ('a' to 'z'), convert it to uppercase
        if (str[i] >= 'a' && str[i] <= 'z')
            str[i] -= 32; // Subtract 32 to convert lowercase to uppercase
        i++;
    }
    return (str); // Return the modified string
}
```

**Explanation:**

* **Input Parameter:**\
  The function takes a single parameter, `str`, which is a pointer to the first character of the string.
* **Conversion Logic:**
  * If a character is within the range `'a'` to `'z'`, subtracting the difference between `32`converts it to uppercase.
  * This transformation is done directly on the original string.
* **Return Value:**\
  The function returns the pointer to the modified string.

***

**Example Usage:**

```c
#include <stdio.h>

char *ft_strupcase(char *str);

int main()
{
    char str1[] = "hello world";
    char str2[] = "42Berlin";
    char str3[] = "";
    char str4[] = "AlreadyUpperCase";

    printf("%s\n", ft_strupcase(str1)); // Output: HELLO WORLD
    printf("%s\n", ft_strupcase(str2)); // Output: 42BERLIN
    printf("%s\n", ft_strupcase(str3)); // Output: (empty string)
    printf("%s\n", ft_strupcase(str4)); // Output: ALREADYUPPERCASE
    return 0;
}
```

***

**Explanation of Outputs:**

* `"hello world"`: All lowercase letters are converted to uppercase.
* `"42Berlin"`: Only the lowercase letters (`e`, `r`, `l`, `i`, `n`) are converted.
* `""`: The empty string remains unchanged.
* `"AlreadyUpperCase"`: The function leaves uppercase letters unchanged.

***

**Notes:**

* Remove or comment out the `main` function when submitting your code.
* Ensure your code adheres to the Norminette coding standards.
* This implementation is efficient, with an `O(n)` time complexity where `n` is the length of the string.


---

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