> For the complete documentation index, see [llms.txt](https://42-guide.gitbook.io/42-guide/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://42-guide.gitbook.io/42-guide/piscine-life/c04/ft_putstr.md).

# ft\_putstr

**Objective:**

Create a function that displays a string of characters on the standard output.

***

**Turn-in Directory:**

`ex01/`

***

**Files to Turn In:**

`ft_putstr.c`

***

**Allowed Functions:**

`write`

***

**Prototype:**

```c
void ft_putstr(char *str);
```

***

#### **Detailed Explanation**

The `ft_putstr` function takes a string `str` as input and displays it character by character on the standard output using the `write` function. It uses a helper function `ft_putchar` to print each character.

***

#### **Code Implementation**

```c
void ft_putchar(char c)
{
    write(1, &c, 1);  // Write the character 'c' to the standard output
}

void ft_putstr(char *str)
{
    int c;

    c = 0;
    while (str[c] != '\0')  // Loop through the string until the null terminator is found
    {
        ft_putchar(str[c]);  // Print the current character
        c++;  // Move to the next character
    }
}
```

***

#### **Example Usage**

```c
#include <unistd.h>

void ft_putstr(char *str);

int main(void)
{
    ft_putstr("Hello, 42!\n");  // Output: Hello, 42!
    ft_putstr("C programming is fun!\n");  // Output: C programming is fun!
    ft_putstr("");  // Output: (nothing, empty string)
    return 0;
}
```

***

#### **Edge Cases to Consider**

1. **Empty String**:
   * `""` → Prints nothing.
2. **String with Spaces**:
   * `"hello world"` → Prints `hello world`.
3. **String with Special Characters**:
   * `"hello\nworld"` → Prints `hello` followed by a newline and `world`.
4. **String with Null Terminator in the Middle**:
   * `"hello\0world"` → Prints `hello` (stops at the first null terminator).

***

#### **Limitations of ft\_putstr**

1. **No Bounds Checking**:
   * If given a non-null-terminated string, the function may lead to **undefined behavior**.
2. **No Handling of Non-String Input**:
   * If the input is not a valid string (e.g., a random memory address), the function will not work as expected.

***

#### **How It Works**

1. **Helper Function: `ft_putchar`**:
   * This function takes a single character `c` and writes it to the standard output using the `write` system call.
   * `write(1, &c, 1)` writes 1 byte (the character `c`) to file descriptor `1` (standard output).
2. **Main Function: `ft_putstr`**:
   * The function initializes a counter `c` to `0`.
   * It loops through the string `str` until it reaches the null terminator (`\0`).
   * For each character, it calls `ft_putchar` to print the character.
   * The counter `c` is incremented to move to the next character.

***

#### **Key Points to Remember**

1. **Null Terminator (`\0`)**:
   * The loop stops when it encounters the null terminator in the string.
2. **Efficiency**:
   * This implementation is efficient because it only requires a single loop through the string.
   * The time complexity is **O(n)**, where `n` is the length of the string.
3. **Edge Cases**:
   * If the string is empty (i.e., `""`), the function will print nothing because the loop won’t execute (the first character is `\0`).

***

#### **Best Practices**

1. **Adhere to the Norm**:
   * Ensure your code follows the **norminette** guidelines (e.g., no more than 25 lines per function, proper indentation, etc.).
   * Run `norminette` on your file to check for compliance.
2. **Test Edge Cases**:
   * Test your function with an empty string (`""`).
   * Test it with a string that contains only the null terminator (`"\0"`).
3. **Avoid Using Library Functions**:
   * Do not use built-in functions like `printf` or `puts` from the C standard library. The goal is to implement the functionality yourself.


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