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# ft\_strlcpy

**Objective**

The function `ft_strlcpy` replicates the behavior of `strlcpy`, a safer alternative to `strcpy`. It copies a string while ensuring null termination and avoiding buffer overflows.

### **Turn-in Requirements**

* **Directory:** `ex10/`
* **File:** `ft_strlcpy.c`
* **Allowed Functions:** None

### **Prototype**

```c
unsigned int ft_strlcpy(char *dest, char *src, unsigned int size);
```

***

### **Implementation**

```c
unsigned int	ft_strlcpy(char *dest, char *src, unsigned int size)
{
	unsigned int	i;
	unsigned int	src_len;

	src_len = 0;
	while (src[src_len]) // Calculate the length of src
		src_len++;

	if (size == 0) // If size is 0, return the length of src without modifying dest
		return (src_len);

	i = 0;
	while (src[i] && i < size - 1) // Copy characters from src to dest
	{
		dest[i] = src[i];
		i++;
	}
	dest[i] = '\0'; // Ensure null termination

	return (src_len);
}
```

***

### **Explanation**

#### **Input Parameters:**

1. `dest`: The destination buffer where the `src` string will be copied.
2. `src`: The source string to be copied.
3. `size`: The maximum number of characters to copy, including the null terminator.

#### **Processing Steps:**

1. **Calculate `src_len`**
   * The function first iterates through `src` to determine its length.
2. **Check if `size` is 0**
   * If `size == 0`, the function **returns the length of `src`** without modifying `dest`.
3. **Copy Characters from `src` to `dest`**
   * The function copies characters from `src` to `dest` **up to `size - 1`** to ensure there is space for the null terminator.
4. **Null-Termination**
   * After copying, the function appends `'\0'` to `dest` to prevent overflow.
5. **Return Value**
   * The function **returns the total length of `src`**, allowing the caller to determine if truncation occurred.

***

### **Example Usage**

```c
#include <stdio.h>

unsigned int ft_strlcpy(char *dest, char *src, unsigned int size);

int main()
{
    char dest[20];
    char *src = "Hello, 42Berlin!";
    unsigned int len;

    len = ft_strlcpy(dest, src, sizeof(dest));
    printf("Copied string: %s\n", dest);
    printf("Length of source: %u\n", len);

    return 0;
}
```

#### **Expected Output**

```yaml
string: Hello, 42Berlin!
Length of source: 17
```

***

### **Edge Cases Considered**

✅ **If `size == 0`**, `dest` is not modified, but the function still returns `src` length.\
✅ Handles cases where `size` is smaller than `src` to prevent buffer overflow.\
✅ Ensures proper null termination (`'\0'`) for safe string handling.

***

### **Complexity Analysis**

* **Time Complexity:** **O(n)** → The function iterates through `src` **twice** (once for length calculation, once for copying).
* **Space Complexity:** **O(1)** → The function operates **in place** without additional memory.


---

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