# ft\_strdup

### Subject

{% code overflow="wrap" %}

```
STRDUP(3) (simplified)

NAME
    strdup -- save a copy of a string
SYNOPSIS
    char *strdup(const char *s1);
DESCRIPTION
    The strdup() function allocates sufficient memory for a copy of the string s1, does the copy, and returns a pointer to it. The pointer may subsequently be used as an argument to the function free(3).
    If insufficient memory is available, NULL is returned and errno is set to ENOMEM.
```

{% endcode %}

### Understandable explanation

For once, the man is really clear on what the function does. So I don't think I need to explain it with more details.

### Hints

We have to use malloc for this since the returned value of this function must be 'freeable' with the free function.

{% code title="ft\_strdup.c" overflow="wrap" lineNumbers="true" %}

```c
char *ft_strdup(const char *s1)
{
    /* use malloc to allocate enough space for s1 
     * we will have to copy it completely
     * so we need enough space for it
     */
     /* loop over s1 and copy each character in the new string you
      * just allocated
      */
     /* return the allocated and copied string */
}
```

{% endcode %}

### Commented solution

<details>

<summary>ft_strdup</summary>

{% code title="ft\_strdup.c" overflow="wrap" lineNumbers="true" %}

```c
#include "libft.h"

char *ft_strdup(const char *s1)
{
    char *dest;
    size_t i;
    
    /* allocating enough memory for s1 + 1 character
     * for the NUL-terminating character
     */
    dest = (char *) malloc(ft_strlen(s1) + 1);
    if (!dest)
        return (NULL);
    i = 0;
    /* looping over the whole s1 string */
    while (s1[i])
    {
        /* copying the current s1 character into the same
         * position in the dest string we allocated above
         */
        dest[i] = s1[i];
        i++;
    }
    /* setting the NUL-terminating character */
    dest[i] = 0;
    /* finally, we return the newly created string */
    return (dest);
}
```

{% endcode %}

</details>


---

# Agent Instructions: Querying This Documentation

If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question.

Perform an HTTP GET request on the current page URL with the `ask` query parameter:

```
GET https://42-cursus.gitbook.io/guide/0-rank-00/libft/libc-functions/ft_strdup.md?ask=<question>
```

The question should be specific, self-contained, and written in natural language.
The response will contain a direct answer to the question and relevant excerpts and sources from the documentation.

Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.