ft_striteri

Subject

FT_STRITERI (simplified)

NAME
    ft_striteri -- apply a function to each character of a string (index specified)
SYNOPSIS
    void ft_striteri(char *s, void (*f)(unsigned int, char*));
DESCRIPTION
    Apply the function 'f' to each characters of the string 's', passing its index as a first parameter.
    Each character is transmitted by address to 'f' so it can be modified if necessary.

Understandable explanation

ft_striteri works the same way as ft_strmapi does, take a look at the explanation for ft_strmapi and then come back here.

The difference between ft_striteri and ft_strmapi is that ft_striteri doesn't return anything and works directly on the original string.

Hints

This functions takes two parameters, the first one is a string, and the second one is a function.

What ft_striteri does is apply the function f to every character of the string s.

It passes the index of the character in the string, and a pointer to the character to the function f.

The function f directly modifies the value of the character in the original string.

At the end, we don't need to return anything but the original string will have been modified.

Commented solution

ft_striteri

ft_striteri.c

#include "libft.h"

void ft_striteri(char *s, void (*f)(unsigned int, char*))
{
    unsigned int i;
    
    i = 0;
    /* looping over the whole original string */
    while (s[i])
    {
        /* apply the function f to the character at index i
         * passing i and the address to s[i] as parameter to f
         * f will update the original string directly
         */
        (*f)(i, &s[i]);
        i++;
    }
}