Implementation of standard C library and original functions

All original functions are in the 'ori' directory

char **ft_split(char const *str, char c)

Splitting a string
str: Target to split
c: split character
return value: Array of strings after splitting

char *ft_strjoin(char const *s1, char const *s2)

String concatenation
s1, s2: strings
return value: the concatenated string.

char *ft_strmapi(char const *s, char (*f)(unsigned int, char))

Add processing one character at a time
s: Target to process
f: Operation contents
return value: the string after processing

char *ft_strtrim(char const *s1, char const *set)

Eliminate the preceding and following characters
s1: Target
set: Target to eliminate
return value: the string after processing

char *ft_substr(char const *s, unsigned int start, size_t len)

Cut off a string
s: Target to cut
start: Start position of the string to be cut.
return value: the cut string

int ft_isintoverflow(const char *str)

Check that the number in the string does not overflow the int type.
str: The number in the string
return value: 1 if the number overflows

Output a string to the specified file descriptor.

Function for concatenated lists