Simply allocate a buffer to store the binary data in, and set a variable with the buffer size, and call the b58tobin function: bool b58tobin(void *bin, size_t *binsz, const char *b58, size_t b58sz)
note that a true zero-length base58 string is not supported here.

Allocate a string to store the base58 content, create a size_t variable with the size of that allocation, and call: bool b58enc(char *b58, size_t *b58sz, const void *data, size_t binsz) Note that you must pass a pointer to the string size variable, not the size itself. When b58enc returns, the variable will be modified to contain the actual number of bytes used (including the null terminator). If encoding fails for any reason, or if the string buffer is not large enough for the result, b58enc will return false. Otherwise, it returns true to indicate success.

check stuff is not really needed by anyone

works in any os with gcc/clang. it will not work with args which bump internals or out vars out of LONG_MAX and/or SIZE_MAX.

only for devices with LSB memory model

linux test:

c++ tb.cpp base58_c.cpp -o c
./c

sample code:

#include <iostream>
#include <iomanip>
#include "libbase58.h"

int main()
{
	
	char *t = new char[1000]();
	size_t c = 1000;
	const unsigned char b[19] = "uiyiuiuyijiojijjio";  /* last byte is '\0' coz of b[] dealt with by compiler. 
(size_t)sizeof(b) - 1 as last arg removes it from source binary block. */   
	b58enc(t, &c, (void *)b, (size_t)sizeof(b));
	
	std::cout << t << std::endl;
	unsigned char bc[250] = {};
	size_t wq = 250;
	bool c5 = b58tobin((void *)bc, &wq, t, strlen(t));
	c5 = b58tobin((void *)bc, &wq, t, strlen(t));
	
	std::cout << bc << std::endl << std::endl << wq ;
}

b:

7569796975697579696a696f6a696a6a696f00

t:

NVhHMCyXNHYRYg5mXw2nSnkLBh

base58.hpp

b58encode(std::string bytes)
input : raw bytes
output : std::pair with error code in .first and std::string with encoded stuff in .second