Simple string class in c++

SimpleString.cpp

#include<stdio.h>
#include<stdlib.h>
#include<string.h>
#include<ctype.h>

class SimpleString {
    public:
        SimpleString(const char* text) {
            raw_str = (char**)malloc((size_t)(sizeof(const char*) * strlen(text)));
            strcpy(*raw_str, text);
        }

    SimpleString operator = (const char* text) {
        *this = SimpleString(text);
        return *this;
    }

    SimpleString operator += (const char* text) {
        concat(text);
        return *this;
    }

    char* unwrap() {
        return *raw_str;
    }

    private:

    inline void resize(const char* new_str) {
        size_t size = sizeof(char*) * strlen(new_str);
        raw_str = (char**)realloc(raw_str, size);
        strcpy(*raw_str, new_str);
    }

    inline void concat(const char* new_str) {
        resize((const char*)strcat(*raw_str, new_str));
    }

    char** raw_str;
};