Change decimal numbers into binary format

Binary_Converter.c

char *stradd(const char *a, const char *b){
    size_t len = strlen(a) + strlen(b);
    char *ret = (char *)malloc(len * sizeof(char) + 1);
    return strcat(strcat(ret, a), b);
}
 
char *binaryConverter(int input_number) {
    int number = input_number;
    char *binaryString = (char *)malloc(sizeof(char));
    
    while (number != 0 ) {
        int remainder = number % 2;
        number = number/2;
        
        char *remainderChar = (char *)malloc(sizeof(char));
        sprintf(remainderChar, "%d", remainder);
        binaryString = stradd(remainderChar, binaryString);
        free(remainderChar);
    }
    
    return binaryString;
}
 
int main(int argc, const char * argv[]) {
    int number = 253;
    char *result = binaryConverter(number);
    printf("Your binary code: %s", result);
 
    return 0;
}