Understanding and Using Pointers in Delphi

Understanding and Using Pointers in Delphi Even though pointers arent as important in Delphi as they are in C or C, theyre such a basic tool that almost anything having to do with programming must deal with pointers in some fashion. Its for that reason that you might read about how a string or object is really just a pointer, or that an event handler such as OnClick, is actually a pointer to a procedure. Pointer to Data Type Simply put, a pointer is a variable that holds the address of anything in memory. To concrete this definition, keep in mind that everything used by an application is stored somewhere in the computers memory. Because a pointer holds the address of another variable, its said to point to that variable. Most of the time, pointers in Delphi point to a specific type: variValue, j : integer;pIntValue : ^integer;beginiValue : 2001;pIntValue : iValue;...j: pIntValue^;end; The syntax to declare a pointer data type uses a caret (^). In the above code, iValue is an integer type variable and pIntValue is an integer type pointer. Since a pointer is nothing more than an address in memory, we must assign to it the location (address) of the value stored in the iValue integer variable. The operator returns the address of a variable (or a function or procedure as will be seen below). Equivalent to the operator is Addr function. Note that pIntValues value is not 2001. In this sample code, pIntValue is a typed integer pointer. Good programming style is to use typed pointers as much as you can. The Pointer data type is a generic pointer type; it represents a pointer to any data. Note that when ^ appears after a pointer variable, it de-references the pointer; that is, it returns the value stored at the memory address held by the pointer. In this example, variable j has the same value as iValue. It might look like this has no purpose when we can simply assign iValue to j, but this piece of code lies behind most calls to Win API. NILing Pointers Unassigned pointers are dangerous. Since pointers let us work directly with computers memory, if we try to (by mistake) write to a protected location in memory, we could get an access violation error. This is the reason we should always initialize a pointer to NIL. NIL is a special constant that can be assigned to any pointer. When nil is assigned to a pointer, the pointer doesn’t reference anything. Delphi presents, for example, an empty dynamic array or a long string as a nil pointer. Character Pointers The fundamental types PAnsiChar and PWideChar represent pointers to AnsiChar and WideChar values. The generic PChar represents a pointer to a Char variable. These character pointers are used to manipulate null-terminated strings. Think of a PChar as being a pointer to a null-terminated string or to the array that represents one. Pointers to Records When we define a record or other data type, its a common practice also to define a pointer to that type. This makes it easy to manipulate instances of the type without copying large blocks of memory. The ability to have pointers to records (and arrays) makes it much easier to set up complicated data structures as linked lists and trees. typepNextItem ^TLinkedListItemTLinkedListItem recordsName : String;iValue : Integer;NextItem : pNextItem;end; The idea behind linked lists is to give us the possibility to store the address to the next linked item in a list inside a NextItem record field. Pointers to records can also be used when storing custom data for every tree view item, for example. Procedural and Method Pointers Another important pointer concept in Delphi is procedure and method pointers. Pointers that point to the address of a procedure or function are called procedural pointers. Method pointers are similar to procedure pointers. However, instead of pointing to standalone procedures, they must point to class methods. Method pointer is a pointer that contains information about both the name and object thats being invoked. Pointers and Windows API The most common use for pointers in Delphi is interfacing to C and C code, which includes accessing the Windows API. Windows API functions use a number of data types that might be unfamiliar to the Delphi programmer. Most of the parameters in calling API functions are pointers to some data type. As stated above, we use null-terminated strings in Delphi when calling Windows API functions. In many cases, when an API call returns a value in a buffer or pointer to a data structure, these buffers and data structures must be allocated by the application before the API call is made. The SHBrowseForFolder Windows API function is one example. Pointer and Memory Allocation The real power of pointers comes from the ability to set aside memory while the program is executing. This piece of code should be enough to prove that working with pointers is not as hard as it might seem at first. Its used to change the text (caption) of the control with the Handle provided. procedure GetTextFromHandle(hWND: THandle) ;var pText : PChar; //a pointer to char (see above)TextLen : integer;begin{get the length of the text}TextLen:GetWindowTextLength(hWND) ;{alocate memory}GetMem(pText,TextLen) ; // takes a pointer{get the controls text}GetWindowText(hWND, pText, TextLen 1) ;{display the text}ShowMessage(String(pText)){free the memory}FreeMem(pText) ;end;

Reconsider Planting Leyland Cypress in Your Yard

Reconsider Planting Leyland Cypress in Your Yard The rapidly-growing Leyland cypress tree, or  Cupressocyparis leylandii,  quickly outgrows its space in a typical yard, unless properly and regularly trimmed. These trees have the potential to grow to 60 feet tall. They are not a practical tree to plant as a small yard hedge on tight, six- to eight-foot  centers. Tight spacing of the plant means that you must commit major time and effort to constant pruning. Leyland cypress is a  short-lived conifer, with a typical lifespan of 20 to 25 years, and will eventually have to be removed. Even properly-spaced trees left to grow may have limited root support, and are subject to being blown down during high winds if planted on wet soils. Consider the work needed to maintain a Leyland cypress before planting one. Why Not Plant Leyland Cypress? A study of Leyland cypress done at the University of Tennessee indicated that a lot of damage on these trees is simply environmental, and not always directly caused by a disease or insect. The study indicated that stress from a harsh winter can cause sporadic limb die off among Leyland cypress trees. Leyland cypresses grow into large, mature trees at 60-plus feet tall with a potential 20-plus foot spread. When they are planted as hedges on tight centers less of than 10 feet, there will be a major competitive  struggle for nutrients and shading. When needles turn brown or drop, the tree is reacting to environmental stresses. Leyland cypress trees do not tolerate many diseases and insects well, especially when environmental stressors are present. Spacing and soil may create an environment that can cause future stress on these trees. Planting Leyland cypress too close together or too close to other trees and structures that shade them can decrease vigor and increase pest damage. Caring for an Existing Tree Eliminating moisture stress on Leyland cypress through watering techniques can help lessen the occurrence of canker diseases. In particular, Leyland cypress is susceptible to Seiridium canker. There is no control for this disease other than to prune out the infected plant part. Watering is a long-term commitment for the Leyland cypress owner. These trees should be watered during any period of dry weather and should receive at least 1 inch of water per week. Pour the water at the base of the tree, and do not spray water on the foliage with sprinklers or watering techniques that can cause various  tree disease. As these tree age and lose lower foliage, consider removing Leyland cypress individually as they deteriorate, and replace each with a deciduous evergreen tree like wax myrtle.

Bodoni Typeface Research Paper Example | Topics and Well Written Essays - 250 words

Bodoni Typeface - Research Paper Example lopments and finally ended with the flat un bracketed typeface which were seen as extremely different from thick and thin strokes and contained a geometrical projection.The Bodoni and italics have been broadly used and have turned into a vital part of todays typographic gear, setting the stage in denoting the end of calligraphy and the begin of refined, sophisticated and organized printing. Surely, Giambattista Bodoni implied for his typefaces to be seen and read, and his endeavors were intended to be looked upon and acknowledged as show-stoppers instead of just correspondence (Clair 273). During the historical events, it was applied widely during the 18th century in the Italian books. Some computerized variants of Bodoni are said to be difficult to peruse because of "astonish" brought on by the exchanging thick and slender strokes, especially as the slim strokes are flimsy at little point sizes Clair (273). This happens when show adaptations are utilized at content sizes, and it is additionally valid for much show sort that is used at content sizes. Non-stunning renditions of Bodoni that are proposed to be used at content size are "Bodoni Old Face", upgraded for 9 focuses; ITC Bodoni 12 (for 12 centers); and ITC Bodoni 6 (for 6 focuses. Bodo has been applied in for a wide mixture of material, going from eighteenth-century Italian books to 1960s periodicals. It is also used in Hilton hotels on bar and menus within the hotels. During the 21century, the late way forms keep on being implemented as a part of publicizing while the early way forms are periodically utilized for fine book printing. Ted Hughes a UK Poet and Laureate also used Bodoni, during the periods of 1984–1998. In conclusion, currently the Typeface is not withstanding, in relation to the innovation accessibility digitally in this age. Bodoni is not simple to use (in the setting of pixels, eBooks, tablets et cetera) on account of its compelling differentiation in stroke weight and air transport

Edwin H. Sutherland Research Proposal Example | Topics and Well Written Essays - 1500 words

Edwin H. Sutherland - Research Proposal Example This essay is based upon one of the most celebrated criminologists of the twentieth-century and his theories: Edwin Sutherland. He was born August 13, 1883 in Gibbon, Nebraska and died in 1950. He grew up and studied in Ottawa, Kansas, and Grand Island, Nebraska. In 1904 he received the B.A degree from Grand Island College, and after that, he taught Latin, Greek, history, and shorthand for two years at Sioux Falls College in South Dakota. In 1906 he left Sioux Falls College and entered graduate school at the University of Chicago from which he received his doctorate. (Gaylord, 1988:7-12) There, he changed his major from history to Sociology. Much of his study was influenced by Chicago school's approach to the study of crime that emphasized human behavior as determined by social and physical environmental factors, rather than genetic or personal characteristics. After completing graduate studies he was employed at the University of Minnesota between 1926 and 1929 and solidified his reputation as one of the country's leading criminologists. During this period, his focus was on Sociology as a scientific enterprise whose goal was the understanding and control of social problems, including crime (Gaylord, 1988:13). Later he moved to Indiana University and became the founder of the Bloomington school of Criminology at Indiana University. During that time, he published 3 books, including Twenty Thousand Homeless Men (1936), The Professional Thief (1937), and the third edition of Principles of Criminology (1939). In 1939 he was elected president of the American Sociological Society, and in 1940 was elected president of the Sociological Research Association. According to him, "Criminology is the body of knowledge regarding delinquency and crime as a social phenomena. It includes within its scope the process of making laws, breaking laws, and of reacting toward the breaking of laws. These processes are three aspects of a somewhat unified sequence of interactions. The objective of Criminology is the development of a body of general and verified and principles and of other types of knowledge regarding this process of law, crime, and reaction to crime." (1974: 3) He was the first twentieth century criminologist to forcefully argue that criminal behavior was learned. His theory of differential association, developed in 1934 and 1947, was that persons who become criminal do so because of contacts with criminal patterns and isolations from non-criminal patterns. Differential association theory was Sutherland's major sociological contribution to Criminology; similar in importance to strain theory and social control theory. These theories all explain deviance in terms of the individual's social relationships. Sutherland's theory departs from the pathological perspective and biological perspective by attributing the cause of crime to the social context of individuals. "He rejected biological determinism and the extreme individualism of psychiatry, as well as economic explanations of crime. His search for an alternative understanding of crime led to the development of differential association theory. In contrast to both classical and biological theories, differential asso

Determining The Ratio Of Circumference To Diameter Of A Circle :: essays research papers

Determining the Ratio of Circumference to Diameter of a Circle   Ã‚  Ã‚  Ã‚  Ã‚  In determining the ratio of the circumference to the diameter I began by measuring the diameter of one of the si objects which contained circles, then using a string, I wrapped the string around the circle and compared the length of the string, which measured the circumference, to a meter stick. With this method I measured all of the six circles. After I had this data, I went back and rechecked the circumference with a tape measure, which allowed me to make a more accurate measure of the objects circumferences by taking away some of the error that mymethod of using a string created.   Ã‚  Ã‚  Ã‚  Ã‚  After I had the measurements I layed them out in a table. The objects that I measured were a small flask, a large flask, a tray from a scale, a roll of tape, a roll of paper towels, and a spraycan.   Ã‚  Ã‚  Ã‚  Ã‚  By dividing the circumference of the circle by the diameter I was able to calculate the experimental ratio, and I knew that the accepted ratio was pi. Then I put both ratios in the chart.   Ã‚  Ã‚  Ã‚  Ã‚  By subtracting the accepted ratio from the experimental you find the error. Error is the deviation of the experimental ratio from the accepted ratio. After I had the error I could go on to find the percentage error. The equation I used was, error divided by the accepted ratio times 100. For example, if I took the error of the experimental ratio for the paper towels, which was 0.12. I took that and divided it by the accepted ratio giving me .03821651. Then I multiplied that by 100 giving me about 3.14. Using these steps I found the percentage error for all of the objects measured.   Ã‚  Ã‚  Ã‚  Ã‚  The next step was to graph the results. I was able to do this very easily with spreadsheet. I typed in all of my data and the computer gave me a nice scatter block graph. I also made a graph by hand. I set up the scale by taking the number of blocks up the side of my graph and dividing them by the number of blocks across. I placed my points on my hand drawn graph. Once I did this I drew a line of best representation because some of the points were off a little bit due to error.   Ã‚  Ã‚  Ã‚  Ã‚  By looking at my graph I can tell that these numbers are directly proportional to each other. In this lab it was a good way to learn about error

Argumentative Essay Essay

For many years, the importance of English has increased because it has became a very common language all over the world. Owing to this situation, there are lots of argumentative topics which are about the power of English. One of them is about the medium of instruction at Turkish universities whether it should be English or not. First of all, the definition of the English as a medium of instruction can be made. Haagen – Schà ¼tzenhà ¶fer & Mathelitsch (n.d.) explain that, â€Å"English as a Medium of Instruction is a †¦ bilingual teaching – method. The main idea of EMI is to combine the conventional instruction of content – area subjects with †¦ a foreign language is used as a ‘tool’ for communication in different subjects† (p.1). In addition to this explanation, this type of education at Turkish universities can be very beneficial for students. Therefore, the medium of instruction should be English at universities in Turkey. Opponents of this argument claim that the English as a medium of education is not beneficial for students in some cases. They argue that this type of education causes two main problems which are misunderstanding problems and economical problems. Firstly, in Turkey, there is a common belief that if the educational language is English at universities, it can lead to not understanding of the courses very well due to the departmental technical jargons. For example, in engineering department, because of the English educational language, student may have some difficulties in their technical courses. However, this view is highly debatable. In the beginning of the university education, there is an English proficiency exam which tests the students’ level of English for being appropriate to the departmental technical courses. After this exam, for students who fail this exam, there is a preparatory year and the aim of this year is to prepare students their courses and to increase their level of English. Secondly, the opponents claim that, in English medium of universities, the fee of instruction can be a problem for poor students because it is higher than the other universities’. However this idea is open to debate. For poor students, there are lots of scholarship opportunities. Governments, universities and some big companies are ready to give some scholarship to poor students for rescuing them from their economical problems. Therefore, the high fee of  instruction is not a problem for poor students. English medium universities provide some advantages to students in some areas. Firstly, they are very useful for students in the most important field which is education. When the medium of education is English at universities, students have an ability to search in foreign sources. Therefore, their search area will expand and they can use the foreign sources in their researches. According to Economy Department of Istanbul University (n.d.), the English medium of instruction has lots of benefits for students. For example, in the English medium of instruction students get the chance to access and use the worldwide resources. Furthermore, this educational style makes it possible to enhance reading and comprehension skills and writing in English (p.1). Moreover, this educational style gives to students a chance to be educated in other countries. For example, many universities have Erasmus program which is the student exchange program between different countries’ universities. To ap ply this program the most important thing is knowing English. Due to the English medium universities, students already know English. Hence they have an opportunity to apply this program and to be educated in different countries. Secondly, English medium of instruction also provides some economical advantages to students. Thanks to the English medium of education, students do not have to spend any money to learn English. For instance, according to TOMER (n.d.) which is a famous and qualified foreign language course, the cost of the specific purpose foreign language courses is 576.00 TL. In addition to this, in this language course, there are speaking classes and their cost is also 350.00 TL (p.1). If the medium of instruction is English, students do not have to pay these high costs for learning English. Therefore, it gives an economical advantage to them. Furthermore, this educational style is useful for students when they find and apply a job. In Turkey, knowing English is very important quality for applying any job. Most companies want from their applicants to know English very well. If the medium of education is English, this increases the chance of finding a good job. Not only in educational and economical field, but also in social and business life, the English medium of education at universities is useful for  students. Firstly, in social life, it gives to students some advantages. For instance, students may gain a chance to live abroad because when they graduate from English medium of universities, their level of English will become high. Therefore, they will not any language problems when they live abroad. Furthermore, it is also beneficial in social relationships. If students know English, they have an opportunity to communicate and have friendship relation with foreign people or students. Hence, their social environment can expand. For example, at METU there are many foreign students and Turkish METU students have a chance to have foreign friends and communicate with foreign people. Secondly, this educational style has some advantages in business life. For instance, to work for international companies, English is very important because it is the common language in the world. If the graduates know their subjects in English very well, they automatically have a chance to work in these companies. Therefore, being a graduate from English medium of universities is a very significant advantage for students. Moreover, it gives to students an opportunity to have business life in foreign countries. For instance, lots of METU graduates maintain their business life in foreign countries. Being a graduate from METU whose educational language is English gives them to this chance. All in all, in Turkey, if the educational language is English at universities, students gain lots of benefits from it. These are about their education, economy, social, and business life. When these benefits are thought and examined carefully, the importance of English for students can be obviously seen. Because English is the today’s global language and it gives lots of advantages to students, the medium of instruction should be English at universities. REFERENCES Bà ¶là ¼mler: Ä °ngilizce Ä °ktisat: TanÄ ±tÄ ±m. (n.d.). Retrieved from http://www.istanbul.edu.tr/iktisat/bolumler.php Course fees. (n.d.). Retrieved from http://www.tomer.ankara.edu.tr/english/index.html# Haagen-Schà ¼tzenhà ¶fer, C. & Mathelitsch, L. (n.d.). English as a medium of instruction in science-teaching. Retrieved from http://www.fisica.uniud.it/girepseminar2001/CS06/HAAGEN_03_FINAL.pdf

Taking a Look at Queen Elizabeth I - 570 Words

She is the last Tudor monarch, and the only virgin queen in her bloodline. Elizabeth I of England was born on September 7, 1533 at Greenwich palace to Anne Boleyn and Henry VIII. After her sister, Mary I, died on November 17, 1558, Elizabeth came back from her arrest to claim the throne. She is known for being a cunning and shrewd survivalist. Since birth, her life has been about surviving all the odds against her. As she fights her way to the top, the economy, the country’s culture, science and technology, government, and communication will change all around her. Because of her family, Elizabeth was left with a crumbling economy. As each family member ruled, the collapsing economy would worsen, and it was up to Elizabeth to rebuild what her family destroyed. Henry VIII had changed the coinage so that the face value was less, and Mary I lost thousands of dollars to a war that England was not involved in yet. To undo what her family did, she not only taxed the common peo ple, but she taxed those with more riches as well. As she spoke with her financial advisor, Thomas Gresham, he had advised to change the coinage. From there, the queen melted down all coins with no real value, and had a coinage that was newly minted with precious metals. In addition, she changed the face of the coin from her sister to her. As they maintained the coinage’s new value, the economy slowly became stable. Not only did she have economic reforms, but she also has religious reforms. When sheShow MoreRelated Analysis of film Shakespeare in Love Essay1158 Words   |  5 Pagesthat even in the 21st century Elizabethan drama impacts its audience as it did in the 1500s. The film captured England and the important influence of Elizabeth I during the Renaissance period. Even though Queen Elizabeth didnt have a major role in the film, her characteristics were displayed through the main heroine, Lady Viola. Lady Viola and Elizabeth were both courageous, well-educated women of the upper class. Even though they were privileged in class, they were poor in love and acquired brokenRead MoreReview Of Hail The Virgin Queen Essay1514 Words   |  7 PagesHail The Virgin Queen Elizabeth, a film made in 1998 depicts the early years of the reign of Elizabeth I of England and her struggle of learning exactly what it means to be a woman in control of an entire nation. This film is a historical drama with as many ups, downs, twists, and turns one would expect in a film where the main character is considered one of the most esteemed women in history. Elizabeth, played by actress Cate Blanchett at a time when England was divided in deciding whether or notRead MoreA Kingdom Strange By Dr. James Horn1736 Words   |  7 Pagessupplies that they required, John White decided to take a trip back to England to request Queen Elizabeth the IV for the resources that they needed. White left his friends and family including his daughter and her baby, Virginia Dare, who was the first English child born in the New World back at the island. But at that point, sadly he didn’t know that this was the last time he was going to see them. The queen proposed an offer for his c harity to raise money for the colony by fighting in the war againstRead More Why the Spanish Armada Invaded Britain and Lost Essay1180 Words   |  5 PagesSpanish Armada Essay In this essay I am going to look at why the Spanish armada wanted to invade Britain and why they failed to do so, was it down to luck or were the British too smart for the Spanish. And was it all Englands glory? The Spanish wanted to invade England was mainly to turn England back into a catholic country, and to get Queen Elizabeth of the throne and to get a queen who was for the catholic monarch on the throne. However there are many other reasons: Firstly Philip II couldnRead MoreQueen Elizabeth: Golden Age1406 Words   |  6 PagesElizabeth’s Golden Age Elizabeth was Queen of England from 1558-1603. During that time England was a strong country and she was a successful queen. Many people thought Elizabeth would not last long without a powerful husband but they were proved wrong. In fact Elizabeth was very clever in not choosing a husband. She didn’t choose a husband because she didn’t want anybody taking over her throne. There were four men that she could have married but said no to. The first man was Philip of Spain. PhilipRead MoreThe Jewish People Of My Heritage1678 Words   |  7 Pagesthis Essay one must look at the personal importance of historical events and choose carefully to embody the choices being considered. Within the subjects that I have chosen for this Essay I am embarking to express my individual opinions and views on the following subjects. We will be going over the seedling of gender equality, the faith of the Jewish people of my heritage, the Greeks impact on architecture and design, the council that made a religion from a man, and lastly a Queen that inspires me toRead MoreThe Church Of England Was Only A Half R1225 Wor ds   |  5 PagesThis statement is valid to a considerable extent. This is due to the fact that before Elizabeth came to the throne her siblings had been before her, Edward VI (1547-53) and Mary I (1553-59), these two had a contrasting religious beliefs and both implemented harsh penalties for those who did not conform to their religious reform. This is one aspect of the Mid-Tudor crisis which then creates a problem for Elizabeth in enforcing religion successfully as Parliament now consisted of both Catholics andRead MoreEssay about Spanish Armada1365 Words   |  6 Pagesdeclared a war. One thing that made this war quite note worthy was the Spanish Armada, a fleet of 130-armed ship versus the well-trained navy of England. It is possible the world most famous naval battle and showed the true strength of England. This is a look into the causes, the war itself and the after affects on both countries. The Protestant Reformation had a huge impact on relationships between the European countries. Before Luther’s revolution shook up Europe, all those countries were united inRead MoreWorld War Two Essay1315 Words   |  6 Pagesbecoming more common and aggressive. The first thing I asked myself when I read this question was what first comes to mind when you think of war the worst war I know of. I immediately thought of my knowledge of World War Two. Today that is one of the most brutal things to look back on. Holocaust was incredibly brutal and inhuman. The things people endured are unimaginable. That was less than on hundred years ago and it doesn’t seem to be improving. I don’t think you can ever say war is ever humane.Read More Poetry Explication Essay1424 Words   |  6 Pagesthey have not, and even more astonishingly, look inside ones self and see what exists. If language is mixed with the tempo of music, something new arises; poetry is born. When words and ideas are set to a beat, they can far more subtly convey concepts that would otherwise need to be explicitly stated and the poem can be appreciated more as a whole, rather than as a collection of thoughts. Though I was never very interested in poetry in the past, taking classes in English has made me quite appreciative