Skip to main content

PROBLEM SOLVING AND PYTHON PROGRAMMING QUIZ

1) What is the first step in problem-solving? A) Writing code B) Debugging C) Understanding the problem D) Optimizing the solution Answer: C 2) Which of these is not a step in the problem-solving process? A) Algorithm development B) Problem analysis C) Random guessing D) Testing and debugging Answer: C 3) What is an algorithm? A) A high-level programming language B) A step-by-step procedure to solve a problem C) A flowchart D) A data structure Answer: B 4) Which of these is the simplest data structure for representing a sequence of elements? A) Dictionary B) List C) Set D) Tuple Answer: B 5) What does a flowchart represent? A) Errors in a program B) A graphical representation of an algorithm C) The final solution to a problem D) A set of Python modules Answer: B 6) What is pseudocode? A) Code written in Python B) Fake code written for fun C) An informal high-level description of an algorithm D) A tool for testing code Answer: C 7) Which of the following tools is NOT commonly used in pr...

Pointers to Pointers

Pointer to Pointers
In C, you can also use pointers that point to pointers. The pointers in turn point to data or even to other pointers. To declare pointers to pointers, just add an asterisk * for each level of reference.
          Fig: Pointer to Pointer
For example, consider the following code:
int x=10;
int *px, **ppx;
px = &x;
ppx = &px;
Let us assume, the memory locations of these variables are as shown in Fig.above
Now if we write,
printf("\n %d", **ppx);
Then, it would print 10, the value of x.

Drawbacks of Pointers
Although pointers are very useful in C, they are not free from limitations. If used incorrectly, pointers can lead to bugs that are difficult to unearth. For example, if you use a pointer to read a memory location but that pointer is pointing to an incorrect location, then you may end up reading 
a wrong value. An erroneous input always leads to an erroneous output. Thus however efficient your program code may be, the output will always be disastrous. Same is the case when writing a value to a particular memory location.
Let us try to find some common errors when using pointers.
int x, *px;
x=10;
*px = 20;
Error: Un-initialized pointer. px is pointing to an unknown memory location. Hence it willoverwrite that location’s contents and store 20 in it.
int x, *px;
x=10;
px = x;
Error: It should be px = &x;
int x=10, y=20, *px, *py;
px = &x, py = &y;
if(px<py) 
printf("\n x is less than y");
else
printf("\n y is less than x");
Error: It should be if(*px< *py)

Labels:

Popular posts from this blog

Introduction to C Programs

INTRODUCTION The programming language ‘C’ was developed by Dennis Ritchie in the early 1970s at Bell Laboratories. Although C was first developed for writing system software, today it has become such a famous language that a various of software programs are written using this language. The main advantage of using C for programming is that it can be easily used on different types of computers. Many other programming languages such as C++ and Java are also based on C which means that you will be able to learn them easily in the future. Today, C is mostly used with the UNIX operating system. Structure of a C program A C program contains one or more functions, where a function is defined as a group of statements that perform a well-defined task.The program defines the structure of a C program. The statements in a function are written in a logical series to perform a particular task. The most important function is the main() function and is a part of every C program. Rather, the execution o...
Read more

Performance

Performance ( Optional ) * The I/O system is a main factor in overall system performance, and can place heavy loads on other main components of the system ( interrupt handling, process switching, bus contention, memory access and CPU load for device drivers just to name a few. ) * Interrupt handling can be relatively costly ( slow ), which causes programmed I/O to be faster than interrupt driven I/O when the time spent busy waiting is not excessive. * Network traffic can also loads a heavy load on the system. Consider for example the sequence of events that occur when a single character is typed in a telnet session, as shown in figure( And the fact that a similar group of events must happen in reverse to echo back the character that was typed. ) Sun uses in-kernel threads for the telnet daemon, improving the supportable number of simultaneous telnet sessions from the hundreds to the thousands.   fig: Intercomputer communications. * Rather systems use front-end processor...
Read more

Mathematics

MATHEMATICS           Mathematics is the science that deals with shapes, quantities and arrangements. Archmedes is known as the father of Mathematics (287BC-212BC). Mathematics seek and use patterns to formulates new conjuctures.They resove truth or false by using mathematical proof. Mathematics developed by counting, calculation, Measurements, Shapes and motion of physical objects.  Definition Mathematics has no general accepted definition. Until 18th century Aristotle defined mathematics as "the science of quantity". Many mathematicans take no interest in definition they simply say "Mathematics is what Mathematican do". Three leading definition of mathematics today are logicist, intutionist, and formalist. Logicist - In terms of Benjamin peirce, the definition of mathematics in terms of logic are "the science that draws necessary conclusion" and also said that " All mathematics is symbolic logic" by Mathematician Rusell. Intutionist - L.E.J.Bro...
Read more