PROBLEM SOLVING

PROBLEM SOLVING
Programming
To solve a computing problem, its solution must be specified in terms of sequence of
computational steps such that they are effectively solved by a human agent or by a digital
computer.
Programming Language
1) The specification of the sequence of computational steps in a particular
programming language is termedas a program
2) The task of developing programs is calledprogramming
3) The personengaged in programming activity is calledprogrammer
Techniques of Problem Solving
Problem solving an art in that it requires enormous intuitive power & a science for it
takes a pragmatic approach.
Here a rough outline of a general problem solving approach.
1) Write out the problem statement include information on what you are to solve &
consider why you needto solve the problem
2) Make sure you are solving the real problem as opposed to the perceived problem. To
checkto see that you define & solve the real problem
3) Draw & label a sketch. Define & name all variables and /or symbols. Show numerical
values of variables, if known.
4) Identify & Name
a. relevant principles, theories& equations
b. system & subsystems
c. dependent & independent variables
d. known & unknowns
e. inputs & outputs
f. necessaryinformation
5) List assumptions and approximations involved in solving the problem. Question the
assumptions and then state which ones are the most reasonable for your purposes.
6) Check to see if the problem is either under-specified, figure out how to find the
missing information. If over-specified, identify the extra information that is not
needed.
7) Relate problem to similar problem or experience
8) Use an algorithm

9) Evaluate and examine and evaluate the answer to see it makes sense.
Introductionto C Programming
C is a general-purpose computer programming language developed in 1972 by Dennis
Ritchie at the Bell Telephone Laboratories for use with the Unix operating system. C is a
structured programming language, which means that it allows you to develop programs using
well-defined control structures (you will learn about control structures in the articles to
come), and provides modularity (breaking the task into multiple sub tasks that are simple
enough to understand and to reuse).C is often called a middle-level language because it
combines the best elements of low-level or machine language with high-level languages.
Where is C useful?
C’s ability to communicate directly with hardware makes it a powerful choice for system
programmers. In fact, popular operating systems such as Unix and Linux are written entirely
in C. Additionally, even compilers and interpreters for other languages such as FORTRAN,
Pascal, and BASIC are written in C. However, C’s scope is not just limited to developing
system programs. It is also used to develop any kind of application, including complex
business ones. The followingis a partial list of areas where C language is used:
- Embedded Systems
- Systems Programming
- Artificial Intelligence
- Industrial Automation
- Computer Graphics
- Space Research
Why you shouldlearnC?
You should learnC because:
· C is simple.
· There are only 32 keywords so C is very easy to master. Keywords are words that have
special meaning in C language.

· C programs run faster than programs written in most other languages.
· C enables easy communication with computer hardware making it easy to write system
programs such as compilers andinterpreters.
WHY WE NEED DATA AND A PROGRAM
Any computer program has two entities to consider, the data, and the program. They are
highly dependent on one another and careful planning of both will lead to a well planned and
well written program. Unfortunately, it is not possible to study either completely without a
good working knowledge of the other. For that reason, this tutorial will jump back and forth
between teaching methods of program writing and methods of data definition. Simply follow
along and you will have a good understanding of both. Keep in mind that, even though it
seems expedient to sometimes jump right into coding the program, time spent planning the
data structures will be well spent and the quality of the final program will reflect the original
planning
How to run a simple c program
1. Copy Turbo c/c++ incomputer
2. Open c:tcbintc.axe
3. A window appears
4. Select File->newto opena new file
5. Type the followingprogram on editor
#include
void main()
{
print f(“hello”);
}

6. compile the program by pressingALT+F9
7. Run the program by pressingCTRL +F9
Note:
1. C is case sensitive
2. Always terminate statementswithsemicolon.
3. A program starts with main()
Explanationofprogram
#include is known as compiler directive. A compiler directive is a command to compiler to
translate the program in a certain way. These statement are not converted into machine
language but only perform some othertask.
main() is a function which the staring point for compiler to start compilation. So a function
must containa main() function.
DETECTION AND CORRECTION OF ERRORS
Syntactic errors and execution errors usually result in the generation of error messages when
compiling or executing a program. Error of this type is usually quite easy to find and correct.
There are some logical errors that can be very difficult to detect. Since the output resulting
from a logically incorrect program may appear to be error free. Logical errors are often hard
to find, so in order to find and correct errors of this type is known as logical debugging. To
detect errors test a new program with data that will give a known answer. If the correct
results are not obtained then the program obviously contains errors even if the correct results
are obtained.
Computer Applications: However you cannot be sure that the program is error free, since
some errors cause incorrect result only under certain circumstances. Therefore a new
program should receive thorough testing before it is considered to be debugged. Once it has
been established that a program contains a logical error, some ingenuity may be required to
find the error. Error detection should always begin with a thorough review of each logical
group of statements within the program. If the error cannot be found, it sometimes helps to
set the program aside for a while. If an error cannot be located simply by inspection, the

program should be modified to print out certain intermediate results and then be rerun. This
technique is referred to as tracing. The source of error will often become evident once these
intermediate calculations have been carefully examined. The greater the amount of
intermediate output, the more likely the chances of pointing the source of errors. Sometimes
an error simply cannot be located. Some C compilers include a debugger, which is a special
program that facilitates the detection of errors in C programs. In particular a debugger allows
the execution of a source program to be suspended at designated places, called break points,
revealing the values assigned to the program variables and array elements at the time
execution stops. Some debuggers also allow a program to execute continuously until some
specified error condition has occurred. By examining the values assigned to the variables at
the break points, it is easier to determine whenand where an error originates.
Linear Programming
Linear program is a method for straightforward programming in a sequential manner. This
type of programming does not involve any decision making. General model of these linear
programs is:
1. Read a data value
2. Computer an intermediate result
3. Use the intermediate result to computer the desiredanswer
4. Print the answer
5. Stop
StructuredProgramming
Structured programming (sometimes known as modular programming) is a subset of procedural
programming that enforces a logical structure on the program being written to make it more
efficient and easier to understand and modify. Certain languages such as Ada, Pascal, and BASE
are designed with features that encourage or enforce a logical program structure.
Structured programming frequently employs a top-down design model, in which developers map
out the overall program structure into separate subsections. A defined function or set of similar
functions is coded in a separate module or sub module, which means that code can be loaded into
memory more efficiently and that modules can be reused in other programs. After a module has
been tested individually, it is then integrated with other modules into the overall program
structure.
Advantages of StructuredProgramming

1. Easy to write:
Modular design increases the programmer's productivity by allowing them to look at
the big picture first and focus on details later.Several Programmers can work on a
single, large program, each working on a different module. Studies show structured
programs take less time to write than standard programs. Procedures written for one
program can be reused in other programs requiring the same task. A procedure that
can be used in many programs is said to be reusable.
2. Easy to debug:
Since each procedure is specialized to perform just one task, a procedure can be
checked individually. Older unstructured programs consist of a sequence of
instructions that are not grouped for specific tasks. The logic of such programs is
clutteredwithdetails and therefore difficultto follow.
3. Easy to Understand:
The relationship between the procedures shows the modular design of the program.
Meaningful procedure names and clear documentation identify the task performed by
each module. Meaningful variable names help the programmer identify the purpose of
each variable.
4. Easy to Change:
Since a correctly written structured program is self-documenting, it can be easily
understoodby another programmer.
StructuredProgramming Constructs
It uses only three constructs -
· Sequence (statements, blocks)
· Selection(if, switch)
· Iteration(loops like while and for)
Sequence
· Any valid expressionterminatedbya semicolonis a statement.
· Statements may be grouped together by surrounding them with a pair of curlybraces.
· Such a group is syntactically equivalent to one statement and can be inserted where
ever
· One statement is legal.
Selection

The selection constructs allow us to follow different paths in different situations. We
may also think of them as enabling us to express decisions.
The main selectionconstructis:
if (expression)
statement1
else
statement2
statement1 is executed if and only if expression evaluates to some non-zero number. If
expression evaluates to 0, statement1 is not executed. Inthat case, statement2 is executed.
If and else are independent constructs, in that if can occur without else (but not the
reverse)Any else is paired with the most recent else-less if, unless curly braces enforce a
different scheme. Note that only curly braces, not parentheses, must be used to enforce the
pairing. Parentheses
Iteration
Looping is a way by which we can execute any some set of statements more than one times
continuously.In C there are mainly three types of loops are used :
· while Loop
· do while Loop
· For Loop
The control structuresare easyto use because of the followingreasons:
1) They are easyto recognize
2) They are simple to deal with as they have just one entry and one exit point
3) They are free of the complications of anyparticular programming language

PROBLEM SOLVING

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