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by Dinesh Thakur Category: Basic Of C Programming

If you construct a long program today and try to recall it after a few days, there is every possibility that you would have forgotten quite a few things and even what the program does or what a particular name stands for. Comments if included in a program help in recollection of different names, data values and other parameters.

 
by Dinesh Thakur Category: Basic Of C Programming

Escape sequences are basically control characters used for formatting the output. These are combinations of a backslash and a character in lowercase. We have already used "\n", which shifts the curser to the next line. Table lists the escape sequences defined in C language.

 
by Dinesh Thakur Category: Basic Of C Programming

(i) It is a structured high-level language and is highly portable to different platforms.

(ii) C is closest to assembly language and hence it is extremely efficient. Some programmers call it "high-level assembly language", although it is not a justified comment.

 
by Dinesh Thakur Category: Basic Of C Programming

We can read a string using the %s conversion specification in the scanf function. However, it has a limitation that the strings entered cannot contain spaces and tabs. To overcome this problem, the C standard library provides the gets function. It allows us to read a line of characters (including spaces and tabs) until the newline character is entered, i. e., the Enter key is pressed. A call to this function takes the following form:

 
by Dinesh Thakur Category: Basic Of C Programming

The standard C library provides several functions and macros for character 1/0. Here we consider the getchar and putchar macros. As these macros read or write a single character, they are typically used in a loop to read/write a sequence of characters.

 
by Dinesh Thakur Category: Basic Of C Programming

The C standard library provides the executable code and declarations for functionality provided in it. The executable code for the library is provided in separate files, usually in the lib directory, in the installation directory of the compiler. The library files in Turbo C/C++ are named *.LIB, whereas those in the MinGW compiler provided with Dev-C++ and Code :: Blocks are named lib*. a.

 
by Dinesh Thakur Category: Basic Of C Programming

BASIC stands for beginner's all-purpose symbolic instruction code, and is a computer programming language that was invented in 1964 at Dartmouth University by John G Kemeny and Thomas E Kurtz. BASIC has the advantage of English-like commands that are easier to understand and remember than those of most other languages. Even so, the latest versions of BASIC can do just about anything programming languages like C or Pascal can do.



 
by Dinesh Thakur Category: Basic Of C Programming

We have some compiler preprocessor commands. This includes various #include files. Then comes the main function. Some name can also be given to the main function. Then, we have the variable declarations used in the main code. Then we have sub-functions.

 
by Dinesh Thakur Category: Basic Of C Programming

There are many "languages" like, for example C, Fortran, PASCAL etc., that help us to convert an algorithm in to something that a computer can understand. We will focus here only on C programming So. let us start looking at how do we create a "C program".



 
by Dinesh Thakur Category: Basic Of C Programming

Martin Richards developed a high-level computer language called BCPL in the year 1967. The intention was to develop a language for writing an operating system (OS). As you know an OS is software which controls the various processes in a computer system. This language was later improved by Ken Thompson and he gave it a new name B. The basic ideas about some topics such as arrays, etc., which were later inherited by C were developed in BCPL and B. In those days, the development of computers was in infancy. One of the serious constraints experienced while developing the language B was the small computer memory available at that time.



 
by Dinesh Thakur Category: Basic Of C Programming

Another component common to C programs is the header file. This supplies information about the standard library functions. These files all end with the .h extension and are added to the program using the #include pre-processor directive. All C compilers use a pre-processor as their first phase of compilation to manipulate the code of the source file before it is compiled.



 
by Dinesh Thakur Category: Basic Of C Programming

The main role of header file is it is used to share information among various files.To put it brief, if we have several functions say 4 functions named as f1, f2, f3, f4 placed in file say sample.c and if all the functions want to get accessed each other all must be placed in the same file sample.c. 



 
by Dinesh Thakur Category: Basic Of C Programming

when we said that every language consists of keywords and that these keywords are only understandable by the people who speak the language.The same is with C; keywords are special words that have special meaning in the C language and are reserved by the language. That last sentence has significant meaning, so I will take about it a little later on.

 
by Dinesh Thakur Category: Type And Variables

To store signed integers, we need to reserve one bit for the sign of the integer. It is usual convention to use a 0 bit to indicate positive sign and a 1 bit to indicate a negative sign.

 
by Dinesh Thakur Category: Type And Variables

Macros are small functions (generally single line functions) which may be dealt with the help of preprocessor directive #define. Here, we shall discuss only the directive #define which is also used to define constants. A macro may or may not have parameters. An advantage of using a macro is that if a program involves a large number of the function calls of a small function the overburden of function calls can make the program inefficient; in case of macro, the code is substituted wherever the macro occurs. Thus, a programmer does not have to repeat the code again and again in the source code of the program while the function call is eliminated. However, a disadvantage of using macro is that data types are not included in the macro nor are these checked by the compiler. A few illustrations of macros are given below.

 
by Dinesh Thakur Category: Type And Variables

The field width and precision setting may be used for characters and strings as well. However, these have different meaning. See the following code:

 
by Dinesh Thakur Category: Type And Variables

In general, the sign is not displayed with positive values. However, if we desire to display the + sign, we may add it in the control string. If the display is desired to be left justified as well as with+ sign, add + or ++between the % sign and the conversion character; for example, the following code for integers.

 
by Dinesh Thakur Category: Type And Variables

Precision is specified by the number of digits after the decimal point for the outputs for float as well as double numbers. If precision is not specified, it would be according to the default setting in the computer which is generally 6 digits. The precision may be specified by a period(.) followed by a positive number equal to the number of digits desired. An illustration is given below.



 
by Dinesh Thakur Category: Type And Variables

Type casting or type conversion refers to change of type of variables or pointers or user-defined objects from one type to another type. The need for type conversion arises in some operations involving two operands of different types, or even of same type. The example given below illustrates this concept.

 
by Dinesh Thakur Category: Type And Variables

An object is a space in memory with a name or an identifier. The lifetime of an object is the storage duration of the object in a program, that is, lifetime is the portion of program execution during which the object exists with a constant address in the program and retains the last stored value. Three types of storage durations are defined in C, that is, automatic, static, and allocated.

 

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About Dinesh Thakur

Dinesh ThakurDinesh Thakur holds an B.SC (Computer Science), MCSE, MCDBA, CCNA, CCNP, A+, SCJP certifications. Dinesh authors the hugely popular blog. Where he writes how-to guides around Computer fundamental , computer software, Computer programming, and web apps. For any type of query or something that you think is missing, please feel free to Contact us.