1. When is the right time to use :
a. Struct
b. Pointer
c. Function
d. Array
2. Write an Example That uses Combination of the above!
Answer:
a. A structure is another user defined data type available in C that allows to combine data items of different kinds.
Structures are used to represent a record. whenever we want to create a new data type, struct is the correct way to use.
b.A pointer is a variable whose value is the address of another
variable, i.e., direct address of the memory location. Like any variable
or constant, you must declare a pointer before using it to store any
variable address. whenever we want to change the value of a variable using the address,
pointer is the correct way to use.
c.A function is a group of statements that together perform a task. Every C program has at least one function, which is main(), and all the most trivial programs can define additional functions.whenever we want to create a certain instruction separated from the main() , function is the correct way to use.
d. An Array is a kind of data structure that can store a fixed-size sequential
collection of elements of the same type. An array is used to store a
collection of data, but it is often more useful to think of an array as a
collection of variables of the same type. whenever we want to create a storage of variable,
array is the correct way to use.
2.
and one with pointer :
source : www.tutorialspoint.com
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Sabtu, 05 Desember 2015
Minggu, 22 November 2015
stdarg.h in C
stdarg.h
is a header in the C standard library of the C programming language that allows functions to accept an indefinite number of arguments. It provides facilities for stepping through a list of function arguments of unknown number and type. C++ provides this functionality in the headercstdarg
.
- The contents of
stdarg.h
are typically used in variadic functions, though they may be used in other functions (for example,vprintf
) called by variadic functions.
- stdarg.h header defines a variable type va_list and three macros which can be used to get the arguments in a function when the number of arguments are not known i.e. variable number of arguments.
Library Variables
- va_list
Library Macros
This macro initializes ap variable to be used with the va_arg and va_end macros. The last_arg is the last known fixed argument being passed to the function i.e. the argument before the ellipsis. |
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Example :
more at :
https://en.wikipedia.org/wiki/Stdarg.h
http://www.tutorialspoint.com/c_standard_library/stdarg_h.htm
Sabtu, 21 November 2015
File in C
A File represents a sequence of bytes, regardless of it being a text
file or a binary file. C programming language provides access on high
level functions as well as low level (OS level) calls to handle file on
your storage devices.
How to Create a File
FILE *fileptr // File pointer called fileptr
fileptr = fopen()
Opening a File
use the fopen( ) function to create a new file or to open an existing file.
If you are going to handle binary files, then you will use the ones with 'b' in the above.
Example :
Since line 6 - 9 already create the file., if we delete line 6-9, it will still compile the same result, because the file is already saved
You can also use int fscanf(FILE *fp, const char *format, ...) function to read strings from a file, but it stops reading after encountering the first space character.
example :
more at :
http://www.tutorialspoint.com/cprogramming /c_file_io.htm
How to Create a File
FILE *fileptr // File pointer called fileptr
fileptr = fopen()
Opening a File
use the fopen( ) function to create a new file or to open an existing file.
FILE *fopen( const char * filename, const char * mode );
Here, filename is a string literal, which you will use to name your file, and access mode can have one of the following values −
r/rb | :Opens an existing text file for reading purpose. | |
w/wb | :Opens a text file for writing. If it does not exist, then a new file is created. Here your program will start writing content from the beginning of the file. | |
a/ab | ;Opens a text file for writing in appending mode. If it does not exist, then a new file is created. Here your program will start appending content in the existing file content. | |
r+/r+b | ;Opens a text file for both reading and writing. | |
w+/w+b | ;Opens a text file for both reading and writing. It first truncates the file to zero length if it exists, otherwise creates a file if it does not exist. | |
a+/a+b; | Opens a text file for both reading and writing. It creates the file if it does not exist. The reading will start from the beginning but writing can only be appended. |
Closing a File
To close a file, use the fclose( ) function. The prototype of this function is −int fclose( FILE *fp );
The fclose(-) function returns zero on success, or EOF if there is an error in closing the file.
Reading a File
int fgetc( FILE * fp );
The fgetc() function reads a character from the input file
referenced by fp. The return value is the character read, or in case of
any error, it returns EOF. The following function allows to read a string from a stream −char *fgets( char *buf, int n, FILE *fp );
The functions fgets() reads up to n-1 characters from the input stream referenced by fp. It copies the read string into the buffer buf, appending a null character to terminate the string.Example :
Since line 6 - 9 already create the file., if we delete line 6-9, it will still compile the same result, because the file is already saved
You can also use int fscanf(FILE *fp, const char *format, ...) function to read strings from a file, but it stops reading after encountering the first space character.
example :
more at :
http://www.tutorialspoint.com/cprogramming /c_file_io.htm
Kamis, 19 November 2015
Structures in C
Structure is another user defined data type available in C that allows to combine data items of different kinds.
To define a structure,
you must use the struct statement.
The struct statement defines a new data type, with more than one member.
The format of the struct statement is :
You can pass a structure as a function argument in the same way as you pass any other variable or pointer.
To define a structure,
you must use the struct statement.
The struct statement defines a new data type, with more than one member.
The format of the struct statement is :
struct [structure tag] { //*structure tag is optional member definition; member definition; ... member definition; } [one or more structure variables]; //*one or more structure variables also optional
And an Example of how to use Structure :
Structures as Function Arguments
You can pass a structure as a function argument in the same way as you pass any other variable or pointer.
and it can be simplified like this :
more at : www.tutorialspoint.com
Pointer & Reference in C
What is a Pointer ?
A Pointer is a variable whose value is the address of another variable, or direct address of the memory location. Like any variable or constant, you must declare a pointer before using it to store any variable address.
Format : type *var-name;
A Pointer is a variable whose value is the address of another variable, or direct address of the memory location. Like any variable or constant, you must declare a pointer before using it to store any variable address.
Format : type *var-name;
type is the pointer's base type; it must be a valid C data type
var-name is the name of the pointer variable.
The asterisk (*) used to declare a pointer
Example of a Valid format :
- int *ip; /* pointer to an integer */ - double *dp; /* pointer to a double */ - float *fp; /* pointer to a float */ - char *ch /* pointer to a character */
Example How To Use a Pointer:
Relation Between Pointer and Array
An array name is a constant pointer to the first element of the array.
Example :
Relation Between Pointer and Function
C programming allows passing a pointer to a function.
We just need to declare the function parameter as a pointer type.
here is an example where we pass a pointer to a function and change the value inside the function which reflects back in the calling function
source : www.tutorialspoint.com
Reference
Theres also one more kind of passing, called Passing By Reference
Basically, A reference is an alias for another variable
the syntax/ Format for this Reference is :
'type &variable' and it only works on c++ compiler
Heres what i learned For Example :
Minggu, 18 Oktober 2015
Arrays In C
- Array is a way to store variables in contingous space, that can be looped later
- Use Array when the number of inputs to be stored are too many
Look at the pic :
we can also write it this way :
To know the size of your Array, you can use function "sizeof" and divide it by one element of the array.
example :
Hope This Will Help
Peace !
Sabtu, 17 Oktober 2015
Recursion / Recursive Function in C
- Recursion is the process of repeating items in a self-similar way. Same applies in programming languages as well where if a programming allows you to call a function inside the same function that is called recursive call of the function as follows.
This program ends when we've counted to twenty, or more precisely, when count is
no longer less than twenty. This is a good base case because it means that if we
have an input greater than twenty, we'll stop immediately. If we'd chosen to
stop when count equaled twenty, then if the function were called with the input 21, it would run out of memory before stopping.
By the way, i wrote the function name as count_to_ten ., actually it should be count_to_twenty . but its just a name given by us, so i guess its okay. i forgot to modify that one
source :
Tutorialspoint : http://www.tutorialspoint.com/cprogramming/c_recursion.htm
Cprogramming : http://www.cprogramming.com/tutorial/c/lesson16.html
Hope this basic recursion example helps.
Peace!
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