Use of getchar() and problem with New Line character

Hi all,
          i came across this problem when i was trying to code sorting of strings posted in happycodingc.blogspot.com...
Scenario:
                In the first occurence of scanf()when we enter data to it we tap ENTER key ,and this remains in the STDIN,when we encounter the progressive input functions like Scanf ,fgetc and fgets, then the input to it will be a NEWLINE character as the value in the STDIN is still unread and when the second input function tries to read from the STDIN and it will read '\n' due to enter key and this is not expected...sp we can avoid this by using getchar()in and fflush(stdin)in c++.
check the example
also try uncommenting the getchar();
int main()
{
    int iTest;
    char cTest;
    scanf("%d",&iTest);
  //  getchar();       
    scanf("%c",&cTest);
}

Naming Conventions To Be Used While Coding(Exclusively for Win32 programming)

The following table lists common prefixes.

Prefix	Description
a	Array
b	BOOL (int)
c	Char
cb	Count of bytes
cr	Color reference value
cx	Count of x (short)
dw	DWORD (unsigned long)
f	Flags (usually multiple bit values)
fn	Function
g_	Global
h	Handle
i	Integer
l	Long
lp	Long pointer
m_	Data member of a class
n	Short int
p	Pointer
s	String
sz	Zero terminated String
tm	Text metric
u	Unsigned int
ul	Unsigned long (ULONG)
w	WORD (unsigned short)
x,y	x , y coordinates (short)

These are often combined, as in the following.

Prefix combination	Description
pszMyString	A pointer to a string.
m_pszMyString	A pointer to a string that is a data member of a class.

Other conventions are listed in the following table.

Convention	Description
CMyClass	Prefix 'C' for C++ class names.
COMyObjectClass	Prefix 'CO' for COM object class names.
CFMyClassFactory	Prefix 'CF' for COM class factory names.
IMyInterface	Prefix 'I' for COM interface class names.
CImpIMyInterface	Prefix 'CImpI' for COM interface implementation classes.

SCANF_S its use....

Hi all,

     while i was coding for a program on Visual studio 2008 , ijust came across a warning C4996: 'scanf': This function or variable may be unsafe. Consider using scanf_s instead. To disable deprecation, use _CRT_SECURE_NO_WARNINGS.

                    Basically scanf_s is more secure. C does no type checking for you, so when you use scanf, C doesn't make sure that what the user inputs will fit in the variable that you've designated. For example, if you use this code,

char name[10]; //declares an array that can hold 10 characters
scanf("%s", name); //gets a string from the user and puts it in name

this will work fine if the user's name is  something smaller than 9 characters (9 because the last character is a terminator), but if the user's name is 10 or more characters, scanf starts writing into memory that doesn't belong to name. C won't catch this or warn you, so you won't find out until something else tries to use that memory and your program crashes.

Because this is such a common issue, scanf_s checks that the user input will fit in the given memory space, so many problems are avoided.


hence using scanf_s(); is a better way to be used


NOTE:WHILE CODING TRY TO SOLVE ALL THE WARNINGS FOR BETTER PRACTICES...

sizeof() Compile time operator

Hi all,

            I am just sharing a small Info on C Trap which I came across yesterday……may be most of u will be familiar with it…but I am jus explaining my experience…

           Scenario:

                          Char *ptr = (char*)malloc(sizeof(char)*30);

                           MyFunc(ptr);

         

                           Void  MyFunc(char *ptr)

{

Int I = sizeof(ptr);  gave me 4 bytes(as ptr is a pointer I mean its storing the address);;;I expected to return entire size allocated USING MALLOC.

I=sizeof(*ptr)   ; gave me 1byte(as the value stored in the address pointed by ptr was char type)

}

 So here ez my list of learnings;

     Actually I used sizeof(ptr); to get the entire memory allocated in main function…but It couldnot be done as sizeof() operator is a compile time operator,and the memory was allocated during runtime.

But after browsing thru net and asking few experienced guys I came to know that it’s the c Limitation in using memory and few latest compilers use some extra memory to keep track of size,datatype,and startpointer..

That is the reason why memset,memcpy fgets will use a 3^rd parmemter to store the size of the destination string……

Happycoding

Avinash