Storage Classes

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Storage Classes

Q

What are the different storage classes in C?

✍: FYIcenter

A

C has three types of storage: automatic, static and allocated.

Variable having block scope and without static specifier have automatic storage duration.

Variables with block scope, and with static specifier have static scope. Global variables (i.e, file scope) with or without the the static specifier also have static scope.

Memory obtained from calls to malloc(), alloc() or realloc() belongs to allocated storage class.

2007-02-26, 6107👍, 0💬

Bitwise Operations
Which bit wise operator is suitable for checking whether a particular bit is on or off? The bitwise AND operator. Here is an example: enum { KBit1 = 0x00000001 KBit2 = 0x00000010, KBit3 = 0x00000100, ... }; if ( some_int & KBit24 ) printf("Bit number 24 is ON\n"); else printf("Bit number 24 is O... 2007-02-26, 6889👍, 0💬

Macro vs. Function
Advantages of a macro over a function? Macro gets to see the Compilation environment, so it can expand __DATE__ __TIME__ __FILE__ #defines. It is expanded by the preprocessor. For example, you can't do this without macros. #define PRINT(EXPR) printf( #EXPR "=%d\n", EXPR) PRINT( 5+6*7 ) // expands in... 2007-02-26, 6639👍, 0💬

What does static variable mean
What does static variable mean? There are 3 main uses for static variables: If you declare within a function, it retains the value between function calls. If it is declared for a function name, by default function is extern. So it will be visible from other files. If the function declaration is as s... 2007-02-26, 6299👍, 0💬

Bitwise Operations
Which bit wise operator is suitable for turning on a particular bit in a number? The bitwise OR operator. In the following code snippet, the bit number 24 is turned ON: enum { KBit1 = 0x00000001 KBit2 = 0x00000010, KBit3 = 0x00000100, ... }; some_int = some_int | KBit24; 2007-02-26, 6265👍, 0💬

Storage Classes
What are the different storage classes in C? C has three types of storage: automatic, static and allocated. Variable having block scope and without static specifier have automatic storage duration. Variables with block scope, and with static specifier have static scope. Global variables (i.e, file s... 2007-02-26, 6108👍, 0💬

Strings vs. Character Arrays
What is the difference between strings and character arrays? A major difference is: string will have static storage duration, whereas as a character array will not, unless it is explicity specified by using the static keyword. Actually, a string is a character array with following properties: * the ... 2007-02-26, 5982👍, 0💬

Conditional Statements
What will happen in these three cases? if (a=0) { //somecode } if (a==0) { //do something } if (a===0) { //do something } 2007-02-26, 5835👍, 0💬

Variable Types
What are the types of variables x, y, y and u defined in the following code? #define Atype int* typedef int *p; p x, z; Atype y, u; Answer: x and z are pointers to int. y is a pointer to int but u is just an integer variable 2007-02-26, 5824👍, 0💬

Shift Operations
What will the following piece of code do? int f(unsigned int x) { int i; for (i=0; x!=0; x>>1) { if (x & 0x1) i++; } return i; } Answer: returns the number of ones in the input parameter X. 2007-02-26, 5823👍, 0💬

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