11. How is fopen()used ?
Ans: The function fopen() returns a file pointer. Hence a file pointer is declared and it is assigned
as

FILE *fp;

fp= fopen(filename,mode);

filename is a string representing the name of the file and the mode represents:

“r” for read operation

“w” for write operation

“a” for append operation

“r+”,”w+”,”a+” for update operation

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12. Differentiate between a constant pointer and pointer to a constant?
Ans:

const char *p; //pointer to a const character.

char const *p; //pointer to a const character.

char * const p; //const pointer to a char variable.

const char * const p; // const pointer to a const character.

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13. Are the expressions *ptr ++ and ++ *ptr same?
Ans: No,*ptr ++ increments pointer and not the value pointed by it. Whereas ++ *ptr

increments the value being pointed to by ptr.

14. What’s the difference between these two declarations?
Ans: struct x1 { … };

typedef struct { … } x2;

The first form declares a structure tag; the second declares a typedef. The main difference is that the second declaration is of a slightly more abstract type.its users don’t necessarily know that it is a structure, and the keyword struct is not used when declaring instances of it.

15. What do the functions atoi(), itoa() and gcvt() do?
Ans:

atoi() is a macro that converts integer to character.

itoa() It converts an integer to string

gcvt() It converts a floating point number to string

16. Can a Structure contain a Pointer to itself?

Ans: Yes such structures are called self-referential structures.

17.Write a program which uses Command Line Arguments?
Ans:

#include

void main(int argc,char *argv[])

{

int i;

clrscr();

for(i=0;i

printf(“\n%d”,argv[i]);

}

18. Difference between syntax vs logical error?
Ans:

Syntax Error 

1-These involves validation of syntax of language.

2-compiler prints diagnostic message.

Logical Error

1-logical error are caused by an incorrect algorithm or by a statement mistyped in such a way

that it doesn’t violet syntax of language.

2-difficult to find.

19. What is a preprocessor, what are the advantages of preprocessor?
Ans: A preprocessor processes the source code program before it passes through the compiler.

1- a preprocessor involves the readability of program

2- It facilitates easier modification

3- It helps in writing portable programs

4- It enables easier debugging

5- It enables testing a part of program

6- It helps in developing generalized program

20. what are the types of file?( IMP)
Ans: Files are of two types

1-high level files (stream oriented files) :These files are accessed using library functions

2-low level files(system oriented files) :These files are accessed using system calls

90. Can we use any name in place of argv and argc as command line arguments ?

Ans: yes we can use any user defined name in place of argc and argv;

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