Answer : Option A

Explanation :

scanf is a function that reads data with specified format from a given string stream source. 
scanf("%d",&number);

atoi() convert string to integer. 
var number;
number = atoi("string");

Answer : Option A

Explanation :

string.h is the header in the C standard library for the C programming language which contains 

macro definitions, constants, and declarations of functions and types used not only for string 

handling but also various memory handling functions.

Answer : Option A

Explanation :

itoa() takes the integer input value input and converts it to a number in base radix. The resulting number a sequence of base-radix digits. Example:

 /* itoa() example */
#include<stdio.h>
#include <stdlib.h>

int main ()
{
	int no;
	char buff [50];
	printf ("Enter number: ");
	scanf ("%d",&no);
    
	itoa (no,buff,10);
	printf ("Decimal: %s\n",buff);
    
	itoa (no,buff,2);
	printf ("Binary: %s\n",buff);
    
	itoa (no,buff,16);
	printf ("Hexadecimal: %s\n",buff);
    
	return 0;
}   

Output:
Enter a number: 1250
Decimal: 1250
Binary: 10011100010
Hexadecimal: 4e2

Answer : Option B

Explanation :

The C standard library consists of a set of sections of the ISO C standard which describe 

a collection of header files and library routines used to implement common operations, 

such as input/output and string handling, in the C programming language. The C standard 

library is an interface standard described by a document; it is not an actual library of software 

routines available for linkage to C programs.

Answer : Option A

Explanation :

g = strcmp(s1, s2); returns 0 when the strings are equal, a negative integer when s1 is less than s2, or a positive integer if s1 is greater than s2, that strcmp() not only returns -1, 0 and +1, but also other negative or positive values(returns difference between the first non-matching pair of characters between s1 and s2). A possible implementation for strcmp() in "The Standard C Library".

int strcmp (const char * s1, const char * s2)
{                
    for(; *s1 == *s2; ++s1, ++s2) 
    {
        if(*s1 == 0)
            return 0;
    }
    return *(unsigned char *)s1 < *(unsigned char *)s2 ? -1 : 1;
}