How to write your own sizeof operator?
#define my_sizeof(type) (char *)(&type+1)-(char*)(&type)
How will you print numbers from 1 to 100 without using loop?
We can use recursion for this purpose.
/* Prints numbers from 1 to n */
void printNos(unsigned int n)
{
if(n > 0)
{
printNos(n-1);
printf("%d ", n);
}
}
What is volatile keyword?
The volatile keyword is intended to prevent the compiler from applying any optimizations on objects that can change in ways that cannot be determined by the compiler.
Objects declared as volatile are omitted from optimization because their values can be changed by code outside the scope of current code at any time. See Understanding “volatile” qualifier in C for more details.
Can a variable be both const and volatile?
yes, the const means that the variable cannot be assigned a new value. The value can be changed by other code or pointer. For example the following program works fine.
int main(void)
{
const volatile int local = 10;
int *ptr = (int*) &local;
printf("Initial value of local : %d \n", local);
*ptr = 100;
printf("Modified value of local: %d \n", local);
return 0;
}
Write a program to print "hello world" without using a semicolon?
#include<stdio.h>
void main(){
if(printf("hello world")){} // It prints the ?hello world? on the screen.
}
Write a program to swap two numbers without using the third variable?
#include<stdio.h>
#include<conio.h>
main()
{
int a=10, b=20; //declaration of variables.
clrscr(); //It clears the screen.
printf("Before swap a=%d b=%d",a,b);
a=a+b;//a=30 (10+20)
b=a-b;//b=10 (30-20)
a=a-b;//a=20 (30-10)
printf("\nAfter swap a=%d b=%d",a,b);
getch();
}
Write a program to print Fibonacci series without using recursion?
#include<stdio.h>
#include<conio.h>
void main()
{
int n1=0,n2=1,n3,i,number;
clrscr();
printf("Enter the number of elements:");
scanf("%d",&number);
printf("\n%d %d",n1,n2);//printing 0 and 1
for(i=2;i<number;++i)//loop starts from 2 because 0 and 1 are already printed
{
n3=n1+n2;
printf(" %d",n3);
n1=n2;
n2=n3;
}
getch();
}
What are the different types of control structures in programming?
There are 3 main control structures in programming: Sequence, Selection and Repetition. Sequential control follows a top to bottom flow in executing a program, such that step 1 is first perform, followed by step 2, all the way until the last step is performed. Selection deals with conditional statements, which mean codes are executed depending on the evaluation of conditions as being TRUE or FALSE. This also means that not all codes may be executed, and there are alternative flows within. Repetitions are also known as loop structures, and will repeat one or two program statements set by a counter.
What is || operator and how does it function in a program?
The || is also known as the OR operator in C programming. When using || to evaluate logical conditions, any condition that evaluates to TRUE will render the entire condition statement as TRUE.
Can the “if” function be used in comparing strings?
No. “if” command can only be used to compare numerical values and single character values. For comparing string values, there is another function called strcmp that deals specifically with strings.
What are preprocessor directives?
Preprocessor directives are placed at the beginning of every C program. This is where library files are specified, which would depend on what functions are to be used in the program. Another use of preprocessor directives is the declaration of constants.Preprocessor directives begin with the # symbol.
What will be the outcome of the following conditional statement if the value of variable s is 10?
s >=10 && s < 25 && s!=12
The outcome will be TRUE. Since the value of s is 10, s >= 10 evaluates to TRUE because s is not greater than 10 but is still equal to 10. s< 25 is also TRUE since 10 is less then 25. Just the same, s!=12, which means s is not equal to 12, evaluates to TRUE. The && is the AND operator, and follows the rule that if all individual conditions are TRUE, the entire statement is TRUE.
Describe the order of precedence with regards to operators in C.
Order of precedence determines which operation must first take place in an operation statement or conditional statement. On the top most level of precedence are the unary operators !, +, – and &. It is followed by the regular mathematical operators (*, / and modulus % first, followed by + and -). Next in line are the relational operators <, <=, >= and >. This is then followed by the two equality operators == and !=. The logical operators && and || are next evaluated. On the last level is the assignment operator =.
What is wrong with this statement? myName = “Robin”;
You cannot use the = sign to assign values to a string variable. Instead, use the strcpy function. The correct statement would be: strcpy(myName, “Robin”);
How do you determine the length of a string value that was stored in a variable?
To get the length of a string value, use the function strlen(). For example, if you have a variable named FullName, you can get the length of the stored string value by using this statement: I = strlen(FullName); the variable I will now have the character length of the string value.
#define my_sizeof(type) (char *)(&type+1)-(char*)(&type)
How will you print numbers from 1 to 100 without using loop?
We can use recursion for this purpose.
/* Prints numbers from 1 to n */
void printNos(unsigned int n)
{
if(n > 0)
{
printNos(n-1);
printf("%d ", n);
}
}
What is volatile keyword?
The volatile keyword is intended to prevent the compiler from applying any optimizations on objects that can change in ways that cannot be determined by the compiler.
Objects declared as volatile are omitted from optimization because their values can be changed by code outside the scope of current code at any time. See Understanding “volatile” qualifier in C for more details.
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| KPIT Technologies Most Frequently Asked C Language Interview Questions Answers |
Can a variable be both const and volatile?
yes, the const means that the variable cannot be assigned a new value. The value can be changed by other code or pointer. For example the following program works fine.
int main(void)
{
const volatile int local = 10;
int *ptr = (int*) &local;
printf("Initial value of local : %d \n", local);
*ptr = 100;
printf("Modified value of local: %d \n", local);
return 0;
}
Write a program to print "hello world" without using a semicolon?
#include<stdio.h>
void main(){
if(printf("hello world")){} // It prints the ?hello world? on the screen.
}
Write a program to swap two numbers without using the third variable?
#include<stdio.h>
#include<conio.h>
main()
{
int a=10, b=20; //declaration of variables.
clrscr(); //It clears the screen.
printf("Before swap a=%d b=%d",a,b);
a=a+b;//a=30 (10+20)
b=a-b;//b=10 (30-20)
a=a-b;//a=20 (30-10)
printf("\nAfter swap a=%d b=%d",a,b);
getch();
}
Write a program to print Fibonacci series without using recursion?
#include<stdio.h>
#include<conio.h>
void main()
{
int n1=0,n2=1,n3,i,number;
clrscr();
printf("Enter the number of elements:");
scanf("%d",&number);
printf("\n%d %d",n1,n2);//printing 0 and 1
for(i=2;i<number;++i)//loop starts from 2 because 0 and 1 are already printed
{
n3=n1+n2;
printf(" %d",n3);
n1=n2;
n2=n3;
}
getch();
}
What are the different types of control structures in programming?
There are 3 main control structures in programming: Sequence, Selection and Repetition. Sequential control follows a top to bottom flow in executing a program, such that step 1 is first perform, followed by step 2, all the way until the last step is performed. Selection deals with conditional statements, which mean codes are executed depending on the evaluation of conditions as being TRUE or FALSE. This also means that not all codes may be executed, and there are alternative flows within. Repetitions are also known as loop structures, and will repeat one or two program statements set by a counter.
What is || operator and how does it function in a program?
The || is also known as the OR operator in C programming. When using || to evaluate logical conditions, any condition that evaluates to TRUE will render the entire condition statement as TRUE.
Can the “if” function be used in comparing strings?
No. “if” command can only be used to compare numerical values and single character values. For comparing string values, there is another function called strcmp that deals specifically with strings.
What are preprocessor directives?
Preprocessor directives are placed at the beginning of every C program. This is where library files are specified, which would depend on what functions are to be used in the program. Another use of preprocessor directives is the declaration of constants.Preprocessor directives begin with the # symbol.
What will be the outcome of the following conditional statement if the value of variable s is 10?
s >=10 && s < 25 && s!=12
The outcome will be TRUE. Since the value of s is 10, s >= 10 evaluates to TRUE because s is not greater than 10 but is still equal to 10. s< 25 is also TRUE since 10 is less then 25. Just the same, s!=12, which means s is not equal to 12, evaluates to TRUE. The && is the AND operator, and follows the rule that if all individual conditions are TRUE, the entire statement is TRUE.
Describe the order of precedence with regards to operators in C.
Order of precedence determines which operation must first take place in an operation statement or conditional statement. On the top most level of precedence are the unary operators !, +, – and &. It is followed by the regular mathematical operators (*, / and modulus % first, followed by + and -). Next in line are the relational operators <, <=, >= and >. This is then followed by the two equality operators == and !=. The logical operators && and || are next evaluated. On the last level is the assignment operator =.
What is wrong with this statement? myName = “Robin”;
You cannot use the = sign to assign values to a string variable. Instead, use the strcpy function. The correct statement would be: strcpy(myName, “Robin”);
How do you determine the length of a string value that was stored in a variable?
To get the length of a string value, use the function strlen(). For example, if you have a variable named FullName, you can get the length of the stored string value by using this statement: I = strlen(FullName); the variable I will now have the character length of the string value.