C Aptitude Questions and answers with explanation

C Aptitude 24
C program is one of most popular programming language which is used for core level of coding across the board. C program is used for operating systems, embedded systems, system engineering, word processors,hard ware drivers, etc.

In this site, we have discussed various type of C programs till date and from now on, we will move further by looking at the C aptitude questions.

In the coming days, we will post C aptitude questions, answers and explanation for interview preparations.

The C aptitude questions and answers for those questions along with explanation for the interview related queries.

We hope that this questions and answers series on C program will help students and freshers who are looking for a job, and also programmers who are looking to update their aptitude on C program.
Some of the illustrated examples will be from the various companies, and IT industry experts.
Read more about C Programming Language . and read the C Programming Language (2nd Edition). by K and R.

Predict the output or error(s) for the following:

C aptitude 24.1

  main()
{
printf("%x",-1<<4);
}


Answer: fff0

Explanation: -1 is internally represented as all 1’s. When left shifted four times the least significant 4 bits are filled with 0’s.The %x format specifier specifies that the integer value be printed as a hexadecimal value.

C aptitude 24.2

   main()
{
char string[]="Hello World";
display(string);
}
void display(char *string)
{
printf("%s",string);
}

Answer: Compiler Error : Type mismatch in redeclaration of function display

Explanation:In third line, when the function display is encountered, the compiler doesn’t know anything about the function display. It assumes the arguments and return types to be integers, (which is the default type). When it sees the actual function display, the arguments and type contradicts with what it has assumed previously. Hence a compile time error occurs.

C aptitude 24.3

      main()
{
int c=- -2;
printf("c=%d",c);
}

Answer:c=2

Explanation: Here unary minus (or negation) operator is used twice. Same maths rules applies, ie. minus * minus= plus.
Note: However you cannot give like –2. Because — operator can only be applied to variables as a decrement operator (eg., i–). 2 is a constant and not a variable.

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C program to hide the mouse pointers.

C program to hide the mouse pointers.
In this program, we hide the mouse pointers using graphics.h and dos.h library functions.
To use graphics.h, we have to install the drivers in to the the system by using the initgraph() function.
In this program,we also check the condition that mouse pointer is available or not. Read more about C Programming Language . and read the C Programming Language (2nd Edition). by K and R.

/***********************************************************
* You can use all the programs on www.c-program-example.com
* for personal and learning purposes. For permissions to use the
* programs for commercial purposes,
* contact info@c-program-example.com
* To find more C programs, do visit www.c-program-example.com
* and browse!
*
* Happy Coding
***********************************************************/

#include<graphics.h>
#include<conio.h>
#include<dos.h>

void showmouseptr();
void hidemouseptr();

union REGS i, o;

int main()
{
int count = 1, gd = DETECT, gm;

initgraph(&gd,&gm,"C:\TC\BGI");/*check your path, to install the drivers in to the the system*/

i.x.ax = 0;
int86(0X33,&i,&o);
if(o.x.ax == 0)
{
printf("nt Sorry! Mouse support not available !");
}
else
{
showmouseptr();

while(count<=10)
{
getch();
count++;
if(count%2==0)
hidemouseptr();
else
showmouseptr();
}
}

getch();
return 0;
}


void showmouseptr()
{
i.x.ax = 1;
int86(0X33,&i,&o);
}

void hidemouseptr()
{
i.x.ax = 2; // to hide mouse
int86(0X33,&i,&o);
}
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K & R C Exercise Solutions.

We have already provided solutions to all the exercises in the bookC Programming Language (2nd Edition) popularly known as K & R C book.

In this blog post I will give links to all the chapters of the “C Programming Language (2nd Edition)” popularly known as K & R C book for easy reference.

  1. Chapter 1: A Tutorial Introduction
  2. Chapter 2: Types, Operators and Expressions
  3. Chapter 3: Control Flow
  4. Chapter 4: Functions and Program Structure
  5. Chapter 5: Pointers and Arrays
  6. Chapter 6: Structures
  7. Chapter 7: Input and Output
You can purchase the book from here or here.

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C Aptitude Questions and answers with explanation

C Aptitude 24
C program is one of most popular programming language which is used for core level of coding across the board. C program is used for operating systems, embedded systems, system engineering, word processors,hard ware drivers, etc.

In this site, we have discussed various type of C programs till date and from now on, we will move further by looking at the C aptitude questions.

The C aptitude questions and answers for those questions along with explanation for the interview related queries.

We hope that this questions and answers series on C program will help students and freshers who are looking for a job, and also programmers who are looking to update their aptitude on C program.
Some of the illustrated examples will be from the various companies, and IT industry experts.
Read more about how to prepare and write the C Aptitude Exams?
Read more about C Programming Language . and read the C Programming Language (2nd Edition). by K and R.

 

Predict the output or error(s) for the following:

C aptitude 24.1

main()

{

char str[4]="test";

printf("%s",str);


}

Answer: test#$634278621@!

Explanation: The character array has the memory just enough to hold the string “test” and doesn’t have enough space to store the terminating null character. So it prints the test correctly and continues to print garbage values till it accidentally comes across a NULL character.

C aptitude 24.2

 
main()

{

char * str = "hello";

char * ptr = str;

char least = 127;

while (*ptr++)

least = (*ptr <least ) ?*ptr :least;

printf("%d",least);

}

Answer: 0

Explanation: After ‘ptr’ reaches the end of the string the value pointed by ‘str’ is ‘’. So the value of ‘str’ is less than that of ‘least’. So the value of ‘least’ finally is 0.

C aptitude 24.3

     main()

{

int i = 257;

int *iPtr = &i;

printf("%d %d", *((char*)iPtr), *((char*)iPtr+1) );

}

Answer: 11

Explanation: The integer value 257 is stored in the memory as, 00000001 00000001, so the individual bytes are taken by casting it to char * and get printed.

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C Program to change the text colors.

Write a C Program to change the text colors.
In this program, we give the example of changing the text colors, background colors using conio.h library.
Syntax: void textcolor(int_color);
Here color is the integer variable, you can specify a color name also, but it should be a proper color name in capital letters.
Read more about C Programming Language . and read the C Programming Language (2nd Edition). by K and R.

/***********************************************************
* You can use all the programs on www.c-program-example.com
* for personal and learning purposes. For permissions to use the
* programs for commercial purposes,
* contact info@c-program-example.com
* To find more C programs, do visit www.c-program-example.com
* and browse!
*
* Happy Coding
***********************************************************/

#include<stdio.h>
#include<conio.h>
int main()
{
clrscr();
textcolor(BLUE); // Change font colour to blue
textbackground(WHITE); //change the background colour to white
cprintf("Color is Blue with white backgroundnn");
clrscr();
textcolor(RED+BLINK);//this one is blinking the text
cprintf("Color is RED with blinkingnn");
return 0;
}
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C Aptitude Questions and answers with explanation

C Aptitude 23
C program is one of most popular programming language which is used for core level of coding across the board. C program is used for operating systems, embedded systems, system engineering, word processors,hard ware drivers, etc.

In this site, we have discussed various type of C programs till date and from now on, we will move further by looking at the C aptitude questions.

The C aptitude questions and answers for those questions along with explanation for the interview related queries.

We hope that this questions and answers series on C program will help students and freshers who are looking for a job, and also programmers who are looking to update their aptitude on C program.
Some of the illustrated examples will be from the various companies, and IT industry experts.
Read more about how to prepare and write the C Aptitude Exams?
Read more about C Programming Language . and read the C Programming Language (2nd Edition). by K and R.

 

Predict the output or error(s) for the following:

C aptitude 23.1

void main(){
int res;
res= 56>76 ? return 0:return 1;
printf("%d",res);
}

Answer: Compilation error.

Explanation: We cannot use return keyword in conditional operator.

C aptitude 23.2
Note: here input for command line argument is, example 5 4 7 8

 
/* example.c */
#include

int main(int argc, char *argv[])
{
int j;
j = argv[1] + argv[2] + argv[3] + argv[4];
printf("%d", j);
return 0;
}

Answer: Error

Explanation: Command line arguments are string types, we can’t add or do the arithmetic operations on string types in C, we have to convert the argv[] to the integer types using atoi function.

C aptitude 23.3

     int main()
{
int num1 = 123;
float num2 = 123.0;
if(num1 == num2)
printf("num1 and num2 are equal");
else
printf("num1 and num2 are not equal");
return 0;
}

Answer: num1 and num2 are equal

Explanation: This is the tricky question, in if statement we are comparing 123=123.0, condition satisfied, so the result is num1 and num2 are equal.

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C program to sort a string

C Strings:
Write a C program to sort a string.
In this program we sort the string using bubble sort technique.
Bubble Sort is the simplest and easiest sorting technique. In this technique, the two successive items A[i] and A[i+1] are exchanged whenever A[i]>=A[i+1]. The larger values sink to the bottom of the array and hence it is called sinking sort. The end of each pass smaller values gradually “bubble” their way upward to the top(like air bubbles moving to surface of water) and hence called bubble sort.
Read more about C Programming Language . and read the C Programming Language (2nd Edition). by K and R.

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* You can use all the programs on  www.c-program-example.com
* for personal and learning purposes. For permissions to use the
* programs for commercial purposes,
* contact info@c-program-example.com
* To find more C programs, do visit www.c-program-example.com
* and browse!
* 
*                      Happy Coding
***********************************************************/

#include<stdio.h>
#include<string.h>
int main(){
    int i,j,n;
    char str[50],temp[50];
    printf("Enter a String:nn");
    scanf("%s",str);
    n=strlen(str);
    for(i=0;i<=n;i++)
    for(j=i+1;j<=n;j++){
        if(strcmp(str[i],str[j])>0){
            strcpy(temp,str[i]);
            strcpy(str[i],str[j]);
            strcpy(str[j],temp);
        }
    }
    printf("The sorted string is:%sn",str);
    return 0;
}
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C Aptitude Questions and answers with explanation

C Aptitude 22
C program is one of most popular programming language which is used for core level of coding across the board. C program is used for operating systems, embedded systems, system engineering, word processors,hard ware drivers, etc.

In this site, we have discussed various type of C programs till date and from now on, we will move further by looking at the C aptitude questions.

In the coming days, we will post C aptitude questions, answers and explanation for interview preparations.

The C aptitude questions and answers for those questions along with explanation for the interview related queries.

We hope that this questions and answers series on C program will help students and freshers who are looking for a job, and also programmers who are looking to update their aptitude on C program.
Some of the illustrated examples will be from the various companies, and IT industry experts.
Read more about how to prepare and write the C Aptitude Exams?
Read more about C Programming Language . and read the C Programming Language (2nd Edition). by K and R.

 

Predict the output or error(s) for the following:

C aptitude 22.1

int main()
{
int *ptr;
*ptr=100;
return 0;
}

Answer: No error.

Explanation: At the time of compilation ,their is a no error, but at the run time you may caught up with the error “null pointer assignment”, because variable *ptr is not initialized during the declaration..

C aptitude 22.2

 
int main()
{
int example[]={2, 3, 4, 1, 6};
printf("%u, %u, %un", example, &example[0], &example);
return 0;
}

Answer: 1200 1200 1200

Explanation: In the printf statement example, &example are returning the base address of the array, i.e 1200, and &example[0] pointing to the address of the first element of array example, i.e 1200, so answer is 1200 1200 1200.

C aptitude 22.3

     int main()
{
char str1[20] = "Hello", str2[20] = " World";
printf("%sn", strcpy(str2, strcat(str1, str2)));
return 0;
}

Answer: Hello World

Explanation: In the printf statement strcat function concatenates or appends the string str2 to string str1, so str1 contains Hello World, then strcpy function copies the value of string str1 to string str2, so output is Hello World.

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C Aptitude Questions and answers with explanation

C Aptitude 20
C program is one of most popular programming language which is used for core level of coding across the board. C program is used for operating systems, embedded systems, system engineering, word processors,hard ware drivers, etc.

In this site, we have discussed various type of C programs till date and from now on, we will move further by looking at the C aptitude questions.

In the coming days, we will post C aptitude questions, answers and explanation for interview preparations.

The C aptitude questions and answers for those questions along with explanation for the interview related queries.

We hope that this questions and answers series on C program will help students and freshers who are looking for a job, and also programmers who are looking to update their aptitude on C program.
Some of the illustrated examples will be from the various companies, and IT industry experts.
Read more about C Programming Language . and read the C Programming Language (2nd Edition). by K and R.

Predict the output or error(s) for the following:

C aptitude 20.1

  main()
{
int *j;
{
int i=10;
j=&i;
}
printf("%d",*j);
}


Answer: 10

Explanation: The variable i is a block level variable and the visibility is inside that block only. But the lifetime of i is lifetime of the function so it lives up to the exit of main function. Since the i is still allocated space, *j prints the value stored in i since j points i.

C aptitude 20.2

   main()
{
int i=-1;
-i;
printf("i = %d, -i = %d n",i,-i);
}


Answer: i = -1, -i = 1

Explanation: -i is executed and this execution doesn’t affect the value of i. In printf first you just print the value of i. After that the value of the expression -i = -(-1) is printed.

C aptitude 20.3

     main()
{
const int i=4;
float j;
j = ++i;
printf("%d %f", i,++j);
}

Answer: Compiler error

Explanation: i is a constant. you cannot change the value of constant

C aptitude 20.4

      main()
{
int a[2][2][2] = { {10,2,3,4}, {5,6,7,8} };
int *p,*q;
p=&a[2][2][2];
*q=***a;
printf("%d..%d",*p,*q);
}

Answer: garbagevalue..1

Explanation: p=&a[2][2][2] you declare only two 2D arrays. but you are trying to access the third 2D(which you are not declared) it will print garbage values. *q=***a starting address of a is assigned integer.

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Write a C program to reverse a string using pointers.

C Strings:
Write a C program to reverse a string using pointers.
In this program, we reverse the given string by using the pointers. Here we use the two pointers to reverse the string, strptr holds the address of given string and in loop revptr holds the address of the reversed string.
Read more about C Programming Language . and read the C Programming Language (2nd Edition). by K and R.

/***********************************************************
* You can use all the programs on www.c-program-example.com
* for personal and learning purposes. For permissions to use the
* programs for commercial purposes,
* contact info@c-program-example.com
* To find more C programs, do visit www.c-program-example.com
* and browse!
*
* Happy Coding
***********************************************************/

#include<stdio.h>
int main(){
int i=-1;
char str[100];
char rev[100];
char *strptr = str;
char *revptr = rev;
printf("Enter the string:n");
scanf("%s",str);
while(*strptr)
{
strptr++;
i++;
}
while(i >=0) {
strptr--;
*strptr = *revptr;
revptr++;
--i;
}
printf("nn Reversed string is:%s",rev);
return 0;
}



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