C programming - Part 9

Using Macros Find Area and Perimeter of Triangle, Square, Circle: C Program

Problem State: Write macro definitions with arguments for calculation of area and perimeter of a triangle, a square and a circle.

Store these macro definitions in a file called “areaperi.h”. Include this file in your program, and call the macro definitions for calculating area and perimeter for different squares, triangles and circles.

Problem Statement Analysis

1. We need to write macro definitions which accept arguments.
2. We need to write macro definitions to calculate area and perimeter of triangle, square and circle.
3. We need to write macro definition inside a separate file called areaperi.h and then include this header file into our source file and make use of the macro definitions to calculate area and perimeter of Triangle, Square and Circle for various user inputs.

Video Tutorial: Using Macros Find Area and Perimeter of Triangle, Square, Circle: C Program

YouTube Link: https://www.youtube.com/watch?v=lR50ONlpDNw [Watch the Video In Full Screen.]

Source Code: Using Macros Find Area and Perimeter of Triangle, Square, Circle: C Program

areaperi.h

#include

#define TRI_PERI(a, b, c) (a + b + c)
#define SP(a, b, c) ( (a + b + c) / 2.0 )
#define TRI_AREA(a, b, c) ( sqrt( SP(a,b,c) * \
                                 ( SP(a,b,c) - a ) *\
                                  (SP(a,b,c) - b) * \
                                  (SP(a,b,c) - c)) )

#define SQR_PERI(s) (4 * s)
#define SQR_AREA(s) (s * s)

#define C_PERI(r) (2 * M_PI * r)
#define C_AREA(r) (M_PI * r * r)

main.c

#include
#include "areaperi.h"

int main()
{
    float a, b, c, side, radius;
    int choice, repeat;

    do
    {
        printf("1. Area of Triangle\n");
        printf("2. Perimeter of Triangle\n");
        printf("3. Area of Square\n");
        printf("4. Perimeter of Square\n");
        printf("5. Area of Circle\n");
        printf("6. Perimeter of Circle\n");

        printf("\nEnter your choice\n");
        scanf("%d", &choice);

        switch(choice)
        {
            case 1: printf("Enter 3 sides of a Triangle\n");
                    scanf("%f%f%f", &a, &b, &c);
                    printf("Area of Trianlge is %0.2f\n", TRI_AREA(a,b,c));
                    break;
            case 2: printf("Enter 3 sides of a Triangle\n");
                    scanf("%f%f%f", &a, &b, &c);
                    printf("Perimeter of Trianlge is %0.2f\n", TRI_PERI(a,b,c));
                    break;
            case 3: printf("Enter length of side of Square\n");
                    scanf("%f", &side);
                    printf("Area of Square is %0.2f", SQR_AREA(side));
                    break;
            case 4: printf("Enter length of side of Square\n");
                    scanf("%f", &side);
                    printf("Perimeter of Square is %0.2f", SQR_PERI(side));
                    break;
            case 5: printf("Enter Radius of Circle\n");
                    scanf("%f", &radius);
                    printf("Area of Circle is %0.2f\n", C_AREA(radius));
                    break;
            case 6: printf("Enter Radius of Circle\n");
                    scanf("%f", &radius);
                    printf("Circumference of Circle is %0.2f\n", C_PERI(radius));
                    break;
            default: printf("\nPlease enter valid choice\n");
        }

        printf("\n\nDo you want to continue? Ans: 0 or 1\n");
        scanf("%d", &repeat);

        printf("\n");

    }while(repeat);

    return 0;
}

Output:
1. Area of Triangle
2. Perimeter of Triangle
3. Area of Square
4. Perimeter of Square
5. Area of Circle
6. Perimeter of Circle

Enter your choice
1
Enter 3 sides of a Triangle
5
6
9
Area of Trianlge is 14.14

Do you want to continue? Ans: 0 or 1
1

1. Area of Triangle
2. Perimeter of Triangle
3. Area of Square
4. Perimeter of Square
5. Area of Circle
6. Perimeter of Circle

Enter your choice
2
Enter 3 sides of a Triangle
5
6
9
Perimeter of Trianlge is 20.00

Do you want to continue? Ans: 0 or 1
1

1. Area of Triangle
2. Perimeter of Triangle
3. Area of Square
4. Perimeter of Square
5. Area of Circle
6. Perimeter of Circle

Enter your choice
3
Enter length of side of Square
5
Area of Square is 25.00

Do you want to continue? Ans: 0 or 1
1

1. Area of Triangle
2. Perimeter of Triangle
3. Area of Square
4. Perimeter of Square
5. Area of Circle
6. Perimeter of Circle

Enter your choice
4
Enter length of side of Square
5
Perimeter of Square is 20.00

Do you want to continue? Ans: 0 or 1
1

1. Area of Triangle
2. Perimeter of Triangle
3. Area of Square
4. Perimeter of Square
5. Area of Circle
6. Perimeter of Circle

Enter your choice
5
Enter Radius of Circle
5.5
Area of Circle is 95.03

Do you want to continue? Ans: 0 or 1
1

1. Area of Triangle
2. Perimeter of Triangle
3. Area of Square
4. Perimeter of Square
5. Area of Circle
6. Perimeter of Circle

Enter your choice
6
Enter Radius of Circle
5.5
Circumference of Circle is 34.56

Do you want to continue? Ans: 0 or 1
0

Formulas To Calculate Area and Perimeter

We’ve written the formula to calculate area and perimeter inside areaperi.h file, as macro expansion. Below we list all the formulas we’re using in our program:

Perimeter of a Triangle: ( a + b + c)
where: a, b, and c are lengths of sides of the triangle.

Semi-perimeter of a Triangle: ( (a + b + c) / 2 )
where: a, b, and c are lengths of sides of the triangle.

Area of a Triangle: sqrt( S x (S – a) x (S – b) x (S – c) )
where: a, b, and c are lengths of sides of the triangle.
S is the semi-perimeter.

Perimeter of Square: ( 4 x side )
where: side is the length of side of the square.

Area of Square: ( side x side)
where: side is the length of side of the square.

Perimeter or Circumference of Circle: ( 2 x PI x r )
Area of a Circle: ( PI x r x r )
where: r is radius of the circle.
PI is approximately equal to 3.14

Note: M_PI is a macro present inside math.h library file and has value of PI.

Logic

We’ve included areaperi.h into main.c file. Now we can make use of all the macros we’ve defined inside areaperi.h

Users are provided with options to select the preferred operations like:
1. Area of Triangle
2. Perimeter of Triangle
3. Area of Square
4. Perimeter of Square
5. Area of Circle
6. Perimeter of Circle

Based on user selection appropriate block of code inside switch-case is executed, wherein we place the relevant macro template to get the desired result.

Note: We can continue writing macro expansion in next line by making use of macro continuation operator(\). You can see that we’ve broken the line and written the code in next line inside macro expansion of TRI_AREA.

For list of all c programming interviews / viva question and answers visit: C Programming Interview / Viva Q&A List

For full C programming language free video tutorial list visit:C Programming: Beginner To Advance To Expert

Using Macros Check For Uppercase / Lowercase and Alphabet or Not and Biggest of 2 Numbers: C Program

Problem State: Write down macro definitions for the following:
1. To test whether a character is a small case letter or not.
2. To test whether a character is an upper case letter or not.
3. To test whether a character is an alphabet or not. Make use of the macros you defined in 1 and 2 above.
4. To obtain the bigger of two numbers.

Problem Statement Analysis

1. We need to write 4 Macro definitions.
2. We must write macros to find upper and lower case, and then make use of these two macros to find if user entered character is alphabet or not.
3. We can find biggest of 2 numbers by using Ternary / conditional operator in macro expansion.

Video Tutorial: Using Macros Check For Uppercase / Lowercase and Alphabet or Not and Biggest of 2 Numbers: C Program

YouTube Link: https://www.youtube.com/watch?v=EEGLYe2buxk [Watch the Video In Full Screen.]

Source Code: Using Macros Check For Uppercase / Lowercase and Alphabet or Not and Biggest of 2 Numbers: C Program

#include

#define isUPPER(ch) ( ch >= 'A' && ch <= 'Z' )
#define isLOWER(ch) ( ch >= 'a' && ch <= 'z' )
#define isALPHABET(ch) ( isUPPER(ch) || isLOWER(ch) )
#define BIGGEST(a, b) ( ( a > b ) ? \
                       printf("%d is the biggest\n", a) : \
                       printf("%d is the biggest\n", b) )

int main()
{
    int a, b, repeat;
    char ch, choice;

    do
    {
        printf("1. Check if entered character is upper or lower case\n");
        printf("2. Check if entered character is alphabet or not\n");
        printf("3. Find biggest of 2 numbers\n");

        printf("\nEnter your choice\n");
        scanf(" %c", &choice);

        switch(choice)
        {
            case '1': printf("\nEnter a character\n");
                      scanf(" %c", &ch);

                      if( isUPPER(ch) )
                      {
                          printf("Entered character is upper case letter\n");
                      }
                      else if( isLOWER(ch) )
                      {
                          printf("Entered character is lower case letter\n");
                      }
                      else
                      {
                          printf("Please enter a valid alphabet\n");
                      }

                      break;
            case '2': printf("\nEnter a character\n");
                      scanf(" %c", &ch);

                      if( isALPHABET(ch) )
                      {
                          printf("Entered character is an alphabet\n");
                      }
                      else
                      {
                          printf("Entered character is not an alphabet\n");
                      }
                      break;
            case '3': printf("\nEnter 2 numbers\n");
                      scanf("%d%d", &a, &b);

                      BIGGEST(a, b);

                      break;
            default:  printf("\nPlease enter valid choice\n");
        }

        printf("\n\nDo you want to continue? Ans: 0 or 1\n");
        scanf("%d", &repeat);

        printf("\n");
        fflush(stdin);

    }while(repeat);

    return 0;
}

Output:
1. Check if entered character is upper or lower case
2. Check if entered character is alphabet or not
3. Find biggest of 2 numbers

Enter your choice
1

Enter a character
S
Entered character is upper case letter

Do you want to continue? Ans: 0 or 1
1

1. Check if entered character is upper or lower case
2. Check if entered character is alphabet or not
3. Find biggest of 2 numbers

Enter your choice
1

Enter a character
s
Entered character is lower case letter

Do you want to continue? Ans: 0 or 1
1

1. Check if entered character is upper or lower case
2. Check if entered character is alphabet or not
3. Find biggest of 2 numbers

Enter your choice
1

Enter a character
$
Please enter a valid alphabet

Do you want to continue? Ans: 0 or 1
1

1. Check if entered character is upper or lower case
2. Check if entered character is alphabet or not
3. Find biggest of 2 numbers

Enter your choice
2

Enter a character
A
Entered character is an alphabet

Do you want to continue? Ans: 0 or 1
1

1. Check if entered character is upper or lower case
2. Check if entered character is alphabet or not
3. Find biggest of 2 numbers

Enter your choice
2

Enter a character
&
Entered character is not an alphabet

Do you want to continue? Ans: 0 or 1
1

1. Check if entered character is upper or lower case
2. Check if entered character is alphabet or not
3. Find biggest of 2 numbers

Enter your choice
3

Enter 2 numbers
14
50
50 is the biggest

Do you want to continue? Ans: 0 or 1
0

Here we are using do-while loop to repeatedly show the user choices: If user enters 1, the choices are shown once again. If the user enters 0, then control exits the do-while loop.

Choice 1: Upper or Lower Case Alphabet

All the characters have ASCII value associated with it in C programming. So internally it checks the ASCII value of user entered character against the ASCII values of “A” to “Z”.

ASCII value range of upper case alphabets:
ASCII value of A is 65.
ASCII value of B is 66.
ASCII value of C is 67.

and so on till Z ..

ASCII value of Z is 90.

So all the ASCII values between 65 and 90 (including 65 and 90) are Capital letter alphabets.

Similarly, below we’ve listed the ASCII values of lower case alphabets.

ASCII value range of lower case alphabets:
ASCII value of a is 97.
ASCII value of b is 98.
ASCII value of c is 99.

and so on till z ..

ASCII value of z is 122.

So all the ASCII values between 97 and 122 (including 97 and 122) are Lower case letter alphabets.

Choice 2: Alphabet or Not

According to our problem statement we need to use the macros we defined for “Choice 1” to evaluate if the user entered character is alphabet or not. So if the user entered character is upper or lower case latter than its alphabet or else its not an alphabet.

Choice 3: Biggest of Two Numbers

Inside macro expansion we make use of ternary / conditional operator to find biggest of 2 numbers.

Bug in accepting character as input

When you input some data via console window and hit enter key, the enter key or the new line character gets stored inside input buffer. If you’re accepting a single character from keyboard via scanf() function, often times it gets confused with the input buffer and thinks that the user has pressed the enter key as the input character. We can avoid it in 3 ways:

1. Use double scanf() function, as illustrated in above video tutorial.
2. Use a space before %c inside scanf() method.
3. Use fflush(stdin) before every scanf() method which accepts a single character value.

Note: Since we might start to input information from the keyboard repeatedly inside do-while block, scanf() method keeps checking the input buffer. And often times it gets confused with the input buffer and thinks that the user has pressed the enter key. To avoid that we flush out the previous buffer present in input device(ex: keyboard) using function fflush(). fflush takes stdin as argument, so that it can clear the buffer of standard input device. fflush(stdin);

#include

#define isUPPER(ch) ( ch >= 'A' && ch <= 'Z' )
#define isLOWER(ch) ( ch >= 'a' && ch <= 'z' )
#define isALPHABET(ch) ( isUPPER(ch) || isLOWER(ch) )
#define BIGGEST(a, b) ( ( a > b ) ? \
                       printf("%d is the biggest\n", a) : \
                       printf("%d is the biggest\n", b) )

int main()
{
    int a, b, repeat;
    char ch, choice;

    do
    {
        printf("1. Check if entered character is upper or lower case\n");
        printf("2. Check if entered character is alphabet or not\n");
        printf("3. Find biggest of 2 numbers\n");

        printf("\nEnter your choice\n");
        scanf("%c", &choice);

        switch(choice)
        {
            case '1': printf("\nEnter a character\n");
                      fflush(stdin);
                      scanf("%c", &ch);

                      if( isUPPER(ch) )
                      {
                          printf("Entered character is upper case letter\n");
                      }
                      else if( isLOWER(ch) )
                      {
                          printf("Entered character is lower case letter\n");
                      }
                      else
                      {
                          printf("Please enter a valid alphabet\n");
                      }

                      break;
            case '2': printf("\nEnter a character\n");
                      fflush(stdin);
                      scanf("%c", &ch);

                      if( isALPHABET(ch) )
                      {
                          printf("Entered character is an alphabet\n");
                      }
                      else
                      {
                          printf("Entered character is not an alphabet\n");
                      }
                      break;
            case '3': printf("\nEnter 2 numbers\n");
                      scanf("%d%d", &a, &b);

                      BIGGEST(a, b);

                      break;
            default:  printf("\nPlease enter valid choice\n");
        }

        printf("\n\nDo you want to continue? Ans: 0 or 1\n");
        scanf("%d", &repeat);

        printf("\n");
        fflush(stdin);

    }while(repeat);

    return 0;
}

In above source code we’re making use of fflush(stdin) before every scanf() method which accepts single character. fflush(stdin) flushes out the previous buffer present in input device(ex: Keyboard).

For list of all c programming interviews / viva question and answers visit: C Programming Interview / Viva Q&A List

For full C programming language free video tutorial list visit:C Programming: Beginner To Advance To Expert

C Program To Print Multiplication Table Using Macros

In this video lets see how we can print multiplication table(from 1 to 10) for any positive user input value, using Macros.

Video Tutorial: C Program To Print Multiplication Table Using Macros

YouTube Link: https://www.youtube.com/watch?v=1IaEnPHRalw [Watch the Video In Full Screen.]

Source Code: C Program To Print Multiplication Table Using Macros

#include

#define MULTI(num, count) printf("%d x %d = %d\n", num, count, (num*count))

int main()
{
    int num, count = 1;

    printf("Enter a positive number\n");
    scanf("%d", &num);

    printf("\nMultiplication Table for %d is: \n\n", num);

    while(count <= 10)
    {
        MULTI(num, count);
        count++;
    }

    return 0;
}

Output 1:
Enter a positive number
5

Multiplication Table for 5 is:

5 x 1 = 5
5 x 2 = 10
5 x 3 = 15
5 x 4 = 20
5 x 5 = 25
5 x 6 = 30
5 x 7 = 35
5 x 8 = 40
5 x 9 = 45
5 x 10 = 50

Output 2:
Enter a positive number
4

Multiplication Table for 4 is:

4 x 1 = 4
4 x 2 = 8
4 x 3 = 12
4 x 4 = 16
4 x 5 = 20
4 x 6 = 24
4 x 7 = 28
4 x 8 = 32
4 x 9 = 36
4 x 10 = 40

Here we are initializing variable count to 1 and iterating the while loop until count is less than or equal to 10. For each iteration we’re executing macro MULTI(num, count). But before compilation itself preprocessor will have replaced MULTI(num, count) by its macro expansion, which is printf(“%d x %d = %d\n”, num, count, (num*count)).

Note: If you see \ inside macro expansion – it is called as Macro continuation(\) operator. It is used to continue the code in next line, in macro expansion.

For list of all c programming interviews / viva question and answers visit: C Programming Interview / Viva Q&A List

For full C programming language free video tutorial list visit:C Programming: Beginner To Advance To Expert

Positive or Negative or Zero Using Macros: C Program

C Program to check whether the user input integer number is positive, negative or zero using Macros and ternary / Conditional operator.

Logic

If user input number is greater than 0, then the number is positive. If user input number is less than 0, then the number is negative. If neither of the above 2 conditions are true, then the number is zero.

Video Tutorial: Positive or Negative or Zero Using Macros: C Program

YouTube Link: https://www.youtube.com/watch?v=RNSLLP0buyk [Watch the Video In Full Screen.]

Source Code: Positive or Negative or Zero Using Macros: C Program

#include

#define SIGN(num) ( (num > 0) ? \
                   printf("POSITIVE") : \
                   (num < 0) ? printf("NEGATIVE") : \
                   printf("ZERO"))

int main()
{
    int num;

    printf("Enter a number\n");
    scanf("%d", &num);

    SIGN(num);

    return 0;
}

Output 1:
Enter a number
5
POSITIVE

Output 2:
Enter a number
-2
NEGATIVE

Output 3:
Enter a number
0
ZERO

Here the macro template SIGN(num) will be replaced by its corresponding macro expansion ( (num > 0) printf(“POSITIVE”) : (num < 0) ? printf(“NEGATIVE”) : printf(“ZERO”)) by preprocessor. And if user input number is greater than 0, it’ll print POSITIVE else it’ll print NEGATIVE. If neither of those 2 conditions are true, then it’ll print ZERO.

In our program we’re using Macro Continuation (\) Preprocessor Operator: C Program in macro expansion to break from the line and continue the logic in new/next line.

For list of all c programming interviews / viva question and answers visit: C Programming Interview / Viva Q&A List

For full C programming language free video tutorial list visit:C Programming: Beginner To Advance To Expert

Even or Odd Number using Macros: C Program

Lets write a C program to find if the user input number is odd or even, using Macros.

Logic To Find Even Or ODD

If user input number is perfectly divisible by 2, then it’s Even number orelse it’s Odd number.

Video Tutorial: Even or Odd Number using Macros: C Program

YouTube Link: https://www.youtube.com/watch?v=QtiHjwNZ7zg [Watch the Video In Full Screen.]

Source Code: Even or Odd Number using Macros: C Program

#include
#define ODD_EVEN(num) ( (num % 2 == 0) ? printf("Even\n") : printf("ODD\n") )

int main()
{
    int num;

    printf("Enter a positive number\n");
    scanf("%d", &num);

    ODD_EVEN(num);

    return 0;
}

Output 1:
Enter a positive number
5
ODD

Output 2:
Enter a positive number
6
Even

In above program the macro template ODD_EVEN(num) will be replaced by it’s macro expansion ( (num % 2 == 0) ? printf(“Even\n”) : printf(“ODD\n”) ) and hence if the user input number is perfectly divisible by 2, then EVEN will be printed else ODD will be printed.

For list of all c programming interviews / viva question and answers visit: C Programming Interview / Viva Q&A List

For full C programming language free video tutorial list visit:C Programming: Beginner To Advance To Expert