Using Macros Find Arithmetic Mean, Absolute Value, Biggest of 3 number and convert upper case alphabet to lower case: C Program

Problem Statement: Write down macro definitions for the following:

1. To find arithmetic mean of two numbers.
2. To find absolute value of a number.
3. To convert an upper case alphabet to lower case.
4. To obtain the biggest of three numbers.

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Video Tutorial: Using Macros Find Arithmetic Mean, Absolute Value, Biggest of 3 number and convert upper case alphabet to lower case: C Program

Source Code: Using Macros Find Arithmetic Mean, Absolute Value, Biggest of 3 number and convert upper case alphabet to lower case: C Program

#include<stdio.h>

#define MEAN(a, b)  ( (a + b) / 2.0 )
#define ABS(num)    ( (num > 0) ? num : (num * -1) )
#define LOWER(ch)   ( ch + 32 )
#define BIGGEST(a, b, c) ( (a > b && a > c) ? a : ( (b > c) ? b : c ) )

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

    do
    {
        printf("1. Find Arithmetic Mean of 2 numbers\n");
        printf("2. Find Absolute Value of a number\n");
        printf("3. Convert a Uppercase letter to lowercase\n");
        printf("4. Find Biggest of 3 numbers\n");

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

        switch(choice)
        {
            case 1: printf("Enter 2 numbers\n");
                    scanf("%f%f", &a, &b);
                    printf("Arithmetic Mean: %0.2f\n", MEAN(a, b));
                    break;
            case 2: printf("Enter a integer number\n");
                    scanf("%d", &num);
                    printf("Absolute value of |%d| is %d\n", num, ABS(num));
                    break;
            case 3: printf("Enter a uppercase alphabet\n");
                    fflush(stdin);
                    scanf("%c", &ch);

                    if( ch >= 65 && ch <= 90)
                        printf("To Lowercase: %c\n", LOWER(ch));
                    else
                        printf("Enter a valid uppercase alphabet\n");

                    break;
            case 4: printf("Enter 3 numbers\n");
                    scanf("%f%f%f", &a, &b,&c);
                    printf("Biggest no is %0.2f\n", BIGGEST(a, b, c));
                    break;
            default: printf("Please enter valid choice\n");
        }

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

        printf("\n");

    }while(repeat);

    return 0;
}

Output:
1. Find Arithmetic Mean of 2 numbers
2. Find Absolute Value of a number
3. Convert a Uppercase letter to lowercase
4. Find Biggest of 3 numbers

Enter your choice
1
Enter 2 numbers
41
14
Arithmetic Mean: 27.50

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

1. Find Arithmetic Mean of 2 numbers
2. Find Absolute Value of a number
3. Convert a Uppercase letter to lowercase
4. Find Biggest of 3 numbers

Enter your choice
2
Enter a integer number
5
Absolute value of |5| is 5

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

1. Find Arithmetic Mean of 2 numbers
2. Find Absolute Value of a number
3. Convert a Uppercase letter to lowercase
4. Find Biggest of 3 numbers

Enter your choice
2
Enter a integer number
-5
Absolute value of |-5| is 5

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

1. Find Arithmetic Mean of 2 numbers
2. Find Absolute Value of a number
3. Convert a Uppercase letter to lowercase
4. Find Biggest of 3 numbers

Enter your choice
3
Enter a uppercase alphabet
S
To Lowercase: s

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

1. Find Arithmetic Mean of 2 numbers
2. Find Absolute Value of a number
3. Convert a Uppercase letter to lowercase
4. Find Biggest of 3 numbers

Enter your choice
3
Enter a uppercase alphabet
$
Enter a valid uppercase alphabet

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

1. Find Arithmetic Mean of 2 numbers
2. Find Absolute Value of a number
3. Convert a Uppercase letter to lowercase
4. Find Biggest of 3 numbers

Enter your choice
4
Enter 3 numbers
20
40
50
Biggest no is 50.00

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

Formula and Logic

1. Arithmetic mean: If user enters two numbers, then we add those 2 numbers and divide it by 2 to get the result. If user inputs 3 numbers, we first add all these 3 numbers and divide it by 3 to get mean.

In this program, according to problem statement, we need to add 2 numbers and divide it by 2 to get the mean of those 2 user input numbers.

Since we’re taking 2 floating point numbers, we’re dividing the sum of two numbers by 2.0 and not by integer 2. If we divide float or double number with integer number 2, then there is possibility of getting wrong result.

Calculate Sum and Average of N Numbers without using Arrays: C Program

Average and Mean are same in mathematics.

2. Absolute Value: Absolute value is like distance. In whichever direction you move there can only be positive distance. You can’t walk negative 5 kilometre!

So for any integer input by the user, we return it’s positive value by multiplying it by -1, in case user input number is negative.

C Program To Find Absolute Value of a Number

Note: We could have used built-in method abs() from the library file stdlib.h to get absolute value of user input number. But to use a single built-in method abs() we must include all the things present in stdlib.h file, so we better write definition to calculate absolute value ourselves.

3. Convert a Uppercase alphabet to lowercase: We should know the ASCII value of A and Z, as well as ASCII value of a and z to get the result.

C Program To Print All ASCII Characters and Code

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.

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.

If you observe the ASCII values properly, you’ll know that there is a difference of 32 between a and A in it’s ASCII value. So, if user inputs a capital letter, then we simply add 32 to it and display the character – which will be its corresponding lowercase alphabet.

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);

4. Biggest of 3 Numbers: Here we make use of nested ternary or conditional operator. If a is greater than b and c, then we return value of a. ORELSE if b is greater than c, then we return the value of b, else we return the value of c.

Biggest of 3 Numbers Using Ternary Operator: C

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 BIGGEST(a, b, c).

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