Sequential Programs in C

This is a list of some simple programs written in C after “Hello World”. It consists of programs like reversing a number, swapping variables, adding the sum of digits of a number, displaying the ASCII code of a character, Temperature Conversion etc. These can serve as first steps for a student new to C/programming. Any kind of doubt / query is most welcomed.

1. Write a C program to find the sum of individual digits of a positive 3 digit integer.

//Program to find the sum of digits of a 3-digit number
#include
main()
{	int num, sum;
	printf("Enter a 3-digit number : ");
	scanf("%d" , &num);
	sum = num/100;
        num%=100;
	sum+=num/10;
	num%=10;
	sum+=num;
	printf("Sum of digits = %d\n" , sum);
}

2. Write a C program to covert Fahrenheit to Celsius.

//Program to convert Temperature from Fahrenheit to Celsius Scale
#include
main()
{	float fah, cel;
	printf ("Enter temperature in Fahrenheit scale : ");
	scanf ("%f", &fah);
	cel = 5*(fah-32)/9;
	printf("%f Fahrenheit = %f Celsius\n", fah, cel);
}

3. WAP to swap the values of 3 variables without using 4th variable

//Program to swap the value of 3 integer variables without using 4th variable
#include
main()
{	int a, b, c;
	printf ("Enter values for a, b, and c : ");
	scanf ("%d %d %d", &a, &b, &c);
	a = a+b+c;
	c = a-(b+c);
	b = a-(b+c);
	a = a-(b+c);
	printf("a = %d, b = %d, C = %d \n", a, b, c);
}

4. WAP to calculate the hours, minutes and seconds by giving seconds as input.

//Program to convert seconds into hours, minutes and seconds
#include
main()
{	unsigned long int sec, hour, min;
	printf("Enter time in seconds : ");
	scanf ("%d", &sec);
        //There is a scope for simplifying and enhancing the logic
	hour = sec/3600;
	min = (sec/60)-(hour*60);
	sec -= (hour*3600)+(min*60);
	printf("Time = %d hour(s) %d min(s) %d sec(s)\n", hour, min, sec);
}

5. WAP to reverse a 3-digit number

/* Program to reverse a 3-digit number
    For Ex : If input - 123, output = 321    */
#include
main()
{	int num, a, b, c, rev;
	printf("Enter a 3-digit number : ");
	scanf("%d", &num);
	a = num%10;
	num/=10;
	b = num%10;
	num/=10;
	c = num;
	rev = a*100 + b*10 + c;
	printf ("The reverse of entered number is %d \n", rev);
}

6. WAP to perform flooring and ceiling operation on  a real number.

/*  Program to perform flooring and ceiling operation on a number without using inbulit function(s) */
#include
main()
{
	float num;
        int floor, ceil;
	printf ("Enter a real number : ");
	scanf ("%f", &num);
	floor = (int)num;
	ceil = floor + 1;
	printf ("Real number = %f", num);
        printf ("\nFloor = %d", floor);
        printf ("\nCeil = %d", ceil);
}

7. WAP to enter a character and display its ASCII equivalent in decimal and hexadecimal.

//Program to display the ASCII code of a character in decimal as well as hexadecimal
#include
main()
{	char ch;
	printf("Enter a Character : ");
	scanf("%c", &ch);
	printf("ASCII value of %c in decimal = %d \n", ch, ch);
	printf("ASCII value of %c in hexadecimal = %x \n", ch, ch);
}

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