Here you will find all solution of Let Us C book.

Let_us_c.c

/*
  Author : Rohit Singh
  Purpose: To implement all exercise of let us c book.
*/

/*
  ######################################### Let us C Chapter 1 Solution #########################################
  _______________________________________________________________________________________________________________
*/

/*
	Ramesh’s basic salary is input through the keyboard. His dearness
	allowance is 40% of basic salary, and house rent allowance is 20% of
	basic salary. Write a program to calculate his gross salary.
*/

#include<stdio.h>
int main()
{
	int basic_salary;
	printf("Enter Ramesh's Basic Salary : ");
	scanf("%d",&basic_salary);
	int dearness_allowance = ( basic_salary * 40 ) / 100;
	int house_rent = ( basic_salary * 20 ) / 100;
	int gross_salary = basic_salary + dearness_allowance + house_rent;
	printf("Ramesh's Gross salary is %d\n",gross_salary);
	return 0;
}

/*
	The distance between two cities (in km.) is input through the
	keyboard. Write a program to convert and print this distance in
	meters, feet, inches and centimeters.
*/

#include<stdio.h>
int main()
{
	int distance;
	printf("Enter distance between two cities in km : ");
	scanf("%d",&distance);
	printf("Distance ( meter ) = %d\n",distance * 1000);
	printf("Distance ( foot ) = %.2f\n",distance * 3280.84);
	printf("Distance ( inches ) = %.2f\n",distance * 39370.1);
	printf("Distance ( centimeters ) = %.2f\n",distance * 100000.054);
	return 0;
}

/*
	If the marks obtained by a student in five different subjects are
	input through the keyboard, write a program to find out the
	aggregate marks and percentage marks obtained by the student.
	Assume that the maximum marks that can be obtained by a student
	in each subject is 100.
*/

#include<stdio.h>

int main()
{
	int marks[5],i;
	int sum = 0;
	for(i = 0; i < 5; i++ )
	{
		printf("Enter the marks obtain in %d subject : ",i+1);
		scanf("%d",&marks[i]);
		sum += marks[i];
	}
	printf("Total marks obtain = %d\n",sum);
	int percentage = (sum * 100) / 500;
	printf("Percentage obtained = %d\n",percentage);
	return 0;
}

/*
	Temperature of a city in Fahrenheit degrees is input through the
	keyboard. Write a program to convert this temperature into
	Centigrade degrees.
*/

#include<stdio.h>

int main(int argc, char const *argv[])
{
	int fahrenheit;
	printf("Enter city's tempreture in fahrenheit :");
	scanf("%d",&fahrenheit);
	float centigrade = ( fahrenheit - 32 ) * ( 5.0 / 9.0 );
	printf("City's tempreture is %.1f centigrade",centigrade);
	return 0;
}

/*
	The length and breadth of a rectangle and radius of a circle are
	input through the keyboard. Write a program to calculate the area
	and perimeter of the rectangle, and the area and circumference of
	the circle.
*/

#include<stdio.h>
#define PI 3.14

int main(int argc, char const *argv[])
{
	int length,breath;
	float radius;
	printf("Enter the length of rectangle : ");
	scanf("%d",&length);
	printf("Enter the breath of rectangle : ");
	scanf("%d",&breath);
	printf("Enter the radius of circle : ");
	scanf("%f",&radius);
	int  area = length * breath;
	int perimeter = 2 * length * breath;
	printf("Area of the rectangle is %d & perimeter of the rectangle is %d\n",area,perimeter);
	printf("Area of the circle is %.2f & circumference is %.2f\n",(PI * radius * radius),( 2 * PI * radius));
	return 0;
}

/*
	Paper of size A0 has dimensions 1189 mm x 841 mm. Each
	subsequent size A(n) is defined as A(n-1) cut in half parallel to its
	shorter sides. Thus paper of size A1 would have dimensions 841
	mm x 594 mm. Write a program to calculate and print paper sizes
	A0, A1, A2, ... A8.
*/

#include<stdio.h>

int main(int argc, char const *argv[])
{

    int i, width=841, height=1189, temp;
	for(i = 0; i < 9; i++)
	{
		printf("\n A%d: %d x %d", i, width, height);
		temp = height;
		height = width;
		width = temp / 2;
	}
	return 0;
}