Introduction to C - Applications solved

1) Write a program that displays the text: "Hello!".

#include<stdio.h>
void main()
{
	printf("Hello!");
 	getchar();
}

2) ) Write a program that displays the text "Hello!", so that the message must be sent through a variable of a type adapted correctly.

#include<stdio.h>
void main()
{
	char a[]="Hello!";
	printf("%s",a);
	getchar();
}

3) Write a program that displays the text "Hello!" so that the message appears to be sent through a variable of a type well suited to other types of memory.

#include<stdio.h>
void main()
{
	char* a="Hello!";
	printf("%s",a);
	getchar();
}

4) Write a program that displays the text "Hello!" so that the display is made by means of a user-defined function.

#include<stdio.h>
void display()
{
	printf("Hello!");
}
 void main()
{
	display();
	getchar();
}

5) Write a program that displays the text "Hello!" so that the display is carried out through a universal function, with the possibility of transmission of the chain parameter.

#include<stdio.h>
void display(char a[])
{
printf("%s", a);
}
void main()
{
	display("Hello!");
	getchar();
}

6) Write a program that displays the text "Hello!" so that the display is achieved by a universal function, with the possibility of transmission of the string parameter, a different kind of writing.

#include<stdio.h>
void display(char* a)
{
	printf("%s", a);
}
void main()
{
	display("Hello!");
		getchar();
}

7) Write a program to enter the desired string from the keyboard, then displays it on the screen.

#include<stdio.h>
void main()
{
	char* a;
	printf("Enter the string from the keyboard:");
	scanf("%s",a);
	printf(a);
	getchar();
}

8) Write a program that introduced from the keyboard the desired string, then it displays on the screen (other than the above version).

#include<stdio.h>
void main()
{
	char* a;
	printf("Enter the string from the keyboard:");
	gets(a);
	printf(a);
	getchar();
}

9) Calculate the sum of the integers as follows: given two values directly in the programs stored in two memory locations and calculate their sum.

#include<stdio.h>
void main()
{
	int a=3, b=7, c;
	c=a+b;
	printf("The sum of two numbers is: %d\n", c);
	getchar();
}

10) Calculate the sum of integers as follows: read two numbers from the keyboard and calculate their sum.

#include<stdio.h>
void main()
{
	int a,b;
	printf("Enter a=");
	scanf("%d", &a);
	printf("Enter b=");
	scanf("%d", &b);
	printf("Sum a+b=%d\n", a+b);
 
	getchar();
	int k;
	scanf("%d", &k);
}

11) Calculate the sum of integers as follows: read two numbers from the keyboard and calculate their sum and the result is obtained by means of a variable.

#include<stdio.h>
void main()
{
	int a,b;
	printf("Enter a:");
	scanf("%d", &a);
	printf("Enter b:");
	scanf("%d", &b);
	int c;
	c=a+b;
	printf("a+b=%d\n", c); 
 
	getchar();
	int k;
	scanf("%d",k);
}

12) Calculate the sum of integers as follows: write a function that will sum two integers.

#include<stdio.h>
int sum (int x, int y)
{
	int s;
	s=x+y;
	return s;
}
void main()
{
	int a,b;
	printf("Enter a: "); scanf("%d",&a);
	printf("Enter b: "); scanf("%d",&b);
 	int c;
	c=sum(a,b);
	printf("Sum is: %d\n",c);
 
 	getchar();
	int k;
	scanf("%d", k);
}

13) Calculate the sum of integers as follows: read two nombers from the keyboard and calculate their sum. Will write a function sum of two integers. The function returns the result by line parameters.

#include<stdio.h>
void sum(int x,int y,int* s)
{
	*s=x+y;
}
void main()
{
	int a,b;
	printf("Enter a: "); scanf("%d",&a);
	printf("Enter b: "); scanf("%d",&b);
	int c;
	sum(a,b,&c);
	printf("Sum is: %d\n",c); 
 
	getchar();
	int k;
	scanf("%d", k);
}

14) You have to write a function that calculates the arithmetic average of two integers.

#include<stdio.h>
int average (int x, int y)
{
	int av;
	av=(x+y)/2;
	return av;
} 
void main ()
{
	int a, b;
	printf("Enter a: ");
	scanf("%d", &a);
	printf("Enter b: ");
	scanf("%d", &b);
 
	int m;
	m=average(a,b);
	printf("Arithmetic average is: %d\n", m);
 
	getchar();
	int k;
	scanf("%d", k);
}

15) Calculate the arithmetic average of two integers, as follows: read two numbers from the keyboard and their arithmetic mean is calculated. Will write a function that calculates the average of two integers. The function returns the result of the line parameters.

#include<stdio.h>
void average(int a, int b, int* c)
{
	*c=(a+b)/2;
}
void main()
{
	int x,y;
	printf("Enter x: ");
	scanf("%d", &x);
	printf("Enter y: ");
	scanf("%d", &y);
 	int z;
	average(x,y,&z);
	printf("Arithmetic average is: %d", z);
 
 	getchar();
	int k;
	scanf("%d", k);
}

16) Calculate the arithmetic average of two integers.

#include<stdio.h>
void main()
{
	int a,b;
	printf("Enter a: ");
	scanf("%d", &a);
	printf("Enter b: ");
	scanf("%d", &b);
 
	int s=a+b;
	float m=(float)s/2;
 
	printf("Sum is: %d\n", s);
	printf("Arithmetic average is: %.2f", m);
 
	getchar();
	int k;
	scanf("%d", k);
}

17) Calculate 2 to the power n, where n is an integer read from the keyboard.

#include<stdio.h>
void main()
{
	int n;
	printf("Enter n:");
	scanf("%d", &n);
	int p=1;
	printf("2^%d=%d",n,p=(p<<n));
 
	//The shift operators shift their first operand left (<<) 
	//or right (>>) by the number of positions the second operand specifies
	getchar();
	int k;
	scanf("%d", k);
}

18) It is read a decimal number and one in hexa up to 4 digits each and are required to display those values in the systems numbered 10, 8 and 16.

#include<stdio.h>
void main()
{
	unsigned int a,b;
	printf("Enter a decimal integer: ");
	scanf("%d",&a);
	printf("Enter a hexadecimal integer: ");
	scanf("%x",&b);
	printf("\ndecimal integer:\tBase 10: %u\tBase 8: %#o\tBase 16: %#X",a,a,a);
	printf("\nhexadecimal integer:\tBase 10: %u\tBase 8: %#o\tBase 16: %#X",b,b,b); 
 
	getchar();
	int k;
	scanf("%d", k);
}

19) Make a routine that uses increment (decrement) after and prefixed.

#include<stdio.h>
void main()
{
	int val=1;
 
	printf("using postfix %d\n", val++);
	printf("use after incrementing %d\n", val);
 
	
	printf("use prefix%d\n", ++val);
	printf("use after incrementing %d\n", val);
 
	
	printf("use postfix %d\n", val--);
	printf("use after decrement %d\n", val);
 
	
	printf("use prefix %d\n", --val);
	printf("use after decrement %d\n", val);
 
	getchar();
	int k;
	scanf("%d", k);
}

20) Execute a routine that performs work on bits.

#include<stdio.h>
void main()
{
	unsigned int a=5;
	const int b=7;
	printf("%d <or on bits> %d is %d\n", a,b, a|b);
	printf("%d <and on bits> %d is %d\n", a,b, a&b);
	printf("%d <or exclusively on bits> %d is %d\n", a,b, a^b);
	printf("5 <complemented on bits> is %u variable is on %u bytes\n",~a,sizeof(a));
 
 	getchar();
	int k;
	scanf("%d", k);
}

21) Write a program that reads the value of x, positive, displays the values of x, [x], {x}, calculates and displays the value of the following expression : 5*x*[x]-3*{x}+15.

#include<stdio.h>
void main()
{
	double x;
	int y;		//for the entire
	double z; 	//for the decimal
	
	printf("Enter x:");
	scanf("%lf", &x);
 
	printf("x= %g\t", x);
	printf("[x]= %d\t", y=x);
	printf("{x}= %f\t", z=x-y);
 
	printf("e=%g\n", 5*x*x-3*z+15);
 
	getchar();
	int k;
	scanf("%d", k);
}

22) Determine the maximum and minimum of two integers.

#define max(x,y) x>y?x:y //#define=give meaningful name to a constant from program
#define min(x,y) x<y?x:y
#include<stdio.h>
void main()
{
	int x,y;
	printf("Enter x: ");
	scanf("%d", &x);
	printf("Enter y: ");
	scanf("%d", &y);
 
	printf("\n\Max is: %d\n", max(x,y));
	printf("\n\Min is: %d\n", min(x,y));
 
	getchar();
	int k;
	scanf("%d", k);
}

23) It is given three real nombers a, b, c. They can represent the lengths of the sides of a triangle?

#include<stdio.h>
void main()
{
	float a,b,c;
	printf("Give side lengths:\n");
	scanf("%f %f %f", &a, &b, &c);
 
	(a>=0 && b>=0 && c>=0 && a<b+c && b<a+c && c<a+b)?printf("\t %4.2f, %4.2f si %4.2f triangle formed.",a,b,c):printf ("\t Not form triangle.");
 
	getchar();
	int k;
	scanf("%d", k);
}

24) Write a program that reads n integer and displays the value of the expression: n / (n +1) with 15 decimal places.

#include<stdio.h>
void main()
{
	int n;
	printf("Enter n:");
	scanf("%d", &n);
	float e;
	e=(float)n/(n+1);
	printf("Expression value is: %.15f", e);
 
	getchar();
	int k;
	scanf("%d", k);
}

25) Determine the maximum and the minimum of two integers, using macros.

#define max(x,y) x>y?x:y
#define min(x,y) x<y?x:y
#include<stdio.h> 
void main()
{
	int x, y;
	printf( "Enter x and y:\n");
	scanf("%d %d", &x, &y);
	printf("\n\tMax is: %d", max(x,y));
	printf("\n\tMin is: %d", min(x,y));
 
	getchar();
	int k;
	scanf("%d", k);
}

26) Write a program to calculate the number of feet in a yard, where he yag g chickens, p cats and a man.

#include<stdio.h> 
void main()
{
	int g,p;
	printf("\nEnter the number of chickens:" );
	scanf("%d", &g);
 
	printf("\nEnter the number of cats:" );
	scanf("%d", &p);
 
	printf("\n\tNumber of legs is: %d", g*2+p*4+2);
	 
	getchar();
	int k;
	scanf("%d", k);
}

27) Use conditional operator to check if x is a real number in [a, b), where a and b are given by the keyboard.

#include<stdio.h> 
void main()
{
 	float x;
	printf("Enter x:");
	scanf("%f", &x);
 
	int a,b;
	printf("Enter a: ");
	scanf("%d", &a);
	printf("Enter b: ");
	scanf("%d", &b);
 
	(x>=a&&x<b) ? printf("\n\tX is in the interval[%d %d)", a,b) : printf("\n\tX not in the interval [%d %d)", a,b);
 
	getchar();
	int k;
	scanf("%d", k);
}

28) Write a program that reads the value of the variable x and displays the value of the function f(x) :

      |3*x*x+7*x-10  x<0
f(x)= |2             x=0
      |4*x*x         x>0

#include<stdio.h>
void main()
{
 
	int x;
	printf("Enter x:");
	scanf("%d", &x);
 
	if(x==0)
	printf("F(x)=2");
	else
	if(x<0)
	printf("F(x)=%d",3*x*x+7*x-10);
	else
	printf("F(x)=%d",4*x*x);
 
	getchar();
	int k;
	scanf("%d", k);
}