IT Lesson

A bit more about conditions

What is expression?

Conclusion

Sample Program

/*Program to show discount*/
#include <stdio.h>

void main()
{
 float amnt,famnt,dis;
 printf("Enter the total amount
");
 scanf("%f",&amnt);
 famnt=amnt;

 if (amnt>2000)
 {
  printf("You are eligible for discount
");
  dis=0.1*amnt;
  famnt=famnt-dis;
 }
 printf("final amount is %f",famnt);
}

Check out this video for demo

Program for Analog Clock in C

/* Graphical Analog Clock designed in C*/
/*Note press ctrl+pause break to stop the clock while executing in TC*/

#include<stdio.h>
#include<graphics.h>
#include<stdlib.h>
#include<math.h>
#include<dos.h>
#include<time.h>

#define PI 3.147

void clockLayout();
void secHand();
void hrHand();
void minHand();
int maxx,maxy;

void main()
{
 int gdriver=DETECT,gmode,error;
 initgraph(&gdriver,&gmode,"c:\turboc3\bgi\");
 error=graphresult();
 if(error!=grOk)
 {
  printf("Error in graphics, code= %d",grapherrormsg(error));
  exit(0);
 }

 while(1)
 {
  clockLayout();
  secHand();
  minHand();
  hrHand();
  sleep(1);                /* pausing the outputscreen for 1 sec */
  cleardevice();           /* clearing the previous picture of clock */
 }
}

void clockLayout()
{
 int i,x,y,r;
 float j;
 maxx=getmaxx();
 maxy=getmaxy();

 for(i=1;i<5;i++)
 {                   /* printing a round ring with outer radius of 5 pixel */
  setcolor(YELLOW);
  circle(maxx/2,maxy/2,120-i);
 }

 pieslice(maxx/2,maxy/2,0,360,5);    /* displaying a circle in the middle of clock */
 x=maxx/2+100;y=maxy/2;
 r=100;
 setcolor(BLUE);

 for(j=PI/6;j<=(2*PI);j+=(PI/6))
 {    /* marking the hours for every 30 degrees */
  pieslice(x,y,0,360,4);
  x=(maxx/2)+r*cos(j);
  y=(maxy/2)+r*sin(j);
 }

 x=maxx/2+100;y=maxy/2;
 r=100;
 setcolor(RED);

 for(j=PI/30;j<=(2*PI);j+=(PI/30))
 {  /* marking the minutes for every 6 degrees */
  pieslice(x,y,0,360,2);
  x=(maxx/2)+r*cos(j);
  y=(maxy/2)+r*sin(j);
 }
}

void secHand()
{
 struct time t;
 int r=80,x=maxx/2,y=maxy/2,sec;
 float O;

 maxx=getmaxx();maxy=getmaxy();
 gettime(&t);                     /*getting the seconds in system clock */
 sec=t.ti_sec;
 O=sec*(PI/30)-(PI/2);           /* determining the angle of the line with respect to vertical */
 setcolor(YELLOW);
 line(maxx/2,maxy/2,x+r*cos(O),y+r*sin(O));
}

void hrHand()
{
 int r=50,hr,min;
 int x,y;
 struct time t;
 float O;

 maxx=getmaxx();
 maxy=getmaxy();
 x=maxx/2,y=maxy/2;
 gettime(&t);                     /*getting the seconds in system clock */
 hr=t.ti_hour;
 min=t.ti_min;

 /* determining the angle of the line with respect to vertical */
 if(hr<=12)O=(hr*(PI/6)-(PI/2))+((min/12)*(PI/30));
 if(hr>12) O=((hr-12)*(PI/6)-(PI/2))+((min/12)*(PI/30));
 setcolor(BLUE);
 line(maxx/2,maxy/2,x+r*cos(O),y+r*sin(O));
}

void minHand()
{
 int r=60,min;
 int x,y;
 float O;
 struct time t;
 maxx=getmaxx();
 maxy=getmaxy();
 x=maxx/2;
 y=maxy/2;
 gettime(&t);  /*getting the seconds in system clock */
 min=t.ti_min;
 O=(min*(PI/30)-(PI/2)); /* determining the angle of the line with respect to vertical */
 setcolor(RED);
 line(maxx/2,maxy/2,x+r*cos(O),y+r*sin(O));
}

do while loop in C

Flowchart of do while loop in C - Image Source

#include<stdio.h>

void main()
{
	do
	{
		printf("OMG its working!");
	}while(7>10);
}

Functions in C Programming

#include<stdio.h>

void firstfu();
void secondfu();
void thirdfu();
void fourthfu();


void main()
{
 printf(" Control is in main
");
 firstfu();
}

void firstfu()
{
 printf(" Now the control is in firstfu function
");
 thirdfu();
}

void secondfu()
{
 printf(" Now the control is in secondfu function
");
 fourthfu();
}

void thirdfu()
{
 printf(" Now the control is in thirdfu function 
");
 secondfu();
}

void fourthfu()
{
 printf(" Now the control is in fourthfu function 
");
}

• The program starts with main() function and it will print the message inside it. After that I have called the firstfu() function from main(). Remember here main() is calling function and firstfu() is called function.
• Now the control reaches to firstfu() function and the activity of main() function is suspended temporarily. Inside firstfu() function, printf() will print a message. Now I have called thirdfu() function. Remember here firstfu() is calling function and thirdfu() is called function
• Now the control reaches to the thirdfu() function and the activity of firstfu() function is suspended temporarily. And it will execute its printf() function. Now I have called the secondfu() function.
• Same thing will happened to the secondfu() function and it will call the fourthfu() function.
• Now the printf() statement will be executed inside the fourthfu() function. As there is no further call to other function there. So the control will goes back to the calling function. Calling function of fourthfu() is secondfu().
• No more statements is left in secondfu(). So the control will reach to the calling function. thirdfu() is the calling function of secondf().
• Same execution will be done for all of them. And the control will reach to the main() function again. Now no statement is left in main() function, so the program will be terminated.

Structure in C

Accessing Elements of Structure

//structure definition
struct student
{
 char name[10];
 int roll;
 int marks;
}s1;

struct student s1={"Rishi",4,56}; //storing values

//accessing structure elements
printf("%s%d%d",s1.name,s1.roll,s1.marks);

Memory Allocation of Structure Elements

Array of Structure

#include<stdio.h>

int main() 
{  
 struct library
 {
  char lang[10];
  int pages;
  char name[20];
 };
 
 struct library lib[3];
 int i;
 
 for(i=0;i<3;i++)  
 {   
  printf("
Enter language, pages and name
");   
  scanf("%s%d%s",&lib[i].lang,&lib[i].pages,&lib[i].name);  
 }  

 for(i=0;i<3;i++)     
  printf ( "
%s	%d	%s
",lib[i].lang,lib[i].pages,lib[i].name); 
 
 return 0;
}