Basic Program of C

  

 Source code :

 1.To display two number :

#include<stdio.h>
#include<conio.h>
int main()
{
    int a,b;
printf("Enter the number\n");

scanf("%d %d",&a,&b);

printf("The numbers are %d %d",a,b);
getch();
}
Output:

Here we use & to address the  the variable a,b.
int a,b means a and b are integer.

2, Calculation of Simple Interest :

#include<stdio.h>

#include<conio.h>

int main()

{
    int p,t,r,si;
printf("Enter the principle,time,rate\n");
scanf("%d %d %d",&p,&t,&r);
si=p*t*r/100;

printf("The si is %d",si);

getch();
}

Output:

Here we  use 3 %d  because we have to give the value of 3 numbers and we have to find the value of  one  si so the is 1 %d at the last printf before getch.
And * means multiplication.

Hope you have understood.


3. Program to add two numbers :


#include<stdio.h>
#include<conio.h>
int main()
{
    int a,b,sum;
printf("Enter the two number\n");
scanf("%d %d",&a,&b);

sum=a+b;
printf("The sum  of two number is %d",sum);
getch();
}
Output:

4. Program to find area and circumference of circle :

#include<stdio.h>
#include<conio.h>
#include<math.h>
int main()
{
    int A,C,r;
printf("Enter the radius\n");
scanf("%d",&r);
A=3.14*pow(r,2);;
C=2*3.14*r;
printf("The area and circumference is %d %d",A,C);
getch();
}

Here we use #include<math.h> because we know the area of circle is pi(3.14)*r*r
so for easy or for terms having their power greater than 1 we can write #include<math.h>.
Also there is 2 %d at last printf as we have to give the output of two terms A and C .
Or we can  simply write

#include<stdio.h>
#include<conio.h>
int main()
{
    int A,C,r;
printf("Enter the radius\n");
scanf("%d",&r);
A=3.14*r*r; You can notice here we have not used pow
C=2*3.14*r;
printf("The area and circumference is %d %d",A,C);
getch();
}

Output:

Here we have not obtained decimal form as we used interger but if we used float we can obtained decimal form i.e:

#include<stdio.h>
#include<conio.h>
int main()
{
    int r;
    float A,C;
printf("Enter the radius\n");
scanf("%d",&r);
A=3.14*r*r;

C=2*3.14*r;
printf("The area and circumference is %f %f",A,C);
getch();
}


Output:

5. Program to convert Celsius into Farenheit

#include<stdio.h.>
#include<conio.h>
void main()
 {
float C,F;

printf("Enter the temperature in celsius\n");

scanf("%f",&C);

F=1.8*C+32;
printf("The req Farenheit is %f",F);
getch();
}

Output:

Float gives the output after the decimal upto 6 digits .eg:4.000897