C - Exercise 4

In this exercise section of the tutorial we will write some C program.

Write a program in C to print "Hello World" n times where the value of n will be provided by the user and condition is 1 <= n <= 10

So, we first have to take the value of n (integer) from the user as input.

Then, we have to check if the value of n satisfies the condition 1 <= n <= 10 i.e., n must be greater than or equal to 1 and n must be less than or equal to 10. So, n can take any value from 1 to 10.

Lets write the C program.

/**
 * file: hello_world.c
 * author: yusuf shakeel
 * date: 2010-12-15
 * description: hello world program
 */

#include <stdio.h>
int main(void)
{
  //variable
  int n, i;
  
  //user input
  printf("Enter value of n between 1 to 10: ");
  scanf("%d", &n);
  
  //check condition
  if (n >= 1 && n <= 10) {
    //print Hello World
    for (i = 1; i <= n; i++) {
      printf("Hello World\n");
    }
  }
  else {
    printf("Error: Value of n must be between 1 to 10.\n");
  }
  
  printf("End of code\n");
  return 0;
}

Output

Enter value of n between 1 to 10: 5
Hello World
Hello World
Hello World
Hello World
Hello World
End of code

If we enter some other value of n then we will get an error message.

Enter value of n between 1 to 10: 100
Error: Value of n must be between 1 to 10.
End of code

Write a program in C to find the volume of a sphere where radius is provided by the user as input

The formula to find the volume of a sphere is given below.

V = (4πr3)/3

where,
V = Volume of the sphere
r = Radius of the sphere

To solve this lets take the PI value as 3.14 so, we can re-write the expression as follows

V = (4 * PI * r * r * r) / 3

where,
V = Volume of the sphere
PI = 3.14 approx. value of π
r = Radius of the sphere

Lets write the C program.

/**
 * file: sphere_volume.c
 * author: yusuf shakeel
 * date: 2010-12-20
 * description: volume of sphere program
 */

#include <stdio.h>

#define PI 3.14

int main(void)
{
  //variable
  float r, volume;
  
  //user input
  printf("Enter radius: ");
  scanf("%f", &r);
  
  //compute
  volume = (4 * PI * r * r * r) / 3;
  
  //output
  printf("Volume: %f\n", volume);
  
  printf("End of code\n");
  return 0;
}

Output

Enter radius: 7
Volume: 1436.026611
End of code

Write a program in C to print the following pattern using nested for loop

Pattern:
*
* *
* * *
* * * *
* * * * *
* * * * * *

Looking at the above pattern we can tell that there are 6 rows and 6 columns.

So, we can write the first for loop for the rows and the second for loop for the column.

Another thing to note is that:
1st row contains 1 star
2nd row contains 2 stars
3rd row contains 3 stars
and so on...

Lets write the program in C.

/**
 * file: pattern.c
 * author: yusuf shakeel
 * date: 2010-12-10
 * description: patterns program
 */

#include <stdio.h>
int main(void)
{
  //variables
  int r, c;
  
  for (r = 1; r <= 6; r++) {
    for (c = 1; c <= r; c++) {
      printf("* ");
    }
    printf("\n");
  }
  
  printf("End of code\n");
  return 0;
}

Output

* 
* * 
* * * 
* * * * 
* * * * * 
* * * * * * 
End of code