Thread: array and loop help

problem is that if the user enters a number over 10, it outputs the error but then runs directly into prompting for radi, it shouldnt do this. instead i need it to ask to imput a number of circles again.
also, its not storing the radi into an array of "circleno" (the number the user entered for how many circles to calculate) length. it takes the last radi entered and runs it through the loop to calculate the circumference and area. then prints the same answers for all circles.

I cleaned up your code a bit to use some precison specifiers and a simple while loop. When in doubt about why your code is acting up, a simple print statement can go a long way. compile and run it and see what value circleno has.

Code:

#include <stdio.h>
#define PI 3.14159265
#define CONSTANT 10
int main (void)
{
	int circleno,i, j;
	/*circleno < CONSTANT initially so while block is evaluated first*/
  while ( circleno > CONSTANT){
        printf("Please enter the number of circles (max = 10):");
       	scanf("%i", &circleno);
  }
         
	
	float radius[circleno], circumference[circleno], area[circleno];
		
	for ( j = 0; j < circleno; j++ ){
      printf("Enter the radius for circle #%i:\n", j);
      scanf("%f", &radius[circleno]);
      
    printf("circleno is: %d\n", circleno);
     
      
      circumference[circleno] = 2*PI*radius[circleno];
      
      area[circleno] = PI* (radius[circleno] *radius[circleno]);
	}
  
  printf("radius     circumference     area     \n");
  printf("======================================\n");
  
  /*notice anything?? */
  printf("circle no: %d\n", circleno);
  
  for ( i = 0; i < circleno; i++ ){
      printf("%.2f  %15.2f  %15.2f\n", radius[circleno], circumference[circleno], 
      area[circleno]);
	}

return 0;
}

problem is that if the user enters a number over 10, it outputs the error but then runs directly into prompting for radi, it shouldnt do this. instead i need it to ask to imput a number of circles again.
also, its not storing the radi into an array of "circleno" (the number the user entered for how many circles to calculate) length. it takes the last radi entered and runs it through the loop to calculate the circumference and area. then prints the same answers for all circles.

i've modified ur code and it works.

Code:

#include <stdio.h>
#include<conio.h>
#include<stdlib.h>
#define PI 3.14159265
#define CONSTANT 10
int main (void)
{
	int circleno;
	int j;
	int i;
	
	printf("Please enter the number of circles (max = 10):\n");
	scanf("%d", &circleno);
	
	float radius[10];//while declaring array it should have constant size
	float circumference[10];
	float area[10];
	
	if ( circleno > CONSTANT ){
		printf("Error -> %d circles is to many. Please try again:\n", circleno );
		exit(0);}
		else
			for ( j = 1; j <= circleno; ++j ) {
				printf("Enter the radius for circle #%d:\n", j);
				scanf("%f", &radius[j]);//radius[circleno] is the radius of last circle which gets stored each time for every circle,thus radius[j] is used
				circumference[j] = 2*PI*radius[j];//same reason as above				
area[j] = PI*radius[j]*radius[j];//same reason as above
			}
			printf("radius     circumference     area     \n");
			printf("======================================\n");
			for ( i = 1; i <= circleno; ++i ) {
				printf("%f         %f                %f       \n", radius[i], circumference[i], area[i]);
			}
			getch();
			return 0;
}