Thread: true/false

i am trying to make the following code work, but it always returns 0.
what am i doing wrong?

Code:

#include <stdio.h>
#include <stdlib.h>

#define TRUE 1
#define FALSE 0

#define SIZE 5

//prototype
int isValid(input);


main(){

	int values [SIZE]={0};
	int count;
	int i;
	int valid;
	int result;
	count=0;
	result=0;



	for (i=0; i<SIZE; i++){
		printf("Enter an integer (50-100):\n");
		scanf("%i",&values[i]);

		valid =isValid(values[i]);
		//unique=isUnique();
		printf("%i\n",result);
	}

	system("pause");
}

int isValid(int input){
	int result;
	if (input>=50 && input <=100)
		result= TRUE;

	else 
		result= FALSE;
	return result;
}

thank you
i am still very new to this so it's taking me a little longer to figure certain things out.

also i am trying to figure out how to make the program run until it has 5 valid numbers
how would i go about doing that

Code:

int main(){

   int values [SIZE]={0};
   int i = 0;

   while (i < SIZE) {
      printf("Enter an integer (50-100): ");
      scanf("%i",&values[i]);

      if (isValid(values[i]))
         ++i;
      else
         printf("Invalid input\n");
   }

   for (i = 0; i < SIZE; ++i)
   {
      printf("Result %d: %d\n", i, values[i]);
   }

   getchar();

   return 0;
}

if i put that in the bottom part of the program wouldnt that assume i to be a different variable

rags_to_riches i know how to make the program work that way, but for my assignmen we need to make two seperate functions so i am not able to do it the way that you did it.

Originally Posted by vart

one possible way - when entered number is not valid - decrease i

Code:

valid =isValid(values[i]);
if(!valid)
   i--;

That won't work when i is zero.

Maybe loop until you get 5 valids. You'd need a counter for the valids.

In order to make sure you have 5 valid numbers try something like this:

Code:

      int valid; 
      for (i=0; i<SIZE; i++){
		printf("Enter an integer (50-100):\n");
                valid = getValid();
                values[i] = valid;
	}

int getValid(){
    int retNum;
    
   scanf("&#37;d",&retNum);
   while(retNum < 50 || retNum > 100){
      printf("Enter a valid number: ");
      scanf("%d",&retNum);
   }
   return retNum;
}

-Dustin
http://www.theCprogrammer.com

Originally Posted by vart

And why not? What is so different about 0?

If i is zero and the array element at i is not valid, i gets decreased to -1. I'm not exactly sure what happens then. Since i is out of bounds of the loop parameters does the loop exit? If the loop doesn't exit it would try to access the array element at -1 index. Not good.

Originally Posted by vart

there is no such thing as bounds of loop parameter. There is loop condition that is checked before loop is entered

Code:

for(i=0;i<10;i++)
{
   i--;
}

is equivalent to

Code:

i=0;
while(i<10)
{
   i--;
   i++;
}

so it will not exit only due to i somethere in the loop getting to be negative

Thats what I thought, but wasn't sure. So i would be -1 and it would try to access the array. That would be attempting array access with an out of bounds index.