validate numerical entry

When I strip those // comments, your code compiles with just a few warnings.

Code:

---

nocompile2.c: In function ‘main’:
nocompile2.c:41: warning: ISO C90 forbids mixed declarations and code
nocompile2.c:60: warning: control reaches end of non-void function
nocompile2.c: At top level:
nocompile2.c:36: warning: unused parameter ‘argc’
nocompile2.c:36: warning: unused parameter ‘argv’

---

In other words, you're declaring a variable in the middle of a block, and main() takes two parameters that you're not using and main() isn't returning anything. Quite minor.

You want me to do the surgery? Okay, fine.

Code:

---

int main(int argc, char * argv[])
{
output = stdout;
input = stdin;

int i;
float array[SIZE];

        for(i=0; i<SIZE; i++)
        {
            while(1) {
                fprintf(output,"Enter value &#37;i: ",i);
                if(scanf("%lf", &array[i]) == 1) break;
                while(getchar() != '\n');
            }
        }

        fprintf(output,"\n");
        fprintf(output,"Your values you entered are as follows:\n");
        display(array);
        fprintf(output,"The maximum value entered is:\n");       
        fprintf(output,"%.4e\n",max(array));
}

---

That wasn't hard, was it? ;)

ah thanks so much.
can i take it that 'break' means leave loop?

also is there a way you could briefly explain that, i understand it but not sure.
this is what i think,

the while(1) is infinite like the for(;; ) you said.
then 'if' its a number it is fine and breaks out to the next input.
now the getchar im a bit confused?

Quote:

---

can i take it that 'break' means leave loop?

---

Yep, and continue means skip the rest of the loop and start it from the beginning again. http://www.cprogramming.com/tutorial/c/lesson3.html

Quote:

---

now the getchar im a bit confused?

---

It's just like

Code:

---

int c;

do {
    c = getchar();
} while(c != '\n');

---

It just ignores all characters up to and including a newline.

ahh right i see, thanks

I usually go for "read user input as a string and attempt to convert" to integral or floating point.

i guess yea that could also work

got a problem, when i enter negative values like -0.003, -0.0002, -0.1 etc etc it doesnt work correctly with my code, what do i do???

thanks

Quote:

---

Originally Posted by taurus

got a problem, when i enter negative values like -0.003, -0.0002, -0.1 etc etc it doesnt work correctly with my code, what do i do???

---

Post the relevant code with your query?

Code:

---

#include <stdio.h>
#define SIZE 10

FILE * output =NULL;
FILE * input =NULL;

// Procedure
void display(float array[SIZE])
{
int i;
        for(i=0; i<SIZE; i++)
        {
                fprintf(output,"%.4f ",array[i]);// Display array
        }
        fprintf(output,"\n");
}

// Function
float max(float array[SIZE])
{
        int i;
        float max=0.0f;
        for(i=0; i<SIZE; i++)
        {
                // For each number, the number is compared with max and if > it stores as max
                if(array[i]>max)
                {
                        max=array[i];
                }
        }
        // Return the maximum integer
        return max;
}

int main(int argc, char * argv[])
{
output = stdout;
input = stdin;

int i;
float array[SIZE];

        for(i=0; i<SIZE; i++)
        {
            while(1) {
                fprintf(output,"Enter value %i: ",i);
                if(scanf("%lf", &array[i]) == 1) break;
                while(getchar() != '\n');
            }
        }

        fprintf(output,"\n");
        fprintf(output,"Your values you entered are as follows:\n");
        display(array);
        fprintf(output,"The maximum value entered is:\n");       
        fprintf(output,"%.4e\n",max(array));
}

---

now when i put in very small NEGATIVE numbers it doenst display the correct max?

Code:

---

                if(scanf("%lf", &array[i]) == 1) break;

---

Quote:

---

../main.c:47: warning: double format, float arg (arg 2)

---

Does it help if you correct that?

ok i changed that to 'f'

the problem is if i have entered small values like -0.003 etc etc with the negative, how can i find the max.

i tried this
unsigned float max = -0.0000009 but that doesnt work, what can i do?

If you don't want the max to be at least as high as zero, don't do this.

Code:

---

float max=0.0f;

---

Start with the first element of the array, or start with the smallest possible float -- available in a standard header file -- FLT_MIN.

haha yea i found the problem, was doing it correctly all the time, i was just thinking -0.1 is bigger than -0.0008 which is wrong