What type to use

I am creating a program. Now i have to get the user to input the value in the format "f1.5", "f6", "f5.6", etc etc...
What type can i use for those?

Thanks

What's wrong with strings?

hmmm u can use string? ok cool, i just started C. Thanks

What about if i want to display an answer as 1/200. Is it possible to be displayed like that and not in decimal?

Erm, well, you can't use std::string in C, you'll have to use char arrays.
Within a char array, you can have "1/200", but you won't be able to do calculations with it.
There's also (to my knowledge) no library function which will take a decimal number and find it's fraction representation (Now, *that* would be a good homework task!)

QuantumPete

haha very true pete.

Code:

---

#include <stdio.h>
#include <string.h>
int main(int argc, char ** argv)

{

FILE * output = stdout;
FILE * input = stdin;

float exposureTime;
char aperture[5];

 
        fprintf(output,"Please enter exposure time: "); fflush(output);
 
        fscanf(input,"&#37;f",&exposureTime); 

          fprintf(output,"Please enter aperture value: "); fflush(output);
 
        fscanf(input,"%s",&aperture);
   
          if(strcmp (aperture == "f2" || "f3" || "f6")
        {
        printf("ERROR\n");   
        }

        else
        { 
        fprintf(output,"\n");
        fprintf(output,"    Camera Test Code\n");
            fprintf(output,"~~~~~~~~~~~~~~~~~~~~~~~~~~\n");
            fprintf(output,"The exposure time is %.2f\n",exposureTime);
            fprintf(output,"The aperture value is %s\n",aperture);
        fprintf(output,"~~~~~~~~~~~~~~~~~~~~~~~~~~\n");
        }
}

---

Does the strcmp look ok?

No, it doesn't.

umm...no.

strcmp takes two string and returns 0 if they're equal.

So :

strcmp("foo", "foo") will return 0.
strcmp("foo","bar") will not return 0.

Therefore, you'd probably want something like :

strcmp(aperture,"f2") == 0 || strcmp(aperture,"f3") == 0 || ...

perhaps you should change those fprintf functions to standard output function and input function for i/o operation as show below

Code:

---

printf("Please enter exposure time: ");
//fprintf(output,"Please enter exposure time: "); fflush(output);
fscanf(input,"%f",&exposureTime); 

printf("Please enter aperture value: ");
//fprintf(output,"Please enter aperture value: "); fflush(output);
fgets(aperture, sizeof(aperture), stdin);
//fscanf(input,"%s",&aperture);

---

ssharish2005

alright am just gonna have a read up on the fgets, never seen it before

could someone briefly explain what the fflush(output); means?
thanks

Quote:

---

Originally Posted by taurus

could someone briefly explain what the fflush(output); means?
thanks

---

It is a call that "outputs" any pending data from the buffer that is used to optimize the output to files - because it's "expensive" to call the low-level write routines for one or a few characters at a time, it is better to store the data in a buffer (essentially an array), so that when there's little bits of data printed out, it's stored in this buffer, rather than calling the OS low-level write routine for each one of those. A bit like using a bag to carry potatos from your the shop, rather than carrying one or two potato(s) at a time to get them to your car.

--
Mats

briefly: When you printf, the output isn't send to your screen immediatly, but is buffered (to save time and resources). To force this buffer to be emptied (flushed) you run fflush(). This will print any outstanding output onto your screen.

QuantumPete