Disk IP/OP

Help........! I think writing a program that read and write datas from a file and onto another file is quite complicated. I dun know what to do. Can anyone please explain the following:

write a c program to determine the shortest, longest side of a triangle and its perimeter and area . Its sides are 4,6,10 which is stored onto a file call sides.txt. Then print their values to a new file.

What should I do?

Help...!

You should try first then post the code when you have trouble and then be happy if someone helps with just a small part of it.

I did try. However, I manage to get the program done a moment ago. But I dun know how to find the area. Can any one help? Also, is my step too long? Is there any shortest methods? This question is killing me for a few days .

I tried to post but window prompted: Pls use code tags to post code containing and . How to post? What code tags??

I did try. However, I manage to get the program done a moment ago. But I dun know how to find the area. Can any one help? Also, is my step too long? Is there any shortest methods? This question is killing me for a few days .

Hey I manage to post it in . Dun know why initially cannot. Anyway , pls advise.



#include <stdio.h>
#include <math.h>

int main(void)
{
int i, a[3];
FILE *input;
void shortest (int []);
void longest (int []);
void peri_area (int []);

input = fopen("sides.txt", "r");
if (input==NULL)
{
printf("Error!\n");
return 0;
}

for (i=0;i<3;i++)
fscanf(input, "%d", &a[i]);

shortest (a);
longest (a);
peri_area (a);

fclose(input);
return 0;
}

void shortest (int a[])
{
FILE *output=fopen("shortest.txt", "w");
int i, shortest=a[0];
for (i=0;i<3;i++){
if ( a[i]<shortest)
shortest = a[i];
}
fprintf(output, "%s%d", "\nShortest side is ", shortest);
fclose(output);
}

void longest (int a[])
{
FILE *output=fopen("longest.txt", "w");
int i, longest=a[0];
for (i=0;i<3;i++){
if ( a[i]>longest)
longest = a[i];
}
fprintf(output, "%s%d", "\nLongest side is ", longest);
fclose(output);
}

>How to post? What code tags??

These.

[EDIT]Like this:
[code]/* your code here */[/code]

I'm sure you can google for the method on finding area in a triangle... just write in code the formula.

Originally posted by w00tsoft
I'm sure you can google for the method on finding area in a triangle... just write in code the formula.

I really dun know. I know 1/2 x base x height but what about this?

Can someone please help?

Also, aint the program too long. I know shorter program do exist. How to shorten this program?

You should put the same effort into your programming as in asking questions...You'd be finished by now...

return((baseline*height)/2);

Anyway, my friends managed to get the program BUT still got one problems - area always becomes zero. How to overcome it?


#include <stdio.h>
#include <math.h>

int main(void)
{
void values(int []);

FILE *sides;
int i, length[3];
sides = fopen("sides.txt", "r");
if (sides == NULL)
{
printf("Error!\n");
return 0;
}

for (i=0; i<3; i++)
fscanf(sides, "%d", &length[i]);

values(length);

fclose(sides);
return 0;
}

void values(int length [])
{
FILE *output=fopen("output.txt","w");
int i, shortest=length[0], longest=length[0], perimeter=0;
double area, s;

fprintf(output, "Values of triangle:\n");
//Calculate shortest & longest sides
for (i=0;i<3;i++)
{
if ( length[i]<shortest)
shortest = length[i];
if ( length[i]>longest)
longest = length[i];
}
fprintf(output, "%s%d", "\nShortest side is ", shortest);
fprintf(output, "%s%d", "\nLongest side is ", longest);


//Perimeter
for (i=0; i<3; i++)
perimeter += length[i];

fprintf(output, "\nPerimeter is %d\n", perimeter);



//Area
s = perimeter/2.0;
area = s*(s-length[0])*(s-length[1])*(s-length[2]);
area = pow(area, 0.5);

fprintf(output, "%s%.2lf", "\nArea is ", area);

fclose(output);

}

Your area calculation is wrong.

using 10, 4, 6 as side lengths, perimeter is 20.

s = perimeter/2.0; make s= 10
area = s * (s-length[0]) * (s-length[1]) * (s-length[2]);
which makes (s-length[0]) = 0.

Also, you can make each of your fprintf() statements easier byt not outputting a constant string. Change them to

fprintf(output, "Area is %.2f \n", area);

And you didn't use code tags -- click on the link Dave_Sinkula gave you to answer how to use them.

Originally posted by WaltP
Your area calculation is wrong.

using 10, 4, 6 as side lengths, perimeter is 20.

s = perimeter/2.0; make s= 10
area = s * (s-length[0]) * (s-length[1]) * (s-length[2]);
which makes (s-length[0]) = 0.

Also, you can make each of your fprintf() statements easier byt not outputting a constant string. Change them to

fprintf(output, "Area is %.2f \n", area);

And you didn't use code tags -- click on the link Dave_Sinkula gave you to answer how to use them.

Then how should I calculate area? I can't think of any formula. Please help.

No. Your area calculation is correct.
If the 3 lengths are 10, 6 and 4 then the area is 0.
Thats perfectly correct.
Just try to draw that triangle and you will see why.

Correct me if I'm wrong, but it would seem that the 3 sides of 4, 6, 10 seems highly unlikely? I can't draw a triangle with those measurements.

Pythagoras ain't gonna be happy if he sees his formula not working today....

oh and by the way, code tags are basically using "

Code:

" and "

" tags at the start and end of your codes respectively to denote the indents and start/end of your program. hope it helps...

sorry.....i messed it up.

(code) and (/code) but using square brackets instead.

apologies for a confusing reply...