Thread: My very first own C program (I need a hand!)

Be nice to your user:

Code:

int e,m,bpm,y;
printf("Enter the Beats Per Minute (BPM) :"); //That would be the BPM's

I would also suggest you use data types that support fractions since you are dividing quite a bit.

Yes I wanted to change the sentence once I got it to work.
Other data type to get the decimals, would that be "float" ?

Originally Posted by Memloop

1) You use m before it's defined.
2) Fix the indentation.
3) int main(void)
4) system("pause") is not standard.

I tried reversing them this morning (I didnt post the updated code), but it didn't work.

system("pause") is not standard? I saw a quick tuto using "getchar", is that more standard?
Looks like tutos differ a lot for a simple "Hello Word!"...

Originally Posted by Exutus

damn it won't work
I love it LOL

Gives me 0

Code:

#include <stdio.h>
main()
{
  double e,m,BPM,y;
  m=60;
  y=m/BPM;
  e=y/2;
  printf("Enter your BPM :");
  scanf("%if",&BPM);
  printf("Echo = %if\n",e);
  system("pause");
}

And why is sytem("pause") a security issue ??
Thanks a lot for you help !

Take a moment, and read what your code does. Line by line.

Code:

double e,m,BPM,y;

declare some variables of type double. They values are completely random at this point.

Code:

m=60;

Assign the value of 60 to m. No problems so far.

Code:

y=m/BPM;

Divide m by BPM. What a second... what does BPM equal? You are essentially saying, "divide m by a completely random number, and assign the result to y". This doesn't work.

Change your initial assignment into a float value - 0.0, instead of 0.

It sounds stupid, but compilers are not the smartest knife in the drawer when it comes to handling floats.

Two other points:
1) Comparing a float to a number, like if(x != 0), is not good, because floats can't be perfectly represented for each value - so they'll be close, but not spot on, for many values. That makes your comparison not work as you think it should, and it's frustrating.

Instead, think of a range, like if(x > 1). Those kind of range comparisons, work fine with floats, in general.

2) It's tempting, and I do it myself sometimes, but the habit of including two lines of code on the same line of text, is generally a very bad habit.

The problem with system("pause"), is that not all systems have a "pause" command - and some smart cracker can replace the pause command program with their own viral version of a "pause", command, and jack your whole system into the middle of next week.

Just a simple :

Code:

printf("\n\n\t\t\t     press enter when ready");  //center a short message
int or char variable name = getchar();            //hold the console window open until enter pressed
return 0;

is what I use, commonly.

You initialize m to zero, therefore y will be zero in the divide, and thus your answer will be zero.

Also, your last printf is missing a variable to use to complete the formatting you are asking it to do.

Thanks Adak
Unfortuatly, it still give me 0.000

Code:

#include <stdio.h>
main()
{
double e,m,x,y; e = m = x= y = 0.0;
printf("Enter value for x :");
scanf("%lf",&x);
if(x != 0.0) y = m/x;
e=y/2.0f;
printf("Echo = %.3lf\n");
system("pause");
}

Originally Posted by Exutus

Thanks Adak
Unfortuatly, it still give me 0.000

Code:

#include <stdio.h>
main()
{
double e,m,x,y; e = m = x= y = 0.0;
printf("Enter value for x :");
scanf("%lf",&x);
if(x != 0.0) y = m/x;
e=y/2.0f;
printf("Echo = %.3lf\n");
system("pause");
}

1) You really should write int main(). The use of functions without an explicit return value like this is depreciated. The implicit return value is int anyway.
2)m should be 60, as per original code. You just need to set it to 60 before you use it.
3)all lines withing the brackets of the function should be indented. It makes the code easy to read for those trying to help you.
4)Only use 1 semicolon per line, aside from for loops. Again, its easier to read.
5)The 2.0f should just be 2.0.
6)You don't pass a variable to printf. You need to print e.
7)Use descriptive variable names. Single letter names are rarely descriptive. Again, it makes it easier for us and you to follow your code.
8)You need to put return 0 at the end of main. The 0 is used to indicate to the OS that your program ran successfully.
9)the if and parenthesis should have their own line. Indent the line that follows to indicate that it is part of the if statements. Again, this is a legibility convention.