Simple program closing at end, no time to read...

Hi,

I've started programming in C a few weeks ago and have decided to start writing a calculator for every topic/subject I get in maths at school.

When I was writing my most recent, I came across a problem that it would not give the user time to read the final answer at the end. I must be doing something slightly wrong (and probably very stupidly simple aswell lol!). Does anybody know what's wrong with my source code below?

Code:

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/* A Program by Jake C to work out the gradient of a line by entering
  2 coordinates */
 
#include <stdio.h>
#include <stdlib.h>

main()
{
      char xone[20];
      char xtwo[20];
      float xintone;
      float xinttwo;
      char yone[20];
      char ytwo[20];
      float yintone;
      float yinttwo;
      float answer;
     
     
      printf("Please enter the first set of coordinates seperated by a space:\n");
      scanf("%s",xone);
      scanf("%s",xtwo);
      xintone=atof(xone);
      xinttwo=atof(xtwo);
     
      printf("Please enter the second set of coordiantes seperated by a space:\n");
      scanf("%s",yone);
      scanf("%s",ytwo);
      yintone=atof(yone);
      yinttwo=atof(ytwo);
     
      answer=(yinttwo-yintone)/(xinttwo-xintone);
     
      printf("The gradient of the line is:\n\n%f",answer);
      getchar();
     
      return(0);
}

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Thanks - I'm new to the forum and it seems like a really informative place! I'm looking forward to being here.

Jake

scanf leaves the \n char in the input buffer
getchar(); reads it and continues without pause

add another - or (better IMHO) just run the program from the command prompt

Thanks! that seems to have worked - but now there's another problem, when it prints the "answer" float, it comes up with 1.#INF...

Don't suppose anyone knows why that is?

Could be a couple of things:
1. xinttwo and yintone are not what they should be. (Look at your atof statements again.)
2. Maybe it really is a line of infinite slope (i.e., vertical) -- again, modulo your x/y backwardness above.
3. Double check atof if all fails (print out values of xintone etc.)

You have two other flaws in your program, though.
First is implicit main.
Second is your scanf reading. Check this for proper reading strings.
C is not a kind and safe language which puts that burden on YOU to do it right.

Quote:

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Originally Posted by Elysia

You have two other flaws in your program, though.
First is implicit main.
Second is your scanf reading. Check this for proper reading strings.
C is not a kind and safe language which puts that burden on YOU to do it right.

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So I should have "int main(void)" instead of "main()"?

I've also corrected the buffer overflows.

Quote:

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Originally Posted by tabstop

Could be a couple of things:
1. xinttwo and yintone are not what they should be. (Look at your atof statements again.)
2. Maybe it really is a line of infinite slope (i.e., vertical) -- again, modulo your x/y backwardness above.
3. Double check atof if all fails (print out values of xintone etc.)

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I can't see anything wrong with xinttwo and yintone...

And it does it for all coordinates, not just vertical.

I printed out all of the float variables and they were all fine...

Thanks anyway though.

You read the value y1 into a variable named "xtwo" (and consequently xinttwo) and you read the value x2 into a variable named "yone" (and consequently yintone). If xintone, etc. print fine, then answer should be computed fine.

Quote:

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Originally Posted by Jake.c

So I should have "int main(void)" instead of "main()"?

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Yeah.

Quote:

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I've also corrected the buffer overflows.

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Terrific! You're a great student! ;)

Quote:

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Originally Posted by tabstop

You read the value y1 into a variable named "xtwo" (and consequently xinttwo) and you read the value x2 into a variable named "yone" (and consequently yintone). If xintone, etc. print fine, then answer should be computed fine.

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Ah of course - how did I miss that?!?! I said it would be something simple haha!

Thanks everyone!

Jake