Thread: Misplaced else in function main -- help?

Hello,

i'm a newbie with C
i started learning it like 2 weeks ago by getting a few ebooks that i've found online..

attached with the ebook a booklet full of exercises to test what i've learned for each chapter but without the solutions .. :S

i managed to get through most tests but im stuck at these two.. hope you could point out wht im doing wrong:

Write a complete C program that asks the user to enter continuously a series of words and the
word “end” to stop.
For each word entered, you should output the number of characters of this word and then ask him
to enter the other word.
Finally, when he finished entering all the words, you should output the number of words entered
(excluding “end”)

Code:

#include <stdio.h>
int main(void)
{
char word[256];
char stop[3]="end";
int cnt=0;
printf("Enter a word to know it's number of characters. once finished enter \"end\" to stop\n");
scanf("%s",&word);
while (stop!=word)
printf("The number of characters of %s is %u\n",word,strlen(word));
cnt = cnt++;
else
printf("you've decided to stop. you entered %d words so far.\n",cnt);
return 0;	
}

and this is the error:

Borland C++ 5.5.1 for Win32 Copyright (c) 1993, 2000 Borland
tma.c:
Warning W8065 tma.c 10: Call to function 'strlen' with no prototype in function main
Error E2054 tma.c 11: Misplaced else in function main
*** 1 errors in Compile ***

Write a complete C program that calculates the roots of any quadratic equation of the form ax2 +
bx + c = 0 where a, b and c are variables that should be entered by user.
First, if a = 0 then the root is x= -c/b
otherwise, you have to find Δ, Δ=b2 – 4ac
If Δ< 0 there are no roots
If Δ= 0 we have 2 double roots: x1 = x2 = -b/2a
If Δ>0, two roots x1 = (-b-√Δ)/2a and (–b +√Δ)/2a
Hint: you can include math library to use some math functions

Code:

#include "stdio.h"
#include "math.h"

void main()
{
int a,b,c,delta;
float x,x1;
printf("\n Enter values of a,b,c for finding roots of a quadratic eq:\n");
scanf("%d%d%d",&a,&b,&c);

if (a == 0) {
x = -c/b
printf("in this case the root is %f",x);
}
else
 delta=b^2-4*a*c

if ( delta<0)
{
printf("there are no roots")
}
if (delta == 0)
{
x= -b/(2*a);
printf("we have double roots %f",x);
}
if (delta>0)
{ 
x = (-b-sqrt(delta))/2*a)
x1 = (-b+sqrt(delta)/2*a
printf("we have two roots which are %f and %f",x,x1);
}
}

ERROR:

Borland C++ 5.5.1 for Win32 Copyright (c) 1993, 2000 Borland
new.c:
Error E2379 new.c 13: Statement missing ; in function main
Error E2379 new.c 18: Statement missing ; in function main
Warning W8004 new.c 33: 'x' is assigned a value that is never used in function main
Warning W8004 new.c 33: 'delta' is assigned a value that is never used in function main
*** 2 errors in Compile ***

The else must have a matching if, but there isn't any. In fact, it looks like you don't need an else.

By the way, you should indent your code properly. If you do so, you may discover a logic error due to the lack of braces.

Start by doing so... First, indent your code.
Second, check all your lines of code for missing ; (there are at least two).
Third, check all your lines for missing parenthesises (there is at least one).
And fourth, there is a problem in the algorithm. a^2 is not a squared (it's a XOR 2). Nor should there be any squared variables in the formula. Look at it again, closely.
And last, you are missing parenthesises again. When you have a*b/c*d, you'll have to add parenthesises, remember? This is like a calculator.
And change void main to int main.

Fix your indentation.
It's your tool for finding these kinds of things.

For example, Visual Studio has an indentation tool. There are others.
But it isn't difficult to do it yourself. Consider this indented code of yours. You should be able to spot the problem:

Code:

#include <stdio.h>
#include <math.h>
int main (void)
{
	int a,b,c;
	float x,x1,x2,y,delta;
	printf("enter three numbers please\n");
	scanf("%d%d%d",a,b,c);
	delta=b*b-4*a*c;
	if (a==0)
		x=(-c/b);
	printf("the root is %f\n",x);
	else 
		printf("Delta=b2-4ac is equal to %f\n",delta);

	if (delta<0)
		printf("there are no roots\n");
	else
		if (delta==0)
			y=(-b/(2*a));
	printf("we have double roots x1=x2=%d/2*%d=%f\n",a,b,y);
		else
			if (delta>0)
				x1=((-b+sqrt(delta))/(2*a));
	x2=((-b+sqrt(delta))/(2*a));
	printf("there are two roots which are %f and %f\n",x1,x2);

	return 0;	     	 
}

Originally Posted by Elysia

For example, Visual Studio has an indentation tool. There are others.
But it isn't difficult to do it yourself. Consider this indented code of yours. You should be able to spot the problem:

Code:

#include <stdio.h>
#include <math.h>
int main (void)
{
	int a,b,c;
	float x,x1,x2,y,delta;
	printf("enter three numbers please\n");
	scanf("%d%d%d",a,b,c);
	delta=b*b-4*a*c;
	if (a==0)
		x=(-c/b);
	printf("the root is %f\n",x);
	else 
		printf("Delta=b2-4ac is equal to %f\n",delta);

	if (delta<0)
		printf("there are no roots\n");
	else
		if (delta==0)
			y=(-b/(2*a));
	printf("we have double roots x1=x2=%d/2*%d=%f\n",a,b,y);
		else
			if (delta>0)
				x1=((-b+sqrt(delta))/(2*a));
	x2=((-b+sqrt(delta))/(2*a));
	printf("there are two roots which are %f and %f\n",x1,x2);

	return 0;	     	 
}

im using notepad
and command line Borland C++ 5.5.1 for Win32 Copyright (c) 1993, 2000 Borland

i downloaded "Microsoft Visual C++ 2008 Express Edition"
though i'm ashamed to admit that i didn't know how to use it..

PS: thanks for your effort by indenting but i'm still not noticing the prob..
i'm reading the notes ive taken from the net over and over again..
im pretty sure there's something im missing but im not finding it out..

Code:

#include <stdio.h>
#include <math.h>
int main (void)
{
	int a,b,c;
	float x,x1,x2,y,delta;
	printf("enter three numbers please\n");
	scanf("%d%d%d",a,b,c);
	delta=b*b-4*a*c;
	if (a==0)
		x=(-c/b);
	printf("the root is %f\n",x);
	else 
		printf("Delta=b2-4ac is equal to %f\n",delta);

	if (delta<0)
		printf("there are no roots\n");
	else
		if (delta==0)
			y=(-b/(2*a));
	printf("we have double roots x1=x2=%d/2*%d=%f\n",a,b,y);
		else
			if (delta>0)
				x1=((-b+sqrt(delta))/(2*a));
	x2=((-b+sqrt(delta))/(2*a));
	printf("there are two roots which are %f and %f\n",x1,x2);

	return 0;	     	 
}

Problematic lines are in red.
We see from the indentation that, for example, the printf lines do not belong to the IF statement. Braces are required if you want more than one statement in an if.
As a result of this, the else does not directly follow the if, and therefore, the compiler cannot determine which if statement it belongs to and so it complains.
There are many good tutorials on Visual Studio on the web.
Even if you don't use it, you shouldn't use Notepad for creating code. Either use a real editor or an IDE.

All I can say is that it's not a logic problem that causes your crash.
I could elaborate on where and why, if you want, but seeing as you did state you want to find it yourself, you'll have to make another reply if you want it.
Take your time.

scanf requires pointers to where it should store the input. You are merely passing the contents of the variables to scanf.
Aside from that, you should probably be getting warnings in some form or another.