Question about if-statement.

**omnificient** · 12-21-2007

I was wondering why the following program doesn't function properly:

Code:

#include <stdio.h>

int main()
{
 int a;
 printf("Enter a number: ");
 scanf("%d", a);
 if (a = 1)
    {
     printf("One.\n");
    }
 else
     {
      printf("Not one.\n");
     }
  getchar();
  getchar();
}

It will output: One. No matter what number you input.

The crappy C-tutorial on this site is no good either, since the example of how to use it is written in C++.

Thank You.

**laserlight** · 12-21-2007

Look hard:

Code:

if (a = 1)

See it now?

**Salem** · 12-21-2007

==, not =

The scanf call is wrong as well, it's missing an &

With extra warnings, all those problems are at least hinted at.

Code:

$ gcc -W -Wall -ansi -pedantic -O2 foo.c
foo.c: In function `main':
foo.c:7: warning: format argument is not a pointer (arg 2)
// That's the missing &
foo.c:8: warning: suggest parentheses around assignment used as truth value
// That hints that = should be ==
foo.c:18: warning: control reaches end of non-void function
// you forgot the return 0;
foo.c:5: warning: 'a' might be used uninitialized in this function

**omnificient** · 12-21-2007

Ah well I guess I just need some sleep then. Thanks!

**ssharish2005** · 12-21-2007

Using scanf fucntion to read an integer is a standard procedure which everyone uses, but you can see the impact of using scanf by calling getchar function twice at the end.

There are many better way of reading an integer rather than using scanf function, perhaps using fgets and sscanf function. Have a look

ssharish

**Elysia** · 12-21-2007

Originally Posted by omnificient

Code:

#include <stdio.h>

int main()
{
	int a;
	printf("Enter a number: ");
	scanf("%d", a);
	if (a = 1)
	{
		printf("One.\n");
	}
	else
	{
		printf("Not one.\n");
	}
	getchar();
	getchar();
}

Indentation lesson. There you go.

**ssharish2005** · 12-21-2007

Elysia, one more lesson on indentation lol, why don't you place that indentation note on your signature. That makes your life more easy isn't it?

ssharish

**Elysia** · 12-21-2007

Not enough space >_<
Need to write an essay on indenting and link to it. Maybe once there's a wiki up.

**t3chn0n3rd** · 12-21-2007

Did that program compile

**ssharish2005** · 12-21-2007

Originally Posted by t3chn0n3rd

Did that program compile

That program will compile if you do the necessary changes which is been pointed out.

ssharish

**jas_atwal** · 12-21-2007

and scanf will accept a pointer. so replace scanf("%d", a) with scanf("%d",&a);

**ssharish2005** · 12-21-2007

Originally Posted by jas_atwal

and scanf will accept a pointer. so replace scanf("%d", a) with scanf("%d",&a);

YES thats right, Salem had pointed that one out earlier.

ssharish

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