should this work

[amanayin]

The program is simple and i know i should use switch instead of if
but i done it this way for a reason. But i am not sure if it should work
when i was compiling it i was getting warning messages but then suddenly
it started working. The reason i wrote the program was to get used to using
functions, if statement and logical operators.

/* ARITH1.C SIMPLE CALCULATOR PROGRAM */

#include<stdio.h>

float add(float a, float b);
float sub(float a, float b);
float multi(float a, float b);
float div(float a, float b);
float per(float a, float b);
char call(float math);
float a,b,c,math;
char d;

int main(void)
{
printf("Enter 1st value: ");
scanf("%f",&a);
printf("Enter 2nd value: ");
scanf("%f",&b);

call(d);
return 0;
}
char call(float math)
{

while(d != 'q'){
printf("Enter operand or q to exit: ");
scanf("%s",&d);

if(d == '+')
{ math = add(a,b); }
if(d == '-')
{ math = sub(a,b); }
if(d == '*')
{ math = multi(a,b); }
if(d == '/')
{ math = div(a,b); }
if(d == '%')
{ math = per(a,b); }
if(d != '+' && d != '-' && d != '*' && d != '/' && d != '%' && d != 'q')
{ printf("Operand not accepted try again\n"); continue; }
if(d == 'q')
{ puts("Exiting"); break; }
printf("Total is %.3f\n",math);
}
return math;
}

float add(float a, float b)
{
c = a + b;
return c;
}

float sub(float a,float b)
{
c = a - b;
return c;
}

float multi(float a, float b)
{
c = a * b;
return c;
}

float div(float a, float b)
{
c = a / b;
return c;
}

float per(float a, float b)
{
c = a * b / 100;
return c;
}

[osmium]

amanayin writes:

The program is simple and i know i should use switch instead of if
but i done it this way for a reason. But i am not sure if it should work
when i was compiling it i was getting warning messages but then suddenly
it started working. The reason i wrote the program was to get used to using functions, if statement and logical operators.

/* ARITH1.C SIMPLE CALCULATOR PROGRAM */

#include<stdio.h>

float add(float a, float b);
float sub(float a, float b);
float multi(float a, float b);
float div(float a, float b);
float per(float a, float b);
char call(float math);
float a,b,c,math;
char d;

int main(void)
{
printf("Enter 1st value: ");
scanf("%f",&a);
printf("Enter 2nd value: ");
scanf("%f",&b);

call(d);
I wouldn't do that. You are passing call() a char when it wants a float.
There is not reson to do that in code such as this. It may have no bearing
on the problem you say you *used to have*.

return 0;
}
char call(float math)
{

while(d != printf("Enter operand or q to exit: ");
scanf("%s",&d);

if(d == '+')
{ math = add(a,b); }
if(d == '-')
{ math = sub(a,b); }
if(d == '*')
{ math = multi(a,b); }
if(d == '/')
{ math = div(a,b); }
if(d == '%')
{ math = per(a,b); }
if(d != '+' && d != '-' && d != '*' && d != '/' && d != '%' && d != 'q') { printf("Operand not accepted try again\n"); continue; }
if(d == 'q')
{ puts("Exiting"); break; }
printf("Total is %.3f\n",math);
}
return math;
}

float add(float a, float b)
{
c = a + b;
return c;
}

float sub(float a,float b)
{
c = a - b;
return c;
}

float multi(float a, float b)
{
c = a * b;
return c;
}

float div(float a, float b)
{
c = a / b;
return c;
}

float per(float a, float b)
{
c = a * b / 100;
return c;
}

[Irrwahn Grausewitz]

amanayin <ng******@netscape.net> wrote:

The program is simple and i know i should use switch instead of if
but i done it this way for a reason. But i am not sure if it should work
when i was compiling it i was getting warning messages but then suddenly
it started working. The reason i wrote the program was to get used to using
functions, if statement and logical operators.

/* ARITH1.C SIMPLE CALCULATOR PROGRAM */

#include<stdio.h>

float add(float a, float b);
float sub(float a, float b);
float multi(float a, float b);
float div(float a, float b);
'div' is a bad name for a function, because there's a function with the
same name declared in stdlib.h. Not a problem yet, but if you have to
include stdlib.h later the two definitions will clash. Call it 'divide'
or the like.
float per(float a, float b);
char call(float math);
float a,b,c,math;
char d;

int main(void)
{
printf("Enter 1st value: ");
scanf("%f",&a);
printf("Enter 2nd value: ");
scanf("%f",&b);

call(d);
You pass a character to a funtion that expects a double.
return 0;
}
char call(float math)
1. Why do you pass an argument at all?
2. Your function is declared to return a character.
Later on you return a double.
{

while(d != 'q'){
printf("Enter operand or q to exit: ");
scanf("%s",&d);
The "%s" conversion specifier is for reading strings. It will store any
user input plus a null character at &d, but there's only space for one
character. Use "%c" (overkill) or just d = getchar(); (recommended).

if(d == '+')
{ math = add(a,b); }
if(d == '-')
{ math = sub(a,b); }
if(d == '*')
{ math = multi(a,b); }
if(d == '/')
{ math = div(a,b); }
if(d == '%')
{ math = per(a,b); }
if(d != '+' && d != '-' && d != '*' && d != '/' && d != '%' && d != 'q')
{ printf("Operand not accepted try again\n"); continue; }
if(d == 'q')
{ puts("Exiting"); break; }
printf("Total is %.3f\n",math);
}
return math;
See above.
}

float add(float a, float b)
{
c = a + b;
return c;
}

float sub(float a,float b)
{
c = a - b;
return c;
}

float multi(float a, float b)
{
c = a * b;
return c;
}

float div(float a, float b)
See above.
{
c = a / b;
return c;
}

float per(float a, float b)
{
c = a * b / 100;
return c;
}

Besides of the mentioned problems your code looks fine AFAICT.

HTH

Regards
--
Irrwahn
(ir*******@freenet.de)

[Mark Gordon]

On Sun, 19 Oct 2003 16:41:20 +0000 (UTC)
amanayin <ng******@netscape.net> wrote:

The program is simple and i know i should use switch instead of if
but i done it this way for a reason. But i am not sure if it should
work when i was compiling it i was getting warning messages but then
suddenly it started working. The reason i wrote the program was to get
used to using functions, if statement and logical operators.

/* ARITH1.C SIMPLE CALCULATOR PROGRAM */

#include<stdio.h>

float add(float a, float b);
float sub(float a, float b);
float multi(float a, float b);
float div(float a, float b);
float per(float a, float b);
char call(float math);
float a,b,c,math;
char d;
Why declare these as globals? It is far easier to get things right if
you minimise the scope of variables.
int main(void)
{
printf("Enter 1st value: ");
scanf("%f",&a);
printf("Enter 2nd value: ");
scanf("%f",&b);

call(d);
call is declared as taking a float but you are passing a character. You
compiler should have warned you about this. Also d has not been
initialised and by passing it as a parameter you are evaluating it.
return 0;
}
char call(float math)
You never use the value passed in so why have it as a parameter?
{

while(d != 'q'){
d still has not been initialised so absolutely ANYTHING could happen
here.
printf("Enter operand or q to exit: ");
This may not actually be printed before the scanf. Read the FAQ for
further information.
scanf("%s",&d);
%s fetches a null terminated string, not a single character but you are
only passing the address of a single character, so this is guaranteed to
overflow on any input.
if(d == '+')
{ math = add(a,b); }
if(d == '-')
{ math = sub(a,b); }
if(d == '*')
{ math = multi(a,b); }
if(d == '/')
{ math = div(a,b); }
if(d == '%')
{ math = per(a,b); }
if(d != '+' && d != '-' && d != '*' && d != '/' && d != '%' && d
!= 'q')
{ printf("Operand not accepted try again\n"); continue; }
if(d == 'q')
{ puts("Exiting"); break; }
The break will exit the while loop making the condition completely
pointless once all the other bugs are fixed.
printf("Total is %.3f\n",math);
}
return math;
}

float add(float a, float b)
{
c = a + b;
return c;
Why are you using a global variable here? Why not just use
return a + b;
}

<snip>

I seriously think you need to do work through a decent text book. You
will find recommendations in the FAQ for comp.lang.c (Q 18.10)
--
Mark Gordon
Paid to be a Geek & a Senior Software Developer
Although my email address says spamtrap, it is real and I read it.

[Irrwahn Grausewitz]

Irrwahn Grausewitz <ir*******@freenet.de> wrote:

s/double/float/

--
Irrwahn
(ir*******@freenet.de)

[Irrwahn Grausewitz]

Mark Gordon <sp******@flash-gordon.me.uk> wrote:

amanayin <ng******@netscape.net> wrote:

<snip>

{
while(d != 'q'){

d still has not been initialised so absolutely ANYTHING could happen
here.

d has been initialized to 0 automatically on declaration.

Regards
--
Irrwahn
(ir*******@freenet.de)

[Mark Gordon]

On Sun, 19 Oct 2003 21:06:05 +0200
Irrwahn Grausewitz <ir*******@freenet.de> wrote:

Mark Gordon <sp******@flash-gordon.me.uk> wrote:

amanayin <ng******@netscape.net> wrote:

<snip>

{
while(d != 'q'){

d still has not been initialised so absolutely ANYTHING could happen
here.

d has been initialized to 0 automatically on declaration.

You're right. I saw so many problems in how the code was written I saw
more problems than were there.
--
Mark Gordon
Paid to be a Geek & a Senior Software Developer
Although my email address says spamtrap, it is real and I read it.

[pete]

Irrwahn Grausewitz wrote:

'div' is a bad name for a function,
because there's a function with the same name declared in stdlib.h.
Not a problem yet,

I think it is a problem.

My copy of the C89 last draft, has this:
4.1.2 Standard headers
All external identifiers declared in any of the headers are
reserved, whether or not the associated header is included.

--
pete

[Barry Schwarz]

On Sun, 19 Oct 2003 19:34:50 +0100, Mark Gordon
<sp******@flash-gordon.me.uk> wrote:

On Sun, 19 Oct 2003 16:41:20 +0000 (UTC)
amanayin <ng******@netscape.net> wrote:

The program is simple and i know i should use switch instead of if
but i done it this way for a reason. But i am not sure if it should
work when i was compiling it i was getting warning messages but then
suddenly it started working. The reason i wrote the program was to get
used to using functions, if statement and logical operators.

/* ARITH1.C SIMPLE CALCULATOR PROGRAM */

#include<stdio.h>

float add(float a, float b);
float sub(float a, float b);
float multi(float a, float b);
float div(float a, float b);
float per(float a, float b);
char call(float math);
float a,b,c,math;
char d;

Why declare these as globals? It is far easier to get things right if
you minimise the scope of variables.

int main(void)
{
printf("Enter 1st value: ");
scanf("%f",&a);
printf("Enter 2nd value: ");
scanf("%f",&b);

call(d);

call is declared as taking a float but you are passing a character. You
compiler should have warned you about this. Also d has not been

Why would you expect a warning when the conversion from char to float
is automatic and well defined?

<<Remove the del for email>>

[Irrwahn Grausewitz]

pete <pf*****@mindspring.com> wrote:

Irrwahn Grausewitz wrote:

'div' is a bad name for a function,
because there's a function with the same name declared in stdlib.h.
Not a problem yet,

I think it is a problem.

You're right. I should have said: "Possibly not causing real trouble
yet, but definitely a problem ..."

Regards
--
Irrwahn
(ir*******@freenet.de)

[amanayin]

Irrwahn Grausewitz wrote:

snip

while(d != 'q'){
printf("Enter operand or q to exit: ");
scanf("%s",&d);

The "%s" conversion specifier is for reading strings. It will store any
user input plus a null character at &d, but there's only space for one
character. Use "%c" (overkill) or just d = getchar(); (recommended).

If i use d = getchar(); or %c instead of %s i get the
following out put
Enter operand or q to quit: operand not accepted try again:
change it back to %s it works fine

[amanayin]

Mark Gordon wrote:

char call(float math)

You never use the value passed in so why have it as a parameter?

so what should i change it to?

[Mark Gordon]

On Mon, 20 Oct 2003 18:27:43 +0000 (UTC)
amanayin <ng******@netscape.net> wrote:

Mark Gordon wrote:

char call(float math)

You never use the value passed in so why have it as a parameter?

so what should i change it to?

When you want a variable within a function you should declare it within
that function.

From memory something like

void call(void)
{
float math;
/* do stuff */
}

would have been better.
--
Mark Gordon
Paid to be a Geek & a Senior Software Developer
Although my email address says spamtrap, it is real and I read it.

[amanayin]

Thanks for that