c programming

teval · 12-06-2003, 10:34 AM

Code:

	if(a == 1);printf("%f+%f=%f",b,c,b+c);
	if(a == 2);printf("%f-%f=%f",b,c,b-c);
	if(a == 3);printf("%fx%f=%f",b,c,b*c);
	if(a == 4);printf("%f/%f=%f",b,c,b/c);

That will not have the desired effect.
It will check if a==1 and then regardless of the result run printf.
Don't put the ; after if.

Inuyasha-kun · 12-06-2003, 08:09 PM

Thanks, that fixed the entire problem.

Do you know how to make the program to execute without the "./" ?

Tarts · 12-06-2003, 09:35 PM

Quote:

Originally posted by Inuyasha-kun
Thanks, that fixed the entire problem.

Do you know how to make the program to execute without the "./" ?

If its a user account, you can add the directory where the executable(s) lies to that users path, I have a "home made" executable directory for all the programs I make.

Tarts

Inuyasha-kun · 12-22-2003, 07:25 PM

Since it was Christmas break, I decided to practice with C. i was wondering, why does this code give out so many warnings?

Code:

#include <stdio.h>
//A is the number to pick the operation
//B and C are the single-precision floating point variables that will be modified
int a;
float b,c;
int main()
{
	float e;
	printf("NCalc 1.0b for Linux\nPick an op\n1:Add\n2:Sub\n3:Mul\n4:Div\n:");
	scanf("%d",&a);
	printf("\nNumber 1:");
	scanf("%f",&b);
	printf("\nNumber 2:");
	scanf("%f",&c);
	if(a == 1) printf("%f+%f=%f\n",b,c,addit(e));
	if(a == 2) printf("%f-%f=%f\n",b,c,subit(e));
	if(a == 3) printf("%fx%f=%f\n",b,c,mulit(e));
	if(a == 4) printf("%f/%f=%f\n",b,c,divit(e));
	return 0;
}
void addit(float d)
{
	float d;
	d=b+c;
	return d;
}
void subit(float d)
{
	float d;
	d=b-c;
	return d;
}
void mulit(float d)
{
	float d;
	d=b*c;
	return d;
}
void divit(float d)
{
	float d;
	d=b/c;
	return d;
}

afrm · 12-22-2003, 09:47 PM

Use this command to compile your C programs :

gcc -Wall -ansi -pedantic -g <file_name1>.c <file_name2>.c ... -o <prog_name>

teval · 12-23-2003, 12:04 AM

Quote:

Originally posted by Inuyasha-kun
Since it was Christmas break, I decided to practice with C. i was wondering, why does this code give out so many warnings?

Code:

#include <stdio.h> //A is the number to pick the operation //B and C are the single-precision floating point variables that will be modified int a; float b,c; int main() { float e; printf("NCalc 1.0b for Linux\nPick an op\n1:Add\n2:Sub\n3:Mul\n4:Div\n:"); scanf("%d",&a); printf("\nNumber 1:"); scanf("%f",&b); printf("\nNumber 2:"); scanf("%f",&c); if(a == 1) printf("%f+%f=%f\n",b,c,addit(e)); if(a == 2) printf("%f-%f=%f\n",b,c,subit(e)); if(a == 3) printf("%fx%f=%f\n",b,c,mulit(e)); if(a == 4) printf("%f/%f=%f\n",b,c,divit(e)); return 0; } void addit(float d) { float d; d=b+c; return d; } void subit(float d) { float d; d=b-c; return d; } void mulit(float d) { float d; d=b*c; return d; } void divit(float d) { float d; d=b/c; return d; }

To start, you didn't declare the functions before you used them. Either make a header file, or include the same info at the start of your file. The output from gcc would be nice

but that should solve a lot of your pbelms. Another is that you declare d twice inside your functions

void divit(float d)
{
float d;

What happens is whatver flat divit gets, it names d and continues. This is the same as declaring the same variable twice.

Also a suggestion

try to name your variables well. Things end up getting mangled otherwise. Another thing is that you return something when you declared that function void. Declare it to return a float if you want to do that. That's everything I caught at first glance

The gcc error messages will show whaterver is left.

clockworks · 12-23-2003, 02:19 PM

Quote:

Originally posted by aizkorri
To compile use this

gcc -o execname -c yourprogram.c

If you don't use the -o option it will create a a.out where the executabe is. To execute the program write ./execname.

this will compile yourprogram.c into an object file. i will not link it to the c lib and make it an executable.

what you want to type is:

gcc -o execname yourprogram.c

-- C

clockworks · 12-23-2003, 02:29 PM

Quote:

Originally posted by Inuyasha-kun
Since it was Christmas break, I decided to practice with C. i was wondering, why does this code give out so many warnings?

Code:

#include <stdio.h> //A is the number to pick the operation //B and C are the single-precision floating point variables that will be modified int a; float b,c; int main() { float e; printf("NCalc 1.0b for Linux\nPick an op\n1:Add\n2:Sub\n3:Mul\n4:Div\n:"); scanf("%d",&a); printf("\nNumber 1:"); scanf("%f",&b); printf("\nNumber 2:"); scanf("%f",&c); if(a == 1) printf("%f+%f=%f\n",b,c,addit(e)); if(a == 2) printf("%f-%f=%f\n",b,c,subit(e)); if(a == 3) printf("%fx%f=%f\n",b,c,mulit(e)); if(a == 4) printf("%f/%f=%f\n",b,c,divit(e)); return 0; } void addit(float d) { float d; d=b+c; return d; } void subit(float d) { float d; d=b-c; return d; } void mulit(float d) { float d; d=b*c; return d; } void divit(float d) { float d; d=b/c; return d; }

omg, i don't even know where to begin...

1) you used the functions addit(), subit(), mulit(), divit() before you declared them.
2) in those functions mentioned about, you have "d" declared twice...as a formal parameter and as a local variable.
3) you claim those functions to return void, but you are really returning a float (i.e. you are returning d).

i think those three things are what are causing your warnings...now on what else is wrong.

1) "a", "b", and "c" are global, this is not good programming practice.
2) you functions don't make much sense. you should do away with the vars "b", "c", and "d" and define your functions like this:

Code:

float addit(float a, float b)	{
	return a + b;
}

what you >really< need to do is take a class from a >good< teacher, or get a >good< book on c and another good book on good/proper programming practices...

-- C

teval · 12-23-2003, 09:16 PM

I think the best teacher is good code. Go on sourceforge, get a good book (I don't know any good C books, only C++ books), read, and look at the code. Then implement something similar, without looking at the code this time.
You'll learn a lot.