CODEWITHSUNDEEP
ccompiler-errorsprintfc-preprocessor
yoni
yoni

Reputation: 1364

Strange error with #define in c

I know that #define replaced before the compiling to real values. so why the first code here compile with no error, and the 2nd not?

the 1st;

#include <stdio.h>
#include <stdlib.h>
int main()
{
   printf("bc");
   return 0;
}

the 2nd(not working);

#include <stdio.h>
#include <stdlib.h>
#define Str "bc";
int main()
{
   printf(Str);
   return 0;
}

error: expected ')' before ';' token

thank you for the answers, and sorry about my poor English...

Upvotes: 0

Views: 878

Answers (7)

Windows programmer
Windows programmer

Reputation: 8065

The first one doesn't work because these lines:

#define Str "bc";
printf(Str);

expand to this line:

printf("bc";);

You want:

#define Str "bc"

Upvotes: 1

Fedor Skrynnikov
Fedor Skrynnikov

Reputation: 5609

You need to remove ; where you define str. Because you will get printf("bc";);

Upvotes: 2

Petar Ivanov
Petar Ivanov

Reputation: 93010

The problem with the first one is that Str is replaced with "bc";.

Change it to 

#define Str "bc"

Upvotes: 3

Karoly Horvath
Karoly Horvath

Reputation: 96258

Use

#define Str "bc"

with your define after the substitution it will look like:

printf("bc";);

Upvotes: 3

Crashworks
Crashworks

Reputation: 41374

Because the Str macro evaluates to "bc"; — the semicolon is included. So your macro expands to:

printf("bc";);

You do not need to follow a #define with a semicolon. They end at a newline, rather than at the semicolon like a C statement. It is confusing, I know; the C preprocessor is a strange beast and was invented before people knew better.

Upvotes: 4

Jesus Ramos
Jesus Ramos

Reputation: 23268

The first code does not compile because you need to remove the semicolon after the #define the 2nd code works as it should.

Upvotes: 1

cnicutar
cnicutar

Reputation: 182619

Actually the second works and the first doesn't. The problem is the semicolon:

#define Str "bc";
                ^

Upvotes: 4

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