CODEWITHSUNDEEP
iosobjective-cgenericsmacrosnslog
fyxrhyry
fyxrhyry

Reputation: 135

Format specifies type 'int' but the argument has type 'NSString *'

Anyone:

I want to use one macro to print log, following,

#define isaObject(parameter) _Generic((parameter), id: YES, id __strong: YES, default: NO)
#define kNSLog(parameter) do                   \
    {                                          \
        BOOL is = isaObject((parameter));      \
        if (is)                                \
        {                                      \
            NSLog(@"----Yes : %@", parameter); \
        }                                      \
        else                                   \
        {                                      \
            NSLog(@"----No : %d", parameter);  \
        }                                      \
    } while (NO)


int i = 99;
NSString * s = @"abcd";

kNSLog(i);
kNSLog(s);

Then, the Compiler gave the warning "Format specifies type 'int' but the argument has type 'NSString *'".

How to modify, Please?

Upvotes: 2

Views: 3787

Answers (3)

Anil Sharma
Anil Sharma

Reputation: 16

 #define isaObject(parameter) _Generic((parameter), id: YES, id __strong: YES, default: NO)

  #define kNSLog(parameter) do                  
  {                                          
      BOOL is = isaObject((parameter));      
      if (is)                                
      {                                     
          NSLog(@"----Yes : %@", parameter);
      }                                      
      else                                   
      {                                      
          NSLog(@"----No : %d", parameter);  
      }                                      
  }

   while (NO)

plz use ------>

NSString * s = @"YES";

kNSLog(s);

Upvotes: 0

Gabriele Petronella
Gabriele Petronella

Reputation: 108151

Well that's pretty easy to debug if you perform the macro replacement "by hand".

kNSLog(s)

expands to

do
{                                        
    BOOL is = isaObject((s));
    if (is)                                
    {                                      
        NSLog(@"----Yes : %@", s); 
    }                                      
    else                                   
    {                                      
        NSLog(@"----No : %d", s); // the warning is thrown here
    }                                      
} while (NO)

You are explicitly checking the type of the parameter, but you didn't inform the compiler about this, so it see that one branch may actually be trying to print an NSString using a %d format.

The solution is to explicitly cast the parameter after you check it, so that you provide the compiler with enough information to keep it silent. Specifically

    if (is)                                
    {                                      
        NSLog(@"----Yes : %@", parameter); 
    }                                      
    else                                   
    {                                      
        NSLog(@"----No : %d", (int)parameter);
    }

Upvotes: 2

picciano
picciano

Reputation: 22701

You can explicitly cast the parameter to an int to avoid that warning:

NSLog(@"----No : %d", (int)parameter); \

Upvotes: 6

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