CODEWITHSUNDEEP
c
Tom
Tom

Reputation: 9643

c - warning: implicit declaration of function ‘printf’

I know alot of similar questions were asked before but i couldn't find something that would fix this warning i get:

MyIntFunctions.c:19:2: warning: implicit declaration of function ‘printf’ [-Wimplicit-function-declaration]

Occurs here:

void IntPrint (const void *key)
{
    printf("%d", *(int*)key); // line 19
    printf("\t-->\t");
}

and a similar warning:

MyStringFunctions.c:22:2: warning: implicit declaration of function ‘printf’ [-Wimplicit-function-declaration]

void StringPrint (const void *key)
{
    printf("%s",(char*)key); //line 22
    printf("\t-->\t");
}

I really want to understand what is wrong so i won't do that again in the future.

Upvotes: 70

Views: 186210

Answers (4)

Amogh24
Amogh24

Reputation: 1

warning: incompatible implicit declaration of built-in function 'printf'

warning: incompatible implicit declaration of built-in function 'scanf'

the above warnings of compiler says that there is need to include declaration of printf and scanf i.e. include appropriate header

#include <stdio.h>

Upvotes: -1

oleg_g
oleg_g

Reputation: 532

You need to include a declaration of the printf() function.

#include <stdio.h>

Upvotes: 17

Raghu Srikanth Reddy
Raghu Srikanth Reddy

Reputation: 2711

the warning or error of kind IMPLICIT DECLARATION is that the compiler is expecting a Function Declaration/Prototype..

It might either be a header file or your own function Declaration..

Upvotes: 3

simonc
simonc

Reputation: 42165

You need to include the appropriate header

#include <stdio.h>

If you're not sure which header a standard function is defined in, the function's man page will state this.

Upvotes: 113

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